Source file src/crypto/x509/x509.go

Documentation: crypto/x509

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package x509 implements a subset of the X.509 standard.
     6  //
     7  // It allows parsing and generating certificates, certificate signing
     8  // requests, certificate revocation lists, and encoded public and private keys.
     9  // It provides a certificate verifier, complete with a chain builder.
    10  //
    11  // The package targets the X.509 technical profile defined by the IETF (RFC
    12  // 2459/3280/5280), and as further restricted by the CA/Browser Forum Baseline
    13  // Requirements. There is minimal support for features outside of these
    14  // profiles, as the primary goal of the package is to provide compatibility
    15  // with the publicly trusted TLS certificate ecosystem and its policies and
    16  // constraints.
    17  //
    18  // On macOS and Windows, certificate verification is handled by system APIs, but
    19  // the package aims to apply consistent validation rules across operating
    20  // systems.
    21  package x509
    22  
    23  import (
    24  	"bytes"
    25  	"crypto"
    26  	"crypto/ecdh"
    27  	"crypto/ecdsa"
    28  	"crypto/ed25519"
    29  	"crypto/elliptic"
    30  	"crypto/rsa"
    31  	"crypto/sha1"
    32  	"crypto/x509/pkix"
    33  	"encoding/asn1"
    34  	"encoding/pem"
    35  	"errors"
    36  	"fmt"
    37  	"internal/godebug"
    38  	"io"
    39  	"math/big"
    40  	"net"
    41  	"net/url"
    42  	"strconv"
    43  	"time"
    44  	"unicode"
    45  
    46  	// Explicitly import these for their crypto.RegisterHash init side-effects.
    47  	// Keep these as blank imports, even if they're imported above.
    48  	_ "crypto/sha1"
    49  	_ "crypto/sha256"
    50  	_ "crypto/sha512"
    51  
    52  	"golang.org/x/crypto/cryptobyte"
    53  	cryptobyte_asn1 "golang.org/x/crypto/cryptobyte/asn1"
    54  )
    55  
    56  // pkixPublicKey reflects a PKIX public key structure. See SubjectPublicKeyInfo
    57  // in RFC 3280.
    58  type pkixPublicKey struct {
    59  	Algo      pkix.AlgorithmIdentifier
    60  	BitString asn1.BitString
    61  }
    62  
    63  // ParsePKIXPublicKey parses a public key in PKIX, ASN.1 DER form. The encoded
    64  // public key is a SubjectPublicKeyInfo structure (see RFC 5280, Section 4.1).
    65  //
    66  // It returns a *[rsa.PublicKey], *[dsa.PublicKey], *[ecdsa.PublicKey],
    67  // [ed25519.PublicKey] (not a pointer), or *[ecdh.PublicKey] (for X25519).
    68  // More types might be supported in the future.
    69  //
    70  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
    71  func ParsePKIXPublicKey(derBytes []byte) (pub any, err error) {
    72  	var pki publicKeyInfo
    73  	if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {
    74  		if _, err := asn1.Unmarshal(derBytes, &pkcs1PublicKey{}); err == nil {
    75  			return nil, errors.New("x509: failed to parse public key (use ParsePKCS1PublicKey instead for this key format)")
    76  		}
    77  		return nil, err
    78  	} else if len(rest) != 0 {
    79  		return nil, errors.New("x509: trailing data after ASN.1 of public-key")
    80  	}
    81  	return parsePublicKey(&pki)
    82  }
    83  
    84  func marshalPublicKey(pub any) (publicKeyBytes []byte, publicKeyAlgorithm pkix.AlgorithmIdentifier, err error) {
    85  	switch pub := pub.(type) {
    86  	case *rsa.PublicKey:
    87  		publicKeyBytes, err = asn1.Marshal(pkcs1PublicKey{
    88  			N: pub.N,
    89  			E: pub.E,
    90  		})
    91  		if err != nil {
    92  			return nil, pkix.AlgorithmIdentifier{}, err
    93  		}
    94  		publicKeyAlgorithm.Algorithm = oidPublicKeyRSA
    95  		// This is a NULL parameters value which is required by
    96  		// RFC 3279, Section 2.3.1.
    97  		publicKeyAlgorithm.Parameters = asn1.NullRawValue
    98  	case *ecdsa.PublicKey:
    99  		oid, ok := oidFromNamedCurve(pub.Curve)
   100  		if !ok {
   101  			return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
   102  		}
   103  		if !pub.Curve.IsOnCurve(pub.X, pub.Y) {
   104  			return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: invalid elliptic curve public key")
   105  		}
   106  		publicKeyBytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)
   107  		publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
   108  		var paramBytes []byte
   109  		paramBytes, err = asn1.Marshal(oid)
   110  		if err != nil {
   111  			return
   112  		}
   113  		publicKeyAlgorithm.Parameters.FullBytes = paramBytes
   114  	case ed25519.PublicKey:
   115  		publicKeyBytes = pub
   116  		publicKeyAlgorithm.Algorithm = oidPublicKeyEd25519
   117  	case *ecdh.PublicKey:
   118  		publicKeyBytes = pub.Bytes()
   119  		if pub.Curve() == ecdh.X25519() {
   120  			publicKeyAlgorithm.Algorithm = oidPublicKeyX25519
   121  		} else {
   122  			oid, ok := oidFromECDHCurve(pub.Curve())
   123  			if !ok {
   124  				return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
   125  			}
   126  			publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
   127  			var paramBytes []byte
   128  			paramBytes, err = asn1.Marshal(oid)
   129  			if err != nil {
   130  				return
   131  			}
   132  			publicKeyAlgorithm.Parameters.FullBytes = paramBytes
   133  		}
   134  	default:
   135  		return nil, pkix.AlgorithmIdentifier{}, fmt.Errorf("x509: unsupported public key type: %T", pub)
   136  	}
   137  
   138  	return publicKeyBytes, publicKeyAlgorithm, nil
   139  }
   140  
   141  // MarshalPKIXPublicKey converts a public key to PKIX, ASN.1 DER form.
   142  // The encoded public key is a SubjectPublicKeyInfo structure
   143  // (see RFC 5280, Section 4.1).
   144  //
   145  // The following key types are currently supported: *[rsa.PublicKey],
   146  // *[ecdsa.PublicKey], [ed25519.PublicKey] (not a pointer), and *[ecdh.PublicKey].
   147  // Unsupported key types result in an error.
   148  //
   149  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
   150  func MarshalPKIXPublicKey(pub any) ([]byte, error) {
   151  	var publicKeyBytes []byte
   152  	var publicKeyAlgorithm pkix.AlgorithmIdentifier
   153  	var err error
   154  
   155  	if publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(pub); err != nil {
   156  		return nil, err
   157  	}
   158  
   159  	pkix := pkixPublicKey{
   160  		Algo: publicKeyAlgorithm,
   161  		BitString: asn1.BitString{
   162  			Bytes:     publicKeyBytes,
   163  			BitLength: 8 * len(publicKeyBytes),
   164  		},
   165  	}
   166  
   167  	ret, _ := asn1.Marshal(pkix)
   168  	return ret, nil
   169  }
   170  
   171  // These structures reflect the ASN.1 structure of X.509 certificates.:
   172  
   173  type certificate struct {
   174  	TBSCertificate     tbsCertificate
   175  	SignatureAlgorithm pkix.AlgorithmIdentifier
   176  	SignatureValue     asn1.BitString
   177  }
   178  
   179  type tbsCertificate struct {
   180  	Raw                asn1.RawContent
   181  	Version            int `asn1:"optional,explicit,default:0,tag:0"`
   182  	SerialNumber       *big.Int
   183  	SignatureAlgorithm pkix.AlgorithmIdentifier
   184  	Issuer             asn1.RawValue
   185  	Validity           validity
   186  	Subject            asn1.RawValue
   187  	PublicKey          publicKeyInfo
   188  	UniqueId           asn1.BitString   `asn1:"optional,tag:1"`
   189  	SubjectUniqueId    asn1.BitString   `asn1:"optional,tag:2"`
   190  	Extensions         []pkix.Extension `asn1:"omitempty,optional,explicit,tag:3"`
   191  }
   192  
   193  type dsaAlgorithmParameters struct {
   194  	P, Q, G *big.Int
   195  }
   196  
   197  type validity struct {
   198  	NotBefore, NotAfter time.Time
   199  }
   200  
   201  type publicKeyInfo struct {
   202  	Raw       asn1.RawContent
   203  	Algorithm pkix.AlgorithmIdentifier
   204  	PublicKey asn1.BitString
   205  }
   206  
   207  // RFC 5280,  4.2.1.1
   208  type authKeyId struct {
   209  	Id []byte `asn1:"optional,tag:0"`
   210  }
   211  
   212  type SignatureAlgorithm int
   213  
   214  const (
   215  	UnknownSignatureAlgorithm SignatureAlgorithm = iota
   216  
   217  	MD2WithRSA  // Unsupported.
   218  	MD5WithRSA  // Only supported for signing, not verification.
   219  	SHA1WithRSA // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
   220  	SHA256WithRSA
   221  	SHA384WithRSA
   222  	SHA512WithRSA
   223  	DSAWithSHA1   // Unsupported.
   224  	DSAWithSHA256 // Unsupported.
   225  	ECDSAWithSHA1 // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
   226  	ECDSAWithSHA256
   227  	ECDSAWithSHA384
   228  	ECDSAWithSHA512
   229  	SHA256WithRSAPSS
   230  	SHA384WithRSAPSS
   231  	SHA512WithRSAPSS
   232  	PureEd25519
   233  )
   234  
   235  func (algo SignatureAlgorithm) isRSAPSS() bool {
   236  	switch algo {
   237  	case SHA256WithRSAPSS, SHA384WithRSAPSS, SHA512WithRSAPSS:
   238  		return true
   239  	default:
   240  		return false
   241  	}
   242  }
   243  
   244  func (algo SignatureAlgorithm) String() string {
   245  	for _, details := range signatureAlgorithmDetails {
   246  		if details.algo == algo {
   247  			return details.name
   248  		}
   249  	}
   250  	return strconv.Itoa(int(algo))
   251  }
   252  
   253  type PublicKeyAlgorithm int
   254  
   255  const (
   256  	UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
   257  	RSA
   258  	DSA // Only supported for parsing.
   259  	ECDSA
   260  	Ed25519
   261  )
   262  
   263  var publicKeyAlgoName = [...]string{
   264  	RSA:     "RSA",
   265  	DSA:     "DSA",
   266  	ECDSA:   "ECDSA",
   267  	Ed25519: "Ed25519",
   268  }
   269  
   270  func (algo PublicKeyAlgorithm) String() string {
   271  	if 0 < algo && int(algo) < len(publicKeyAlgoName) {
   272  		return publicKeyAlgoName[algo]
   273  	}
   274  	return strconv.Itoa(int(algo))
   275  }
   276  
   277  // OIDs for signature algorithms
   278  //
   279  //	pkcs-1 OBJECT IDENTIFIER ::= {
   280  //		iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }
   281  //
   282  // RFC 3279 2.2.1 RSA Signature Algorithms
   283  //
   284  //	md2WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 2 }
   285  //
   286  //	md5WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 4 }
   287  //
   288  //	sha-1WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 5 }
   289  //
   290  //	dsaWithSha1 OBJECT IDENTIFIER ::= {
   291  //		iso(1) member-body(2) us(840) x9-57(10040) x9cm(4) 3 }
   292  //
   293  // RFC 3279 2.2.3 ECDSA Signature Algorithm
   294  //
   295  //	ecdsa-with-SHA1 OBJECT IDENTIFIER ::= {
   296  //		iso(1) member-body(2) us(840) ansi-x962(10045)
   297  //		signatures(4) ecdsa-with-SHA1(1)}
   298  //
   299  // RFC 4055 5 PKCS #1 Version 1.5
   300  //
   301  //	sha256WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 11 }
   302  //
   303  //	sha384WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 12 }
   304  //
   305  //	sha512WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 13 }
   306  //
   307  // RFC 5758 3.1 DSA Signature Algorithms
   308  //
   309  //	dsaWithSha256 OBJECT IDENTIFIER ::= {
   310  //		joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101)
   311  //		csor(3) algorithms(4) id-dsa-with-sha2(3) 2}
   312  //
   313  // RFC 5758 3.2 ECDSA Signature Algorithm
   314  //
   315  //	ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   316  //		us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 }
   317  //
   318  //	ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   319  //		us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 }
   320  //
   321  //	ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   322  //		us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 }
   323  //
   324  // RFC 8410 3 Curve25519 and Curve448 Algorithm Identifiers
   325  //
   326  //	id-Ed25519   OBJECT IDENTIFIER ::= { 1 3 101 112 }
   327  var (
   328  	oidSignatureMD2WithRSA      = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 2}
   329  	oidSignatureMD5WithRSA      = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 4}
   330  	oidSignatureSHA1WithRSA     = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 5}
   331  	oidSignatureSHA256WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 11}
   332  	oidSignatureSHA384WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 12}
   333  	oidSignatureSHA512WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 13}
   334  	oidSignatureRSAPSS          = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 10}
   335  	oidSignatureDSAWithSHA1     = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 3}
   336  	oidSignatureDSAWithSHA256   = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 3, 2}
   337  	oidSignatureECDSAWithSHA1   = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 1}
   338  	oidSignatureECDSAWithSHA256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 2}
   339  	oidSignatureECDSAWithSHA384 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 3}
   340  	oidSignatureECDSAWithSHA512 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 4}
   341  	oidSignatureEd25519         = asn1.ObjectIdentifier{1, 3, 101, 112}
   342  
   343  	oidSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 1}
   344  	oidSHA384 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 2}
   345  	oidSHA512 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 3}
   346  
   347  	oidMGF1 = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 8}
   348  
   349  	// oidISOSignatureSHA1WithRSA means the same as oidSignatureSHA1WithRSA
   350  	// but it's specified by ISO. Microsoft's makecert.exe has been known
   351  	// to produce certificates with this OID.
   352  	oidISOSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 29}
   353  )
   354  
   355  var signatureAlgorithmDetails = []struct {
   356  	algo       SignatureAlgorithm
   357  	name       string
   358  	oid        asn1.ObjectIdentifier
   359  	pubKeyAlgo PublicKeyAlgorithm
   360  	hash       crypto.Hash
   361  }{
   362  	{MD2WithRSA, "MD2-RSA", oidSignatureMD2WithRSA, RSA, crypto.Hash(0) /* no value for MD2 */},
   363  	{MD5WithRSA, "MD5-RSA", oidSignatureMD5WithRSA, RSA, crypto.MD5},
   364  	{SHA1WithRSA, "SHA1-RSA", oidSignatureSHA1WithRSA, RSA, crypto.SHA1},
   365  	{SHA1WithRSA, "SHA1-RSA", oidISOSignatureSHA1WithRSA, RSA, crypto.SHA1},
   366  	{SHA256WithRSA, "SHA256-RSA", oidSignatureSHA256WithRSA, RSA, crypto.SHA256},
   367  	{SHA384WithRSA, "SHA384-RSA", oidSignatureSHA384WithRSA, RSA, crypto.SHA384},
   368  	{SHA512WithRSA, "SHA512-RSA", oidSignatureSHA512WithRSA, RSA, crypto.SHA512},
   369  	{SHA256WithRSAPSS, "SHA256-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA256},
   370  	{SHA384WithRSAPSS, "SHA384-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA384},
   371  	{SHA512WithRSAPSS, "SHA512-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA512},
   372  	{DSAWithSHA1, "DSA-SHA1", oidSignatureDSAWithSHA1, DSA, crypto.SHA1},
   373  	{DSAWithSHA256, "DSA-SHA256", oidSignatureDSAWithSHA256, DSA, crypto.SHA256},
   374  	{ECDSAWithSHA1, "ECDSA-SHA1", oidSignatureECDSAWithSHA1, ECDSA, crypto.SHA1},
   375  	{ECDSAWithSHA256, "ECDSA-SHA256", oidSignatureECDSAWithSHA256, ECDSA, crypto.SHA256},
   376  	{ECDSAWithSHA384, "ECDSA-SHA384", oidSignatureECDSAWithSHA384, ECDSA, crypto.SHA384},
   377  	{ECDSAWithSHA512, "ECDSA-SHA512", oidSignatureECDSAWithSHA512, ECDSA, crypto.SHA512},
   378  	{PureEd25519, "Ed25519", oidSignatureEd25519, Ed25519, crypto.Hash(0) /* no pre-hashing */},
   379  }
   380  
   381  // hashToPSSParameters contains the DER encoded RSA PSS parameters for the
   382  // SHA256, SHA384, and SHA512 hashes as defined in RFC 3447, Appendix A.2.3.
   383  // The parameters contain the following values:
   384  //   - hashAlgorithm contains the associated hash identifier with NULL parameters
   385  //   - maskGenAlgorithm always contains the default mgf1SHA1 identifier
   386  //   - saltLength contains the length of the associated hash
   387  //   - trailerField always contains the default trailerFieldBC value
   388  var hashToPSSParameters = map[crypto.Hash]asn1.RawValue{
   389  	crypto.SHA256: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 162, 3, 2, 1, 32}},
   390  	crypto.SHA384: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 162, 3, 2, 1, 48}},
   391  	crypto.SHA512: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 162, 3, 2, 1, 64}},
   392  }
   393  
   394  // pssParameters reflects the parameters in an AlgorithmIdentifier that
   395  // specifies RSA PSS. See RFC 3447, Appendix A.2.3.
   396  type pssParameters struct {
   397  	// The following three fields are not marked as
   398  	// optional because the default values specify SHA-1,
   399  	// which is no longer suitable for use in signatures.
   400  	Hash         pkix.AlgorithmIdentifier `asn1:"explicit,tag:0"`
   401  	MGF          pkix.AlgorithmIdentifier `asn1:"explicit,tag:1"`
   402  	SaltLength   int                      `asn1:"explicit,tag:2"`
   403  	TrailerField int                      `asn1:"optional,explicit,tag:3,default:1"`
   404  }
   405  
   406  func getSignatureAlgorithmFromAI(ai pkix.AlgorithmIdentifier) SignatureAlgorithm {
   407  	if ai.Algorithm.Equal(oidSignatureEd25519) {
   408  		// RFC 8410, Section 3
   409  		// > For all of the OIDs, the parameters MUST be absent.
   410  		if len(ai.Parameters.FullBytes) != 0 {
   411  			return UnknownSignatureAlgorithm
   412  		}
   413  	}
   414  
   415  	if !ai.Algorithm.Equal(oidSignatureRSAPSS) {
   416  		for _, details := range signatureAlgorithmDetails {
   417  			if ai.Algorithm.Equal(details.oid) {
   418  				return details.algo
   419  			}
   420  		}
   421  		return UnknownSignatureAlgorithm
   422  	}
   423  
   424  	// RSA PSS is special because it encodes important parameters
   425  	// in the Parameters.
   426  
   427  	var params pssParameters
   428  	if _, err := asn1.Unmarshal(ai.Parameters.FullBytes, &params); err != nil {
   429  		return UnknownSignatureAlgorithm
   430  	}
   431  
   432  	var mgf1HashFunc pkix.AlgorithmIdentifier
   433  	if _, err := asn1.Unmarshal(params.MGF.Parameters.FullBytes, &mgf1HashFunc); err != nil {
   434  		return UnknownSignatureAlgorithm
   435  	}
   436  
   437  	// PSS is greatly overburdened with options. This code forces them into
   438  	// three buckets by requiring that the MGF1 hash function always match the
   439  	// message hash function (as recommended in RFC 3447, Section 8.1), that the
   440  	// salt length matches the hash length, and that the trailer field has the
   441  	// default value.
   442  	if (len(params.Hash.Parameters.FullBytes) != 0 && !bytes.Equal(params.Hash.Parameters.FullBytes, asn1.NullBytes)) ||
   443  		!params.MGF.Algorithm.Equal(oidMGF1) ||
   444  		!mgf1HashFunc.Algorithm.Equal(params.Hash.Algorithm) ||
   445  		(len(mgf1HashFunc.Parameters.FullBytes) != 0 && !bytes.Equal(mgf1HashFunc.Parameters.FullBytes, asn1.NullBytes)) ||
   446  		params.TrailerField != 1 {
   447  		return UnknownSignatureAlgorithm
   448  	}
   449  
   450  	switch {
   451  	case params.Hash.Algorithm.Equal(oidSHA256) && params.SaltLength == 32:
   452  		return SHA256WithRSAPSS
   453  	case params.Hash.Algorithm.Equal(oidSHA384) && params.SaltLength == 48:
   454  		return SHA384WithRSAPSS
   455  	case params.Hash.Algorithm.Equal(oidSHA512) && params.SaltLength == 64:
   456  		return SHA512WithRSAPSS
   457  	}
   458  
   459  	return UnknownSignatureAlgorithm
   460  }
   461  
   462  var (
   463  	// RFC 3279, 2.3 Public Key Algorithms
   464  	//
   465  	//	pkcs-1 OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
   466  	//		rsadsi(113549) pkcs(1) 1 }
   467  	//
   468  	// rsaEncryption OBJECT IDENTIFIER ::== { pkcs1-1 1 }
   469  	//
   470  	//	id-dsa OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
   471  	//		x9-57(10040) x9cm(4) 1 }
   472  	oidPublicKeyRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 1}
   473  	oidPublicKeyDSA = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 1}
   474  	// RFC 5480, 2.1.1 Unrestricted Algorithm Identifier and Parameters
   475  	//
   476  	//	id-ecPublicKey OBJECT IDENTIFIER ::= {
   477  	//		iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2) 1 }
   478  	oidPublicKeyECDSA = asn1.ObjectIdentifier{1, 2, 840, 10045, 2, 1}
   479  	// RFC 8410, Section 3
   480  	//
   481  	//	id-X25519    OBJECT IDENTIFIER ::= { 1 3 101 110 }
   482  	//	id-Ed25519   OBJECT IDENTIFIER ::= { 1 3 101 112 }
   483  	oidPublicKeyX25519  = asn1.ObjectIdentifier{1, 3, 101, 110}
   484  	oidPublicKeyEd25519 = asn1.ObjectIdentifier{1, 3, 101, 112}
   485  )
   486  
   487  // getPublicKeyAlgorithmFromOID returns the exposed PublicKeyAlgorithm
   488  // identifier for public key types supported in certificates and CSRs. Marshal
   489  // and Parse functions may support a different set of public key types.
   490  func getPublicKeyAlgorithmFromOID(oid asn1.ObjectIdentifier) PublicKeyAlgorithm {
   491  	switch {
   492  	case oid.Equal(oidPublicKeyRSA):
   493  		return RSA
   494  	case oid.Equal(oidPublicKeyDSA):
   495  		return DSA
   496  	case oid.Equal(oidPublicKeyECDSA):
   497  		return ECDSA
   498  	case oid.Equal(oidPublicKeyEd25519):
   499  		return Ed25519
   500  	}
   501  	return UnknownPublicKeyAlgorithm
   502  }
   503  
   504  // RFC 5480, 2.1.1.1. Named Curve
   505  //
   506  //	secp224r1 OBJECT IDENTIFIER ::= {
   507  //	  iso(1) identified-organization(3) certicom(132) curve(0) 33 }
   508  //
   509  //	secp256r1 OBJECT IDENTIFIER ::= {
   510  //	  iso(1) member-body(2) us(840) ansi-X9-62(10045) curves(3)
   511  //	  prime(1) 7 }
   512  //
   513  //	secp384r1 OBJECT IDENTIFIER ::= {
   514  //	  iso(1) identified-organization(3) certicom(132) curve(0) 34 }
   515  //
   516  //	secp521r1 OBJECT IDENTIFIER ::= {
   517  //	  iso(1) identified-organization(3) certicom(132) curve(0) 35 }
   518  //
   519  // NB: secp256r1 is equivalent to prime256v1
   520  var (
   521  	oidNamedCurveP224 = asn1.ObjectIdentifier{1, 3, 132, 0, 33}
   522  	oidNamedCurveP256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 3, 1, 7}
   523  	oidNamedCurveP384 = asn1.ObjectIdentifier{1, 3, 132, 0, 34}
   524  	oidNamedCurveP521 = asn1.ObjectIdentifier{1, 3, 132, 0, 35}
   525  )
   526  
   527  func namedCurveFromOID(oid asn1.ObjectIdentifier) elliptic.Curve {
   528  	switch {
   529  	case oid.Equal(oidNamedCurveP224):
   530  		return elliptic.P224()
   531  	case oid.Equal(oidNamedCurveP256):
   532  		return elliptic.P256()
   533  	case oid.Equal(oidNamedCurveP384):
   534  		return elliptic.P384()
   535  	case oid.Equal(oidNamedCurveP521):
   536  		return elliptic.P521()
   537  	}
   538  	return nil
   539  }
   540  
   541  func oidFromNamedCurve(curve elliptic.Curve) (asn1.ObjectIdentifier, bool) {
   542  	switch curve {
   543  	case elliptic.P224():
   544  		return oidNamedCurveP224, true
   545  	case elliptic.P256():
   546  		return oidNamedCurveP256, true
   547  	case elliptic.P384():
   548  		return oidNamedCurveP384, true
   549  	case elliptic.P521():
   550  		return oidNamedCurveP521, true
   551  	}
   552  
   553  	return nil, false
   554  }
   555  
   556  func oidFromECDHCurve(curve ecdh.Curve) (asn1.ObjectIdentifier, bool) {
   557  	switch curve {
   558  	case ecdh.X25519():
   559  		return oidPublicKeyX25519, true
   560  	case ecdh.P256():
   561  		return oidNamedCurveP256, true
   562  	case ecdh.P384():
   563  		return oidNamedCurveP384, true
   564  	case ecdh.P521():
   565  		return oidNamedCurveP521, true
   566  	}
   567  
   568  	return nil, false
   569  }
   570  
   571  // KeyUsage represents the set of actions that are valid for a given key. It's
   572  // a bitmap of the KeyUsage* constants.
   573  type KeyUsage int
   574  
   575  const (
   576  	KeyUsageDigitalSignature KeyUsage = 1 << iota
   577  	KeyUsageContentCommitment
   578  	KeyUsageKeyEncipherment
   579  	KeyUsageDataEncipherment
   580  	KeyUsageKeyAgreement
   581  	KeyUsageCertSign
   582  	KeyUsageCRLSign
   583  	KeyUsageEncipherOnly
   584  	KeyUsageDecipherOnly
   585  )
   586  
   587  // RFC 5280, 4.2.1.12  Extended Key Usage
   588  //
   589  //	anyExtendedKeyUsage OBJECT IDENTIFIER ::= { id-ce-extKeyUsage 0 }
   590  //
   591  //	id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
   592  //
   593  //	id-kp-serverAuth             OBJECT IDENTIFIER ::= { id-kp 1 }
   594  //	id-kp-clientAuth             OBJECT IDENTIFIER ::= { id-kp 2 }
   595  //	id-kp-codeSigning            OBJECT IDENTIFIER ::= { id-kp 3 }
   596  //	id-kp-emailProtection        OBJECT IDENTIFIER ::= { id-kp 4 }
   597  //	id-kp-timeStamping           OBJECT IDENTIFIER ::= { id-kp 8 }
   598  //	id-kp-OCSPSigning            OBJECT IDENTIFIER ::= { id-kp 9 }
   599  var (
   600  	oidExtKeyUsageAny                            = asn1.ObjectIdentifier{2, 5, 29, 37, 0}
   601  	oidExtKeyUsageServerAuth                     = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 1}
   602  	oidExtKeyUsageClientAuth                     = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 2}
   603  	oidExtKeyUsageCodeSigning                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 3}
   604  	oidExtKeyUsageEmailProtection                = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 4}
   605  	oidExtKeyUsageIPSECEndSystem                 = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 5}
   606  	oidExtKeyUsageIPSECTunnel                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 6}
   607  	oidExtKeyUsageIPSECUser                      = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 7}
   608  	oidExtKeyUsageTimeStamping                   = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 8}
   609  	oidExtKeyUsageOCSPSigning                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 9}
   610  	oidExtKeyUsageMicrosoftServerGatedCrypto     = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 10, 3, 3}
   611  	oidExtKeyUsageNetscapeServerGatedCrypto      = asn1.ObjectIdentifier{2, 16, 840, 1, 113730, 4, 1}
   612  	oidExtKeyUsageMicrosoftCommercialCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 2, 1, 22}
   613  	oidExtKeyUsageMicrosoftKernelCodeSigning     = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 61, 1, 1}
   614  )
   615  
   616  // ExtKeyUsage represents an extended set of actions that are valid for a given key.
   617  // Each of the ExtKeyUsage* constants define a unique action.
   618  type ExtKeyUsage int
   619  
   620  const (
   621  	ExtKeyUsageAny ExtKeyUsage = iota
   622  	ExtKeyUsageServerAuth
   623  	ExtKeyUsageClientAuth
   624  	ExtKeyUsageCodeSigning
   625  	ExtKeyUsageEmailProtection
   626  	ExtKeyUsageIPSECEndSystem
   627  	ExtKeyUsageIPSECTunnel
   628  	ExtKeyUsageIPSECUser
   629  	ExtKeyUsageTimeStamping
   630  	ExtKeyUsageOCSPSigning
   631  	ExtKeyUsageMicrosoftServerGatedCrypto
   632  	ExtKeyUsageNetscapeServerGatedCrypto
   633  	ExtKeyUsageMicrosoftCommercialCodeSigning
   634  	ExtKeyUsageMicrosoftKernelCodeSigning
   635  )
   636  
   637  // extKeyUsageOIDs contains the mapping between an ExtKeyUsage and its OID.
   638  var extKeyUsageOIDs = []struct {
   639  	extKeyUsage ExtKeyUsage
   640  	oid         asn1.ObjectIdentifier
   641  }{
   642  	{ExtKeyUsageAny, oidExtKeyUsageAny},
   643  	{ExtKeyUsageServerAuth, oidExtKeyUsageServerAuth},
   644  	{ExtKeyUsageClientAuth, oidExtKeyUsageClientAuth},
   645  	{ExtKeyUsageCodeSigning, oidExtKeyUsageCodeSigning},
   646  	{ExtKeyUsageEmailProtection, oidExtKeyUsageEmailProtection},
   647  	{ExtKeyUsageIPSECEndSystem, oidExtKeyUsageIPSECEndSystem},
   648  	{ExtKeyUsageIPSECTunnel, oidExtKeyUsageIPSECTunnel},
   649  	{ExtKeyUsageIPSECUser, oidExtKeyUsageIPSECUser},
   650  	{ExtKeyUsageTimeStamping, oidExtKeyUsageTimeStamping},
   651  	{ExtKeyUsageOCSPSigning, oidExtKeyUsageOCSPSigning},
   652  	{ExtKeyUsageMicrosoftServerGatedCrypto, oidExtKeyUsageMicrosoftServerGatedCrypto},
   653  	{ExtKeyUsageNetscapeServerGatedCrypto, oidExtKeyUsageNetscapeServerGatedCrypto},
   654  	{ExtKeyUsageMicrosoftCommercialCodeSigning, oidExtKeyUsageMicrosoftCommercialCodeSigning},
   655  	{ExtKeyUsageMicrosoftKernelCodeSigning, oidExtKeyUsageMicrosoftKernelCodeSigning},
   656  }
   657  
   658  func extKeyUsageFromOID(oid asn1.ObjectIdentifier) (eku ExtKeyUsage, ok bool) {
   659  	for _, pair := range extKeyUsageOIDs {
   660  		if oid.Equal(pair.oid) {
   661  			return pair.extKeyUsage, true
   662  		}
   663  	}
   664  	return
   665  }
   666  
   667  func oidFromExtKeyUsage(eku ExtKeyUsage) (oid asn1.ObjectIdentifier, ok bool) {
   668  	for _, pair := range extKeyUsageOIDs {
   669  		if eku == pair.extKeyUsage {
   670  			return pair.oid, true
   671  		}
   672  	}
   673  	return
   674  }
   675  
   676  // A Certificate represents an X.509 certificate.
   677  type Certificate struct {
   678  	Raw                     []byte // Complete ASN.1 DER content (certificate, signature algorithm and signature).
   679  	RawTBSCertificate       []byte // Certificate part of raw ASN.1 DER content.
   680  	RawSubjectPublicKeyInfo []byte // DER encoded SubjectPublicKeyInfo.
   681  	RawSubject              []byte // DER encoded Subject
   682  	RawIssuer               []byte // DER encoded Issuer
   683  
   684  	Signature          []byte
   685  	SignatureAlgorithm SignatureAlgorithm
   686  
   687  	PublicKeyAlgorithm PublicKeyAlgorithm
   688  	PublicKey          any
   689  
   690  	Version             int
   691  	SerialNumber        *big.Int
   692  	Issuer              pkix.Name
   693  	Subject             pkix.Name
   694  	NotBefore, NotAfter time.Time // Validity bounds.
   695  	KeyUsage            KeyUsage
   696  
   697  	// Extensions contains raw X.509 extensions. When parsing certificates,
   698  	// this can be used to extract non-critical extensions that are not
   699  	// parsed by this package. When marshaling certificates, the Extensions
   700  	// field is ignored, see ExtraExtensions.
   701  	Extensions []pkix.Extension
   702  
   703  	// ExtraExtensions contains extensions to be copied, raw, into any
   704  	// marshaled certificates. Values override any extensions that would
   705  	// otherwise be produced based on the other fields. The ExtraExtensions
   706  	// field is not populated when parsing certificates, see Extensions.
   707  	ExtraExtensions []pkix.Extension
   708  
   709  	// UnhandledCriticalExtensions contains a list of extension IDs that
   710  	// were not (fully) processed when parsing. Verify will fail if this
   711  	// slice is non-empty, unless verification is delegated to an OS
   712  	// library which understands all the critical extensions.
   713  	//
   714  	// Users can access these extensions using Extensions and can remove
   715  	// elements from this slice if they believe that they have been
   716  	// handled.
   717  	UnhandledCriticalExtensions []asn1.ObjectIdentifier
   718  
   719  	ExtKeyUsage        []ExtKeyUsage           // Sequence of extended key usages.
   720  	UnknownExtKeyUsage []asn1.ObjectIdentifier // Encountered extended key usages unknown to this package.
   721  
   722  	// BasicConstraintsValid indicates whether IsCA, MaxPathLen,
   723  	// and MaxPathLenZero are valid.
   724  	BasicConstraintsValid bool
   725  	IsCA                  bool
   726  
   727  	// MaxPathLen and MaxPathLenZero indicate the presence and
   728  	// value of the BasicConstraints' "pathLenConstraint".
   729  	//
   730  	// When parsing a certificate, a positive non-zero MaxPathLen
   731  	// means that the field was specified, -1 means it was unset,
   732  	// and MaxPathLenZero being true mean that the field was
   733  	// explicitly set to zero. The case of MaxPathLen==0 with MaxPathLenZero==false
   734  	// should be treated equivalent to -1 (unset).
   735  	//
   736  	// When generating a certificate, an unset pathLenConstraint
   737  	// can be requested with either MaxPathLen == -1 or using the
   738  	// zero value for both MaxPathLen and MaxPathLenZero.
   739  	MaxPathLen int
   740  	// MaxPathLenZero indicates that BasicConstraintsValid==true
   741  	// and MaxPathLen==0 should be interpreted as an actual
   742  	// maximum path length of zero. Otherwise, that combination is
   743  	// interpreted as MaxPathLen not being set.
   744  	MaxPathLenZero bool
   745  
   746  	SubjectKeyId   []byte
   747  	AuthorityKeyId []byte
   748  
   749  	// RFC 5280, 4.2.2.1 (Authority Information Access)
   750  	OCSPServer            []string
   751  	IssuingCertificateURL []string
   752  
   753  	// Subject Alternate Name values. (Note that these values may not be valid
   754  	// if invalid values were contained within a parsed certificate. For
   755  	// example, an element of DNSNames may not be a valid DNS domain name.)
   756  	DNSNames       []string
   757  	EmailAddresses []string
   758  	IPAddresses    []net.IP
   759  	URIs           []*url.URL
   760  
   761  	// Name constraints
   762  	PermittedDNSDomainsCritical bool // if true then the name constraints are marked critical.
   763  	PermittedDNSDomains         []string
   764  	ExcludedDNSDomains          []string
   765  	PermittedIPRanges           []*net.IPNet
   766  	ExcludedIPRanges            []*net.IPNet
   767  	PermittedEmailAddresses     []string
   768  	ExcludedEmailAddresses      []string
   769  	PermittedURIDomains         []string
   770  	ExcludedURIDomains          []string
   771  
   772  	// CRL Distribution Points
   773  	CRLDistributionPoints []string
   774  
   775  	// PolicyIdentifiers contains asn1.ObjectIdentifiers, the components
   776  	// of which are limited to int32. If a certificate contains a policy which
   777  	// cannot be represented by asn1.ObjectIdentifier, it will not be included in
   778  	// PolicyIdentifiers, but will be present in Policies, which contains all parsed
   779  	// policy OIDs.
   780  	PolicyIdentifiers []asn1.ObjectIdentifier
   781  
   782  	// Policies contains all policy identifiers included in the certificate.
   783  	// In Go 1.22, encoding/gob cannot handle and ignores this field.
   784  	Policies []OID
   785  }
   786  
   787  // ErrUnsupportedAlgorithm results from attempting to perform an operation that
   788  // involves algorithms that are not currently implemented.
   789  var ErrUnsupportedAlgorithm = errors.New("x509: cannot verify signature: algorithm unimplemented")
   790  
   791  // An InsecureAlgorithmError indicates that the [SignatureAlgorithm] used to
   792  // generate the signature is not secure, and the signature has been rejected.
   793  //
   794  // To temporarily restore support for SHA-1 signatures, include the value
   795  // "x509sha1=1" in the GODEBUG environment variable. Note that this option will
   796  // be removed in a future release.
   797  type InsecureAlgorithmError SignatureAlgorithm
   798  
   799  func (e InsecureAlgorithmError) Error() string {
   800  	var override string
   801  	if SignatureAlgorithm(e) == SHA1WithRSA || SignatureAlgorithm(e) == ECDSAWithSHA1 {
   802  		override = " (temporarily override with GODEBUG=x509sha1=1)"
   803  	}
   804  	return fmt.Sprintf("x509: cannot verify signature: insecure algorithm %v", SignatureAlgorithm(e)) + override
   805  }
   806  
   807  // ConstraintViolationError results when a requested usage is not permitted by
   808  // a certificate. For example: checking a signature when the public key isn't a
   809  // certificate signing key.
   810  type ConstraintViolationError struct{}
   811  
   812  func (ConstraintViolationError) Error() string {
   813  	return "x509: invalid signature: parent certificate cannot sign this kind of certificate"
   814  }
   815  
   816  func (c *Certificate) Equal(other *Certificate) bool {
   817  	if c == nil || other == nil {
   818  		return c == other
   819  	}
   820  	return bytes.Equal(c.Raw, other.Raw)
   821  }
   822  
   823  func (c *Certificate) hasSANExtension() bool {
   824  	return oidInExtensions(oidExtensionSubjectAltName, c.Extensions)
   825  }
   826  
   827  // CheckSignatureFrom verifies that the signature on c is a valid signature from parent.
   828  //
   829  // This is a low-level API that performs very limited checks, and not a full
   830  // path verifier. Most users should use [Certificate.Verify] instead.
   831  func (c *Certificate) CheckSignatureFrom(parent *Certificate) error {
   832  	// RFC 5280, 4.2.1.9:
   833  	// "If the basic constraints extension is not present in a version 3
   834  	// certificate, or the extension is present but the cA boolean is not
   835  	// asserted, then the certified public key MUST NOT be used to verify
   836  	// certificate signatures."
   837  	if parent.Version == 3 && !parent.BasicConstraintsValid ||
   838  		parent.BasicConstraintsValid && !parent.IsCA {
   839  		return ConstraintViolationError{}
   840  	}
   841  
   842  	if parent.KeyUsage != 0 && parent.KeyUsage&KeyUsageCertSign == 0 {
   843  		return ConstraintViolationError{}
   844  	}
   845  
   846  	if parent.PublicKeyAlgorithm == UnknownPublicKeyAlgorithm {
   847  		return ErrUnsupportedAlgorithm
   848  	}
   849  
   850  	return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificate, c.Signature, parent.PublicKey, false)
   851  }
   852  
   853  // CheckSignature verifies that signature is a valid signature over signed from
   854  // c's public key.
   855  //
   856  // This is a low-level API that performs no validity checks on the certificate.
   857  //
   858  // [MD5WithRSA] signatures are rejected, while [SHA1WithRSA] and [ECDSAWithSHA1]
   859  // signatures are currently accepted.
   860  func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) error {
   861  	return checkSignature(algo, signed, signature, c.PublicKey, true)
   862  }
   863  
   864  func (c *Certificate) hasNameConstraints() bool {
   865  	return oidInExtensions(oidExtensionNameConstraints, c.Extensions)
   866  }
   867  
   868  func (c *Certificate) getSANExtension() []byte {
   869  	for _, e := range c.Extensions {
   870  		if e.Id.Equal(oidExtensionSubjectAltName) {
   871  			return e.Value
   872  		}
   873  	}
   874  	return nil
   875  }
   876  
   877  func signaturePublicKeyAlgoMismatchError(expectedPubKeyAlgo PublicKeyAlgorithm, pubKey any) error {
   878  	return fmt.Errorf("x509: signature algorithm specifies an %s public key, but have public key of type %T", expectedPubKeyAlgo.String(), pubKey)
   879  }
   880  
   881  var x509sha1 = godebug.New("x509sha1")
   882  
   883  // checkSignature verifies that signature is a valid signature over signed from
   884  // a crypto.PublicKey.
   885  func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey crypto.PublicKey, allowSHA1 bool) (err error) {
   886  	var hashType crypto.Hash
   887  	var pubKeyAlgo PublicKeyAlgorithm
   888  
   889  	for _, details := range signatureAlgorithmDetails {
   890  		if details.algo == algo {
   891  			hashType = details.hash
   892  			pubKeyAlgo = details.pubKeyAlgo
   893  			break
   894  		}
   895  	}
   896  
   897  	switch hashType {
   898  	case crypto.Hash(0):
   899  		if pubKeyAlgo != Ed25519 {
   900  			return ErrUnsupportedAlgorithm
   901  		}
   902  	case crypto.MD5:
   903  		return InsecureAlgorithmError(algo)
   904  	case crypto.SHA1:
   905  		// SHA-1 signatures are mostly disabled. See go.dev/issue/41682.
   906  		if !allowSHA1 {
   907  			if x509sha1.Value() != "1" {
   908  				return InsecureAlgorithmError(algo)
   909  			}
   910  			x509sha1.IncNonDefault()
   911  		}
   912  		fallthrough
   913  	default:
   914  		if !hashType.Available() {
   915  			return ErrUnsupportedAlgorithm
   916  		}
   917  		h := hashType.New()
   918  		h.Write(signed)
   919  		signed = h.Sum(nil)
   920  	}
   921  
   922  	switch pub := publicKey.(type) {
   923  	case *rsa.PublicKey:
   924  		if pubKeyAlgo != RSA {
   925  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
   926  		}
   927  		if algo.isRSAPSS() {
   928  			return rsa.VerifyPSS(pub, hashType, signed, signature, &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash})
   929  		} else {
   930  			return rsa.VerifyPKCS1v15(pub, hashType, signed, signature)
   931  		}
   932  	case *ecdsa.PublicKey:
   933  		if pubKeyAlgo != ECDSA {
   934  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
   935  		}
   936  		if !ecdsa.VerifyASN1(pub, signed, signature) {
   937  			return errors.New("x509: ECDSA verification failure")
   938  		}
   939  		return
   940  	case ed25519.PublicKey:
   941  		if pubKeyAlgo != Ed25519 {
   942  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
   943  		}
   944  		if !ed25519.Verify(pub, signed, signature) {
   945  			return errors.New("x509: Ed25519 verification failure")
   946  		}
   947  		return
   948  	}
   949  	return ErrUnsupportedAlgorithm
   950  }
   951  
   952  // CheckCRLSignature checks that the signature in crl is from c.
   953  //
   954  // Deprecated: Use [RevocationList.CheckSignatureFrom] instead.
   955  func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) error {
   956  	algo := getSignatureAlgorithmFromAI(crl.SignatureAlgorithm)
   957  	return c.CheckSignature(algo, crl.TBSCertList.Raw, crl.SignatureValue.RightAlign())
   958  }
   959  
   960  type UnhandledCriticalExtension struct{}
   961  
   962  func (h UnhandledCriticalExtension) Error() string {
   963  	return "x509: unhandled critical extension"
   964  }
   965  
   966  type basicConstraints struct {
   967  	IsCA       bool `asn1:"optional"`
   968  	MaxPathLen int  `asn1:"optional,default:-1"`
   969  }
   970  
   971  // RFC 5280 4.2.1.4
   972  type policyInformation struct {
   973  	Policy asn1.ObjectIdentifier
   974  	// policyQualifiers omitted
   975  }
   976  
   977  const (
   978  	nameTypeEmail = 1
   979  	nameTypeDNS   = 2
   980  	nameTypeURI   = 6
   981  	nameTypeIP    = 7
   982  )
   983  
   984  // RFC 5280, 4.2.2.1
   985  type authorityInfoAccess struct {
   986  	Method   asn1.ObjectIdentifier
   987  	Location asn1.RawValue
   988  }
   989  
   990  // RFC 5280, 4.2.1.14
   991  type distributionPoint struct {
   992  	DistributionPoint distributionPointName `asn1:"optional,tag:0"`
   993  	Reason            asn1.BitString        `asn1:"optional,tag:1"`
   994  	CRLIssuer         asn1.RawValue         `asn1:"optional,tag:2"`
   995  }
   996  
   997  type distributionPointName struct {
   998  	FullName     []asn1.RawValue  `asn1:"optional,tag:0"`
   999  	RelativeName pkix.RDNSequence `asn1:"optional,tag:1"`
  1000  }
  1001  
  1002  func reverseBitsInAByte(in byte) byte {
  1003  	b1 := in>>4 | in<<4
  1004  	b2 := b1>>2&0x33 | b1<<2&0xcc
  1005  	b3 := b2>>1&0x55 | b2<<1&0xaa
  1006  	return b3
  1007  }
  1008  
  1009  // asn1BitLength returns the bit-length of bitString by considering the
  1010  // most-significant bit in a byte to be the "first" bit. This convention
  1011  // matches ASN.1, but differs from almost everything else.
  1012  func asn1BitLength(bitString []byte) int {
  1013  	bitLen := len(bitString) * 8
  1014  
  1015  	for i := range bitString {
  1016  		b := bitString[len(bitString)-i-1]
  1017  
  1018  		for bit := uint(0); bit < 8; bit++ {
  1019  			if (b>>bit)&1 == 1 {
  1020  				return bitLen
  1021  			}
  1022  			bitLen--
  1023  		}
  1024  	}
  1025  
  1026  	return 0
  1027  }
  1028  
  1029  var (
  1030  	oidExtensionSubjectKeyId          = []int{2, 5, 29, 14}
  1031  	oidExtensionKeyUsage              = []int{2, 5, 29, 15}
  1032  	oidExtensionExtendedKeyUsage      = []int{2, 5, 29, 37}
  1033  	oidExtensionAuthorityKeyId        = []int{2, 5, 29, 35}
  1034  	oidExtensionBasicConstraints      = []int{2, 5, 29, 19}
  1035  	oidExtensionSubjectAltName        = []int{2, 5, 29, 17}
  1036  	oidExtensionCertificatePolicies   = []int{2, 5, 29, 32}
  1037  	oidExtensionNameConstraints       = []int{2, 5, 29, 30}
  1038  	oidExtensionCRLDistributionPoints = []int{2, 5, 29, 31}
  1039  	oidExtensionAuthorityInfoAccess   = []int{1, 3, 6, 1, 5, 5, 7, 1, 1}
  1040  	oidExtensionCRLNumber             = []int{2, 5, 29, 20}
  1041  	oidExtensionReasonCode            = []int{2, 5, 29, 21}
  1042  )
  1043  
  1044  var (
  1045  	oidAuthorityInfoAccessOcsp    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 1}
  1046  	oidAuthorityInfoAccessIssuers = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 2}
  1047  )
  1048  
  1049  // oidInExtensions reports whether an extension with the given oid exists in
  1050  // extensions.
  1051  func oidInExtensions(oid asn1.ObjectIdentifier, extensions []pkix.Extension) bool {
  1052  	for _, e := range extensions {
  1053  		if e.Id.Equal(oid) {
  1054  			return true
  1055  		}
  1056  	}
  1057  	return false
  1058  }
  1059  
  1060  // marshalSANs marshals a list of addresses into a the contents of an X.509
  1061  // SubjectAlternativeName extension.
  1062  func marshalSANs(dnsNames, emailAddresses []string, ipAddresses []net.IP, uris []*url.URL) (derBytes []byte, err error) {
  1063  	var rawValues []asn1.RawValue
  1064  	for _, name := range dnsNames {
  1065  		if err := isIA5String(name); err != nil {
  1066  			return nil, err
  1067  		}
  1068  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeDNS, Class: 2, Bytes: []byte(name)})
  1069  	}
  1070  	for _, email := range emailAddresses {
  1071  		if err := isIA5String(email); err != nil {
  1072  			return nil, err
  1073  		}
  1074  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeEmail, Class: 2, Bytes: []byte(email)})
  1075  	}
  1076  	for _, rawIP := range ipAddresses {
  1077  		// If possible, we always want to encode IPv4 addresses in 4 bytes.
  1078  		ip := rawIP.To4()
  1079  		if ip == nil {
  1080  			ip = rawIP
  1081  		}
  1082  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeIP, Class: 2, Bytes: ip})
  1083  	}
  1084  	for _, uri := range uris {
  1085  		uriStr := uri.String()
  1086  		if err := isIA5String(uriStr); err != nil {
  1087  			return nil, err
  1088  		}
  1089  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeURI, Class: 2, Bytes: []byte(uriStr)})
  1090  	}
  1091  	return asn1.Marshal(rawValues)
  1092  }
  1093  
  1094  func isIA5String(s string) error {
  1095  	for _, r := range s {
  1096  		// Per RFC5280 "IA5String is limited to the set of ASCII characters"
  1097  		if r > unicode.MaxASCII {
  1098  			return fmt.Errorf("x509: %q cannot be encoded as an IA5String", s)
  1099  		}
  1100  	}
  1101  
  1102  	return nil
  1103  }
  1104  
  1105  var usePoliciesField = godebug.New("x509usepolicies")
  1106  
  1107  func buildCertExtensions(template *Certificate, subjectIsEmpty bool, authorityKeyId []byte, subjectKeyId []byte) (ret []pkix.Extension, err error) {
  1108  	ret = make([]pkix.Extension, 10 /* maximum number of elements. */)
  1109  	n := 0
  1110  
  1111  	if template.KeyUsage != 0 &&
  1112  		!oidInExtensions(oidExtensionKeyUsage, template.ExtraExtensions) {
  1113  		ret[n], err = marshalKeyUsage(template.KeyUsage)
  1114  		if err != nil {
  1115  			return nil, err
  1116  		}
  1117  		n++
  1118  	}
  1119  
  1120  	if (len(template.ExtKeyUsage) > 0 || len(template.UnknownExtKeyUsage) > 0) &&
  1121  		!oidInExtensions(oidExtensionExtendedKeyUsage, template.ExtraExtensions) {
  1122  		ret[n], err = marshalExtKeyUsage(template.ExtKeyUsage, template.UnknownExtKeyUsage)
  1123  		if err != nil {
  1124  			return nil, err
  1125  		}
  1126  		n++
  1127  	}
  1128  
  1129  	if template.BasicConstraintsValid && !oidInExtensions(oidExtensionBasicConstraints, template.ExtraExtensions) {
  1130  		ret[n], err = marshalBasicConstraints(template.IsCA, template.MaxPathLen, template.MaxPathLenZero)
  1131  		if err != nil {
  1132  			return nil, err
  1133  		}
  1134  		n++
  1135  	}
  1136  
  1137  	if len(subjectKeyId) > 0 && !oidInExtensions(oidExtensionSubjectKeyId, template.ExtraExtensions) {
  1138  		ret[n].Id = oidExtensionSubjectKeyId
  1139  		ret[n].Value, err = asn1.Marshal(subjectKeyId)
  1140  		if err != nil {
  1141  			return
  1142  		}
  1143  		n++
  1144  	}
  1145  
  1146  	if len(authorityKeyId) > 0 && !oidInExtensions(oidExtensionAuthorityKeyId, template.ExtraExtensions) {
  1147  		ret[n].Id = oidExtensionAuthorityKeyId
  1148  		ret[n].Value, err = asn1.Marshal(authKeyId{authorityKeyId})
  1149  		if err != nil {
  1150  			return
  1151  		}
  1152  		n++
  1153  	}
  1154  
  1155  	if (len(template.OCSPServer) > 0 || len(template.IssuingCertificateURL) > 0) &&
  1156  		!oidInExtensions(oidExtensionAuthorityInfoAccess, template.ExtraExtensions) {
  1157  		ret[n].Id = oidExtensionAuthorityInfoAccess
  1158  		var aiaValues []authorityInfoAccess
  1159  		for _, name := range template.OCSPServer {
  1160  			aiaValues = append(aiaValues, authorityInfoAccess{
  1161  				Method:   oidAuthorityInfoAccessOcsp,
  1162  				Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
  1163  			})
  1164  		}
  1165  		for _, name := range template.IssuingCertificateURL {
  1166  			aiaValues = append(aiaValues, authorityInfoAccess{
  1167  				Method:   oidAuthorityInfoAccessIssuers,
  1168  				Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
  1169  			})
  1170  		}
  1171  		ret[n].Value, err = asn1.Marshal(aiaValues)
  1172  		if err != nil {
  1173  			return
  1174  		}
  1175  		n++
  1176  	}
  1177  
  1178  	if (len(template.DNSNames) > 0 || len(template.EmailAddresses) > 0 || len(template.IPAddresses) > 0 || len(template.URIs) > 0) &&
  1179  		!oidInExtensions(oidExtensionSubjectAltName, template.ExtraExtensions) {
  1180  		ret[n].Id = oidExtensionSubjectAltName
  1181  		// From RFC 5280, Section 4.2.1.6:
  1182  		// “If the subject field contains an empty sequence ... then
  1183  		// subjectAltName extension ... is marked as critical”
  1184  		ret[n].Critical = subjectIsEmpty
  1185  		ret[n].Value, err = marshalSANs(template.DNSNames, template.EmailAddresses, template.IPAddresses, template.URIs)
  1186  		if err != nil {
  1187  			return
  1188  		}
  1189  		n++
  1190  	}
  1191  
  1192  	usePolicies := usePoliciesField.Value() == "1"
  1193  	if ((!usePolicies && len(template.PolicyIdentifiers) > 0) || (usePolicies && len(template.Policies) > 0)) &&
  1194  		!oidInExtensions(oidExtensionCertificatePolicies, template.ExtraExtensions) {
  1195  		ret[n], err = marshalCertificatePolicies(template.Policies, template.PolicyIdentifiers)
  1196  		if err != nil {
  1197  			return nil, err
  1198  		}
  1199  		n++
  1200  	}
  1201  
  1202  	if (len(template.PermittedDNSDomains) > 0 || len(template.ExcludedDNSDomains) > 0 ||
  1203  		len(template.PermittedIPRanges) > 0 || len(template.ExcludedIPRanges) > 0 ||
  1204  		len(template.PermittedEmailAddresses) > 0 || len(template.ExcludedEmailAddresses) > 0 ||
  1205  		len(template.PermittedURIDomains) > 0 || len(template.ExcludedURIDomains) > 0) &&
  1206  		!oidInExtensions(oidExtensionNameConstraints, template.ExtraExtensions) {
  1207  		ret[n].Id = oidExtensionNameConstraints
  1208  		ret[n].Critical = template.PermittedDNSDomainsCritical
  1209  
  1210  		ipAndMask := func(ipNet *net.IPNet) []byte {
  1211  			maskedIP := ipNet.IP.Mask(ipNet.Mask)
  1212  			ipAndMask := make([]byte, 0, len(maskedIP)+len(ipNet.Mask))
  1213  			ipAndMask = append(ipAndMask, maskedIP...)
  1214  			ipAndMask = append(ipAndMask, ipNet.Mask...)
  1215  			return ipAndMask
  1216  		}
  1217  
  1218  		serialiseConstraints := func(dns []string, ips []*net.IPNet, emails []string, uriDomains []string) (der []byte, err error) {
  1219  			var b cryptobyte.Builder
  1220  
  1221  			for _, name := range dns {
  1222  				if err = isIA5String(name); err != nil {
  1223  					return nil, err
  1224  				}
  1225  
  1226  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1227  					b.AddASN1(cryptobyte_asn1.Tag(2).ContextSpecific(), func(b *cryptobyte.Builder) {
  1228  						b.AddBytes([]byte(name))
  1229  					})
  1230  				})
  1231  			}
  1232  
  1233  			for _, ipNet := range ips {
  1234  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1235  					b.AddASN1(cryptobyte_asn1.Tag(7).ContextSpecific(), func(b *cryptobyte.Builder) {
  1236  						b.AddBytes(ipAndMask(ipNet))
  1237  					})
  1238  				})
  1239  			}
  1240  
  1241  			for _, email := range emails {
  1242  				if err = isIA5String(email); err != nil {
  1243  					return nil, err
  1244  				}
  1245  
  1246  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1247  					b.AddASN1(cryptobyte_asn1.Tag(1).ContextSpecific(), func(b *cryptobyte.Builder) {
  1248  						b.AddBytes([]byte(email))
  1249  					})
  1250  				})
  1251  			}
  1252  
  1253  			for _, uriDomain := range uriDomains {
  1254  				if err = isIA5String(uriDomain); err != nil {
  1255  					return nil, err
  1256  				}
  1257  
  1258  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1259  					b.AddASN1(cryptobyte_asn1.Tag(6).ContextSpecific(), func(b *cryptobyte.Builder) {
  1260  						b.AddBytes([]byte(uriDomain))
  1261  					})
  1262  				})
  1263  			}
  1264  
  1265  			return b.Bytes()
  1266  		}
  1267  
  1268  		permitted, err := serialiseConstraints(template.PermittedDNSDomains, template.PermittedIPRanges, template.PermittedEmailAddresses, template.PermittedURIDomains)
  1269  		if err != nil {
  1270  			return nil, err
  1271  		}
  1272  
  1273  		excluded, err := serialiseConstraints(template.ExcludedDNSDomains, template.ExcludedIPRanges, template.ExcludedEmailAddresses, template.ExcludedURIDomains)
  1274  		if err != nil {
  1275  			return nil, err
  1276  		}
  1277  
  1278  		var b cryptobyte.Builder
  1279  		b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1280  			if len(permitted) > 0 {
  1281  				b.AddASN1(cryptobyte_asn1.Tag(0).ContextSpecific().Constructed(), func(b *cryptobyte.Builder) {
  1282  					b.AddBytes(permitted)
  1283  				})
  1284  			}
  1285  
  1286  			if len(excluded) > 0 {
  1287  				b.AddASN1(cryptobyte_asn1.Tag(1).ContextSpecific().Constructed(), func(b *cryptobyte.Builder) {
  1288  					b.AddBytes(excluded)
  1289  				})
  1290  			}
  1291  		})
  1292  
  1293  		ret[n].Value, err = b.Bytes()
  1294  		if err != nil {
  1295  			return nil, err
  1296  		}
  1297  		n++
  1298  	}
  1299  
  1300  	if len(template.CRLDistributionPoints) > 0 &&
  1301  		!oidInExtensions(oidExtensionCRLDistributionPoints, template.ExtraExtensions) {
  1302  		ret[n].Id = oidExtensionCRLDistributionPoints
  1303  
  1304  		var crlDp []distributionPoint
  1305  		for _, name := range template.CRLDistributionPoints {
  1306  			dp := distributionPoint{
  1307  				DistributionPoint: distributionPointName{
  1308  					FullName: []asn1.RawValue{
  1309  						{Tag: 6, Class: 2, Bytes: []byte(name)},
  1310  					},
  1311  				},
  1312  			}
  1313  			crlDp = append(crlDp, dp)
  1314  		}
  1315  
  1316  		ret[n].Value, err = asn1.Marshal(crlDp)
  1317  		if err != nil {
  1318  			return
  1319  		}
  1320  		n++
  1321  	}
  1322  
  1323  	// Adding another extension here? Remember to update the maximum number
  1324  	// of elements in the make() at the top of the function and the list of
  1325  	// template fields used in CreateCertificate documentation.
  1326  
  1327  	return append(ret[:n], template.ExtraExtensions...), nil
  1328  }
  1329  
  1330  func marshalKeyUsage(ku KeyUsage) (pkix.Extension, error) {
  1331  	ext := pkix.Extension{Id: oidExtensionKeyUsage, Critical: true}
  1332  
  1333  	var a [2]byte
  1334  	a[0] = reverseBitsInAByte(byte(ku))
  1335  	a[1] = reverseBitsInAByte(byte(ku >> 8))
  1336  
  1337  	l := 1
  1338  	if a[1] != 0 {
  1339  		l = 2
  1340  	}
  1341  
  1342  	bitString := a[:l]
  1343  	var err error
  1344  	ext.Value, err = asn1.Marshal(asn1.BitString{Bytes: bitString, BitLength: asn1BitLength(bitString)})
  1345  	return ext, err
  1346  }
  1347  
  1348  func marshalExtKeyUsage(extUsages []ExtKeyUsage, unknownUsages []asn1.ObjectIdentifier) (pkix.Extension, error) {
  1349  	ext := pkix.Extension{Id: oidExtensionExtendedKeyUsage}
  1350  
  1351  	oids := make([]asn1.ObjectIdentifier, len(extUsages)+len(unknownUsages))
  1352  	for i, u := range extUsages {
  1353  		if oid, ok := oidFromExtKeyUsage(u); ok {
  1354  			oids[i] = oid
  1355  		} else {
  1356  			return ext, errors.New("x509: unknown extended key usage")
  1357  		}
  1358  	}
  1359  
  1360  	copy(oids[len(extUsages):], unknownUsages)
  1361  
  1362  	var err error
  1363  	ext.Value, err = asn1.Marshal(oids)
  1364  	return ext, err
  1365  }
  1366  
  1367  func marshalBasicConstraints(isCA bool, maxPathLen int, maxPathLenZero bool) (pkix.Extension, error) {
  1368  	ext := pkix.Extension{Id: oidExtensionBasicConstraints, Critical: true}
  1369  	// Leaving MaxPathLen as zero indicates that no maximum path
  1370  	// length is desired, unless MaxPathLenZero is set. A value of
  1371  	// -1 causes encoding/asn1 to omit the value as desired.
  1372  	if maxPathLen == 0 && !maxPathLenZero {
  1373  		maxPathLen = -1
  1374  	}
  1375  	var err error
  1376  	ext.Value, err = asn1.Marshal(basicConstraints{isCA, maxPathLen})
  1377  	return ext, err
  1378  }
  1379  
  1380  func marshalCertificatePolicies(policies []OID, policyIdentifiers []asn1.ObjectIdentifier) (pkix.Extension, error) {
  1381  	ext := pkix.Extension{Id: oidExtensionCertificatePolicies}
  1382  
  1383  	b := cryptobyte.NewBuilder(make([]byte, 0, 128))
  1384  	b.AddASN1(cryptobyte_asn1.SEQUENCE, func(child *cryptobyte.Builder) {
  1385  		if usePoliciesField.Value() == "1" {
  1386  			usePoliciesField.IncNonDefault()
  1387  			for _, v := range policies {
  1388  				child.AddASN1(cryptobyte_asn1.SEQUENCE, func(child *cryptobyte.Builder) {
  1389  					child.AddASN1(cryptobyte_asn1.OBJECT_IDENTIFIER, func(child *cryptobyte.Builder) {
  1390  						if len(v.der) == 0 {
  1391  							child.SetError(errors.New("invalid policy object identifier"))
  1392  							return
  1393  						}
  1394  						child.AddBytes(v.der)
  1395  					})
  1396  				})
  1397  			}
  1398  		} else {
  1399  			for _, v := range policyIdentifiers {
  1400  				child.AddASN1(cryptobyte_asn1.SEQUENCE, func(child *cryptobyte.Builder) {
  1401  					child.AddASN1ObjectIdentifier(v)
  1402  				})
  1403  			}
  1404  		}
  1405  	})
  1406  
  1407  	var err error
  1408  	ext.Value, err = b.Bytes()
  1409  	return ext, err
  1410  }
  1411  
  1412  func buildCSRExtensions(template *CertificateRequest) ([]pkix.Extension, error) {
  1413  	var ret []pkix.Extension
  1414  
  1415  	if (len(template.DNSNames) > 0 || len(template.EmailAddresses) > 0 || len(template.IPAddresses) > 0 || len(template.URIs) > 0) &&
  1416  		!oidInExtensions(oidExtensionSubjectAltName, template.ExtraExtensions) {
  1417  		sanBytes, err := marshalSANs(template.DNSNames, template.EmailAddresses, template.IPAddresses, template.URIs)
  1418  		if err != nil {
  1419  			return nil, err
  1420  		}
  1421  
  1422  		ret = append(ret, pkix.Extension{
  1423  			Id:    oidExtensionSubjectAltName,
  1424  			Value: sanBytes,
  1425  		})
  1426  	}
  1427  
  1428  	return append(ret, template.ExtraExtensions...), nil
  1429  }
  1430  
  1431  func subjectBytes(cert *Certificate) ([]byte, error) {
  1432  	if len(cert.RawSubject) > 0 {
  1433  		return cert.RawSubject, nil
  1434  	}
  1435  
  1436  	return asn1.Marshal(cert.Subject.ToRDNSequence())
  1437  }
  1438  
  1439  // signingParamsForPublicKey returns the parameters to use for signing with
  1440  // priv. If requestedSigAlgo is not zero then it overrides the default
  1441  // signature algorithm.
  1442  func signingParamsForPublicKey(pub any, requestedSigAlgo SignatureAlgorithm) (hashFunc crypto.Hash, sigAlgo pkix.AlgorithmIdentifier, err error) {
  1443  	var pubType PublicKeyAlgorithm
  1444  
  1445  	switch pub := pub.(type) {
  1446  	case *rsa.PublicKey:
  1447  		pubType = RSA
  1448  		hashFunc = crypto.SHA256
  1449  		sigAlgo.Algorithm = oidSignatureSHA256WithRSA
  1450  		sigAlgo.Parameters = asn1.NullRawValue
  1451  
  1452  	case *ecdsa.PublicKey:
  1453  		pubType = ECDSA
  1454  
  1455  		switch pub.Curve {
  1456  		case elliptic.P224(), elliptic.P256():
  1457  			hashFunc = crypto.SHA256
  1458  			sigAlgo.Algorithm = oidSignatureECDSAWithSHA256
  1459  		case elliptic.P384():
  1460  			hashFunc = crypto.SHA384
  1461  			sigAlgo.Algorithm = oidSignatureECDSAWithSHA384
  1462  		case elliptic.P521():
  1463  			hashFunc = crypto.SHA512
  1464  			sigAlgo.Algorithm = oidSignatureECDSAWithSHA512
  1465  		default:
  1466  			err = errors.New("x509: unknown elliptic curve")
  1467  		}
  1468  
  1469  	case ed25519.PublicKey:
  1470  		pubType = Ed25519
  1471  		sigAlgo.Algorithm = oidSignatureEd25519
  1472  
  1473  	default:
  1474  		err = errors.New("x509: only RSA, ECDSA and Ed25519 keys supported")
  1475  	}
  1476  
  1477  	if err != nil {
  1478  		return
  1479  	}
  1480  
  1481  	if requestedSigAlgo == 0 {
  1482  		return
  1483  	}
  1484  
  1485  	found := false
  1486  	for _, details := range signatureAlgorithmDetails {
  1487  		if details.algo == requestedSigAlgo {
  1488  			if details.pubKeyAlgo != pubType {
  1489  				err = errors.New("x509: requested SignatureAlgorithm does not match private key type")
  1490  				return
  1491  			}
  1492  			sigAlgo.Algorithm, hashFunc = details.oid, details.hash
  1493  			if hashFunc == 0 && pubType != Ed25519 {
  1494  				err = errors.New("x509: cannot sign with hash function requested")
  1495  				return
  1496  			}
  1497  			if hashFunc == crypto.MD5 {
  1498  				err = errors.New("x509: signing with MD5 is not supported")
  1499  				return
  1500  			}
  1501  			if requestedSigAlgo.isRSAPSS() {
  1502  				sigAlgo.Parameters = hashToPSSParameters[hashFunc]
  1503  			}
  1504  			found = true
  1505  			break
  1506  		}
  1507  	}
  1508  
  1509  	if !found {
  1510  		err = errors.New("x509: unknown SignatureAlgorithm")
  1511  	}
  1512  
  1513  	return
  1514  }
  1515  
  1516  // emptyASN1Subject is the ASN.1 DER encoding of an empty Subject, which is
  1517  // just an empty SEQUENCE.
  1518  var emptyASN1Subject = []byte{0x30, 0}
  1519  
  1520  // CreateCertificate creates a new X.509 v3 certificate based on a template.
  1521  // The following members of template are currently used:
  1522  //
  1523  //   - AuthorityKeyId
  1524  //   - BasicConstraintsValid
  1525  //   - CRLDistributionPoints
  1526  //   - DNSNames
  1527  //   - EmailAddresses
  1528  //   - ExcludedDNSDomains
  1529  //   - ExcludedEmailAddresses
  1530  //   - ExcludedIPRanges
  1531  //   - ExcludedURIDomains
  1532  //   - ExtKeyUsage
  1533  //   - ExtraExtensions
  1534  //   - IPAddresses
  1535  //   - IsCA
  1536  //   - IssuingCertificateURL
  1537  //   - KeyUsage
  1538  //   - MaxPathLen
  1539  //   - MaxPathLenZero
  1540  //   - NotAfter
  1541  //   - NotBefore
  1542  //   - OCSPServer
  1543  //   - PermittedDNSDomains
  1544  //   - PermittedDNSDomainsCritical
  1545  //   - PermittedEmailAddresses
  1546  //   - PermittedIPRanges
  1547  //   - PermittedURIDomains
  1548  //   - PolicyIdentifiers (see note below)
  1549  //   - Policies (see note below)
  1550  //   - SerialNumber
  1551  //   - SignatureAlgorithm
  1552  //   - Subject
  1553  //   - SubjectKeyId
  1554  //   - URIs
  1555  //   - UnknownExtKeyUsage
  1556  //
  1557  // The certificate is signed by parent. If parent is equal to template then the
  1558  // certificate is self-signed. The parameter pub is the public key of the
  1559  // certificate to be generated and priv is the private key of the signer.
  1560  //
  1561  // The returned slice is the certificate in DER encoding.
  1562  //
  1563  // The currently supported key types are *rsa.PublicKey, *ecdsa.PublicKey and
  1564  // ed25519.PublicKey. pub must be a supported key type, and priv must be a
  1565  // crypto.Signer with a supported public key.
  1566  //
  1567  // The AuthorityKeyId will be taken from the SubjectKeyId of parent, if any,
  1568  // unless the resulting certificate is self-signed. Otherwise the value from
  1569  // template will be used.
  1570  //
  1571  // If SubjectKeyId from template is empty and the template is a CA, SubjectKeyId
  1572  // will be generated from the hash of the public key.
  1573  //
  1574  // The PolicyIdentifier and Policies fields are both used to marshal certificate
  1575  // policy OIDs. By default, only the PolicyIdentifier is marshaled, but if the
  1576  // GODEBUG setting "x509usepolicies" has the value "1", the Policies field will
  1577  // be marshalled instead of the PolicyIdentifier field. The Policies field can
  1578  // be used to marshal policy OIDs which have components that are larger than 31
  1579  // bits.
  1580  func CreateCertificate(rand io.Reader, template, parent *Certificate, pub, priv any) ([]byte, error) {
  1581  	key, ok := priv.(crypto.Signer)
  1582  	if !ok {
  1583  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  1584  	}
  1585  
  1586  	if template.SerialNumber == nil {
  1587  		return nil, errors.New("x509: no SerialNumber given")
  1588  	}
  1589  
  1590  	// RFC 5280 Section 4.1.2.2: serial number must positive
  1591  	//
  1592  	// We _should_ also restrict serials to <= 20 octets, but it turns out a lot of people
  1593  	// get this wrong, in part because the encoding can itself alter the length of the
  1594  	// serial. For now we accept these non-conformant serials.
  1595  	if template.SerialNumber.Sign() == -1 {
  1596  		return nil, errors.New("x509: serial number must be positive")
  1597  	}
  1598  
  1599  	if template.BasicConstraintsValid && !template.IsCA && template.MaxPathLen != -1 && (template.MaxPathLen != 0 || template.MaxPathLenZero) {
  1600  		return nil, errors.New("x509: only CAs are allowed to specify MaxPathLen")
  1601  	}
  1602  
  1603  	hashFunc, signatureAlgorithm, err := signingParamsForPublicKey(key.Public(), template.SignatureAlgorithm)
  1604  	if err != nil {
  1605  		return nil, err
  1606  	}
  1607  
  1608  	publicKeyBytes, publicKeyAlgorithm, err := marshalPublicKey(pub)
  1609  	if err != nil {
  1610  		return nil, err
  1611  	}
  1612  	if getPublicKeyAlgorithmFromOID(publicKeyAlgorithm.Algorithm) == UnknownPublicKeyAlgorithm {
  1613  		return nil, fmt.Errorf("x509: unsupported public key type: %T", pub)
  1614  	}
  1615  
  1616  	asn1Issuer, err := subjectBytes(parent)
  1617  	if err != nil {
  1618  		return nil, err
  1619  	}
  1620  
  1621  	asn1Subject, err := subjectBytes(template)
  1622  	if err != nil {
  1623  		return nil, err
  1624  	}
  1625  
  1626  	authorityKeyId := template.AuthorityKeyId
  1627  	if !bytes.Equal(asn1Issuer, asn1Subject) && len(parent.SubjectKeyId) > 0 {
  1628  		authorityKeyId = parent.SubjectKeyId
  1629  	}
  1630  
  1631  	subjectKeyId := template.SubjectKeyId
  1632  	if len(subjectKeyId) == 0 && template.IsCA {
  1633  		// SubjectKeyId generated using method 1 in RFC 5280, Section 4.2.1.2:
  1634  		//   (1) The keyIdentifier is composed of the 160-bit SHA-1 hash of the
  1635  		//   value of the BIT STRING subjectPublicKey (excluding the tag,
  1636  		//   length, and number of unused bits).
  1637  		h := sha1.Sum(publicKeyBytes)
  1638  		subjectKeyId = h[:]
  1639  	}
  1640  
  1641  	// Check that the signer's public key matches the private key, if available.
  1642  	type privateKey interface {
  1643  		Equal(crypto.PublicKey) bool
  1644  	}
  1645  	if privPub, ok := key.Public().(privateKey); !ok {
  1646  		return nil, errors.New("x509: internal error: supported public key does not implement Equal")
  1647  	} else if parent.PublicKey != nil && !privPub.Equal(parent.PublicKey) {
  1648  		return nil, errors.New("x509: provided PrivateKey doesn't match parent's PublicKey")
  1649  	}
  1650  
  1651  	extensions, err := buildCertExtensions(template, bytes.Equal(asn1Subject, emptyASN1Subject), authorityKeyId, subjectKeyId)
  1652  	if err != nil {
  1653  		return nil, err
  1654  	}
  1655  
  1656  	encodedPublicKey := asn1.BitString{BitLength: len(publicKeyBytes) * 8, Bytes: publicKeyBytes}
  1657  	c := tbsCertificate{
  1658  		Version:            2,
  1659  		SerialNumber:       template.SerialNumber,
  1660  		SignatureAlgorithm: signatureAlgorithm,
  1661  		Issuer:             asn1.RawValue{FullBytes: asn1Issuer},
  1662  		Validity:           validity{template.NotBefore.UTC(), template.NotAfter.UTC()},
  1663  		Subject:            asn1.RawValue{FullBytes: asn1Subject},
  1664  		PublicKey:          publicKeyInfo{nil, publicKeyAlgorithm, encodedPublicKey},
  1665  		Extensions:         extensions,
  1666  	}
  1667  
  1668  	tbsCertContents, err := asn1.Marshal(c)
  1669  	if err != nil {
  1670  		return nil, err
  1671  	}
  1672  	c.Raw = tbsCertContents
  1673  
  1674  	signed := tbsCertContents
  1675  	if hashFunc != 0 {
  1676  		h := hashFunc.New()
  1677  		h.Write(signed)
  1678  		signed = h.Sum(nil)
  1679  	}
  1680  
  1681  	var signerOpts crypto.SignerOpts = hashFunc
  1682  	if template.SignatureAlgorithm != 0 && template.SignatureAlgorithm.isRSAPSS() {
  1683  		signerOpts = &rsa.PSSOptions{
  1684  			SaltLength: rsa.PSSSaltLengthEqualsHash,
  1685  			Hash:       hashFunc,
  1686  		}
  1687  	}
  1688  
  1689  	var signature []byte
  1690  	signature, err = key.Sign(rand, signed, signerOpts)
  1691  	if err != nil {
  1692  		return nil, err
  1693  	}
  1694  
  1695  	signedCert, err := asn1.Marshal(certificate{
  1696  		c,
  1697  		signatureAlgorithm,
  1698  		asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  1699  	})
  1700  	if err != nil {
  1701  		return nil, err
  1702  	}
  1703  
  1704  	// Check the signature to ensure the crypto.Signer behaved correctly.
  1705  	if err := checkSignature(getSignatureAlgorithmFromAI(signatureAlgorithm), c.Raw, signature, key.Public(), true); err != nil {
  1706  		return nil, fmt.Errorf("x509: signature over certificate returned by signer is invalid: %w", err)
  1707  	}
  1708  
  1709  	return signedCert, nil
  1710  }
  1711  
  1712  // pemCRLPrefix is the magic string that indicates that we have a PEM encoded
  1713  // CRL.
  1714  var pemCRLPrefix = []byte("-----BEGIN X509 CRL")
  1715  
  1716  // pemType is the type of a PEM encoded CRL.
  1717  var pemType = "X509 CRL"
  1718  
  1719  // ParseCRL parses a CRL from the given bytes. It's often the case that PEM
  1720  // encoded CRLs will appear where they should be DER encoded, so this function
  1721  // will transparently handle PEM encoding as long as there isn't any leading
  1722  // garbage.
  1723  //
  1724  // Deprecated: Use [ParseRevocationList] instead.
  1725  func ParseCRL(crlBytes []byte) (*pkix.CertificateList, error) {
  1726  	if bytes.HasPrefix(crlBytes, pemCRLPrefix) {
  1727  		block, _ := pem.Decode(crlBytes)
  1728  		if block != nil && block.Type == pemType {
  1729  			crlBytes = block.Bytes
  1730  		}
  1731  	}
  1732  	return ParseDERCRL(crlBytes)
  1733  }
  1734  
  1735  // ParseDERCRL parses a DER encoded CRL from the given bytes.
  1736  //
  1737  // Deprecated: Use [ParseRevocationList] instead.
  1738  func ParseDERCRL(derBytes []byte) (*pkix.CertificateList, error) {
  1739  	certList := new(pkix.CertificateList)
  1740  	if rest, err := asn1.Unmarshal(derBytes, certList); err != nil {
  1741  		return nil, err
  1742  	} else if len(rest) != 0 {
  1743  		return nil, errors.New("x509: trailing data after CRL")
  1744  	}
  1745  	return certList, nil
  1746  }
  1747  
  1748  // CreateCRL returns a DER encoded CRL, signed by this Certificate, that
  1749  // contains the given list of revoked certificates.
  1750  //
  1751  // Deprecated: this method does not generate an RFC 5280 conformant X.509 v2 CRL.
  1752  // To generate a standards compliant CRL, use [CreateRevocationList] instead.
  1753  func (c *Certificate) CreateCRL(rand io.Reader, priv any, revokedCerts []pkix.RevokedCertificate, now, expiry time.Time) (crlBytes []byte, err error) {
  1754  	key, ok := priv.(crypto.Signer)
  1755  	if !ok {
  1756  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  1757  	}
  1758  
  1759  	hashFunc, signatureAlgorithm, err := signingParamsForPublicKey(key.Public(), 0)
  1760  	if err != nil {
  1761  		return nil, err
  1762  	}
  1763  
  1764  	// Force revocation times to UTC per RFC 5280.
  1765  	revokedCertsUTC := make([]pkix.RevokedCertificate, len(revokedCerts))
  1766  	for i, rc := range revokedCerts {
  1767  		rc.RevocationTime = rc.RevocationTime.UTC()
  1768  		revokedCertsUTC[i] = rc
  1769  	}
  1770  
  1771  	tbsCertList := pkix.TBSCertificateList{
  1772  		Version:             1,
  1773  		Signature:           signatureAlgorithm,
  1774  		Issuer:              c.Subject.ToRDNSequence(),
  1775  		ThisUpdate:          now.UTC(),
  1776  		NextUpdate:          expiry.UTC(),
  1777  		RevokedCertificates: revokedCertsUTC,
  1778  	}
  1779  
  1780  	// Authority Key Id
  1781  	if len(c.SubjectKeyId) > 0 {
  1782  		var aki pkix.Extension
  1783  		aki.Id = oidExtensionAuthorityKeyId
  1784  		aki.Value, err = asn1.Marshal(authKeyId{Id: c.SubjectKeyId})
  1785  		if err != nil {
  1786  			return
  1787  		}
  1788  		tbsCertList.Extensions = append(tbsCertList.Extensions, aki)
  1789  	}
  1790  
  1791  	tbsCertListContents, err := asn1.Marshal(tbsCertList)
  1792  	if err != nil {
  1793  		return
  1794  	}
  1795  
  1796  	signed := tbsCertListContents
  1797  	if hashFunc != 0 {
  1798  		h := hashFunc.New()
  1799  		h.Write(signed)
  1800  		signed = h.Sum(nil)
  1801  	}
  1802  
  1803  	var signature []byte
  1804  	signature, err = key.Sign(rand, signed, hashFunc)
  1805  	if err != nil {
  1806  		return
  1807  	}
  1808  
  1809  	return asn1.Marshal(pkix.CertificateList{
  1810  		TBSCertList:        tbsCertList,
  1811  		SignatureAlgorithm: signatureAlgorithm,
  1812  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  1813  	})
  1814  }
  1815  
  1816  // CertificateRequest represents a PKCS #10, certificate signature request.
  1817  type CertificateRequest struct {
  1818  	Raw                      []byte // Complete ASN.1 DER content (CSR, signature algorithm and signature).
  1819  	RawTBSCertificateRequest []byte // Certificate request info part of raw ASN.1 DER content.
  1820  	RawSubjectPublicKeyInfo  []byte // DER encoded SubjectPublicKeyInfo.
  1821  	RawSubject               []byte // DER encoded Subject.
  1822  
  1823  	Version            int
  1824  	Signature          []byte
  1825  	SignatureAlgorithm SignatureAlgorithm
  1826  
  1827  	PublicKeyAlgorithm PublicKeyAlgorithm
  1828  	PublicKey          any
  1829  
  1830  	Subject pkix.Name
  1831  
  1832  	// Attributes contains the CSR attributes that can parse as
  1833  	// pkix.AttributeTypeAndValueSET.
  1834  	//
  1835  	// Deprecated: Use Extensions and ExtraExtensions instead for parsing and
  1836  	// generating the requestedExtensions attribute.
  1837  	Attributes []pkix.AttributeTypeAndValueSET
  1838  
  1839  	// Extensions contains all requested extensions, in raw form. When parsing
  1840  	// CSRs, this can be used to extract extensions that are not parsed by this
  1841  	// package.
  1842  	Extensions []pkix.Extension
  1843  
  1844  	// ExtraExtensions contains extensions to be copied, raw, into any CSR
  1845  	// marshaled by CreateCertificateRequest. Values override any extensions
  1846  	// that would otherwise be produced based on the other fields but are
  1847  	// overridden by any extensions specified in Attributes.
  1848  	//
  1849  	// The ExtraExtensions field is not populated by ParseCertificateRequest,
  1850  	// see Extensions instead.
  1851  	ExtraExtensions []pkix.Extension
  1852  
  1853  	// Subject Alternate Name values.
  1854  	DNSNames       []string
  1855  	EmailAddresses []string
  1856  	IPAddresses    []net.IP
  1857  	URIs           []*url.URL
  1858  }
  1859  
  1860  // These structures reflect the ASN.1 structure of X.509 certificate
  1861  // signature requests (see RFC 2986):
  1862  
  1863  type tbsCertificateRequest struct {
  1864  	Raw           asn1.RawContent
  1865  	Version       int
  1866  	Subject       asn1.RawValue
  1867  	PublicKey     publicKeyInfo
  1868  	RawAttributes []asn1.RawValue `asn1:"tag:0"`
  1869  }
  1870  
  1871  type certificateRequest struct {
  1872  	Raw                asn1.RawContent
  1873  	TBSCSR             tbsCertificateRequest
  1874  	SignatureAlgorithm pkix.AlgorithmIdentifier
  1875  	SignatureValue     asn1.BitString
  1876  }
  1877  
  1878  // oidExtensionRequest is a PKCS #9 OBJECT IDENTIFIER that indicates requested
  1879  // extensions in a CSR.
  1880  var oidExtensionRequest = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 14}
  1881  
  1882  // newRawAttributes converts AttributeTypeAndValueSETs from a template
  1883  // CertificateRequest's Attributes into tbsCertificateRequest RawAttributes.
  1884  func newRawAttributes(attributes []pkix.AttributeTypeAndValueSET) ([]asn1.RawValue, error) {
  1885  	var rawAttributes []asn1.RawValue
  1886  	b, err := asn1.Marshal(attributes)
  1887  	if err != nil {
  1888  		return nil, err
  1889  	}
  1890  	rest, err := asn1.Unmarshal(b, &rawAttributes)
  1891  	if err != nil {
  1892  		return nil, err
  1893  	}
  1894  	if len(rest) != 0 {
  1895  		return nil, errors.New("x509: failed to unmarshal raw CSR Attributes")
  1896  	}
  1897  	return rawAttributes, nil
  1898  }
  1899  
  1900  // parseRawAttributes Unmarshals RawAttributes into AttributeTypeAndValueSETs.
  1901  func parseRawAttributes(rawAttributes []asn1.RawValue) []pkix.AttributeTypeAndValueSET {
  1902  	var attributes []pkix.AttributeTypeAndValueSET
  1903  	for _, rawAttr := range rawAttributes {
  1904  		var attr pkix.AttributeTypeAndValueSET
  1905  		rest, err := asn1.Unmarshal(rawAttr.FullBytes, &attr)
  1906  		// Ignore attributes that don't parse into pkix.AttributeTypeAndValueSET
  1907  		// (i.e.: challengePassword or unstructuredName).
  1908  		if err == nil && len(rest) == 0 {
  1909  			attributes = append(attributes, attr)
  1910  		}
  1911  	}
  1912  	return attributes
  1913  }
  1914  
  1915  // parseCSRExtensions parses the attributes from a CSR and extracts any
  1916  // requested extensions.
  1917  func parseCSRExtensions(rawAttributes []asn1.RawValue) ([]pkix.Extension, error) {
  1918  	// pkcs10Attribute reflects the Attribute structure from RFC 2986, Section 4.1.
  1919  	type pkcs10Attribute struct {
  1920  		Id     asn1.ObjectIdentifier
  1921  		Values []asn1.RawValue `asn1:"set"`
  1922  	}
  1923  
  1924  	var ret []pkix.Extension
  1925  	requestedExts := make(map[string]bool)
  1926  	for _, rawAttr := range rawAttributes {
  1927  		var attr pkcs10Attribute
  1928  		if rest, err := asn1.Unmarshal(rawAttr.FullBytes, &attr); err != nil || len(rest) != 0 || len(attr.Values) == 0 {
  1929  			// Ignore attributes that don't parse.
  1930  			continue
  1931  		}
  1932  
  1933  		if !attr.Id.Equal(oidExtensionRequest) {
  1934  			continue
  1935  		}
  1936  
  1937  		var extensions []pkix.Extension
  1938  		if _, err := asn1.Unmarshal(attr.Values[0].FullBytes, &extensions); err != nil {
  1939  			return nil, err
  1940  		}
  1941  		for _, ext := range extensions {
  1942  			oidStr := ext.Id.String()
  1943  			if requestedExts[oidStr] {
  1944  				return nil, errors.New("x509: certificate request contains duplicate requested extensions")
  1945  			}
  1946  			requestedExts[oidStr] = true
  1947  		}
  1948  		ret = append(ret, extensions...)
  1949  	}
  1950  
  1951  	return ret, nil
  1952  }
  1953  
  1954  // CreateCertificateRequest creates a new certificate request based on a
  1955  // template. The following members of template are used:
  1956  //
  1957  //   - SignatureAlgorithm
  1958  //   - Subject
  1959  //   - DNSNames
  1960  //   - EmailAddresses
  1961  //   - IPAddresses
  1962  //   - URIs
  1963  //   - ExtraExtensions
  1964  //   - Attributes (deprecated)
  1965  //
  1966  // priv is the private key to sign the CSR with, and the corresponding public
  1967  // key will be included in the CSR. It must implement crypto.Signer and its
  1968  // Public() method must return a *rsa.PublicKey or a *ecdsa.PublicKey or a
  1969  // ed25519.PublicKey. (A *rsa.PrivateKey, *ecdsa.PrivateKey or
  1970  // ed25519.PrivateKey satisfies this.)
  1971  //
  1972  // The returned slice is the certificate request in DER encoding.
  1973  func CreateCertificateRequest(rand io.Reader, template *CertificateRequest, priv any) (csr []byte, err error) {
  1974  	key, ok := priv.(crypto.Signer)
  1975  	if !ok {
  1976  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  1977  	}
  1978  
  1979  	var hashFunc crypto.Hash
  1980  	var sigAlgo pkix.AlgorithmIdentifier
  1981  	hashFunc, sigAlgo, err = signingParamsForPublicKey(key.Public(), template.SignatureAlgorithm)
  1982  	if err != nil {
  1983  		return nil, err
  1984  	}
  1985  
  1986  	var publicKeyBytes []byte
  1987  	var publicKeyAlgorithm pkix.AlgorithmIdentifier
  1988  	publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(key.Public())
  1989  	if err != nil {
  1990  		return nil, err
  1991  	}
  1992  
  1993  	extensions, err := buildCSRExtensions(template)
  1994  	if err != nil {
  1995  		return nil, err
  1996  	}
  1997  
  1998  	// Make a copy of template.Attributes because we may alter it below.
  1999  	attributes := make([]pkix.AttributeTypeAndValueSET, 0, len(template.Attributes))
  2000  	for _, attr := range template.Attributes {
  2001  		values := make([][]pkix.AttributeTypeAndValue, len(attr.Value))
  2002  		copy(values, attr.Value)
  2003  		attributes = append(attributes, pkix.AttributeTypeAndValueSET{
  2004  			Type:  attr.Type,
  2005  			Value: values,
  2006  		})
  2007  	}
  2008  
  2009  	extensionsAppended := false
  2010  	if len(extensions) > 0 {
  2011  		// Append the extensions to an existing attribute if possible.
  2012  		for _, atvSet := range attributes {
  2013  			if !atvSet.Type.Equal(oidExtensionRequest) || len(atvSet.Value) == 0 {
  2014  				continue
  2015  			}
  2016  
  2017  			// specifiedExtensions contains all the extensions that we
  2018  			// found specified via template.Attributes.
  2019  			specifiedExtensions := make(map[string]bool)
  2020  
  2021  			for _, atvs := range atvSet.Value {
  2022  				for _, atv := range atvs {
  2023  					specifiedExtensions[atv.Type.String()] = true
  2024  				}
  2025  			}
  2026  
  2027  			newValue := make([]pkix.AttributeTypeAndValue, 0, len(atvSet.Value[0])+len(extensions))
  2028  			newValue = append(newValue, atvSet.Value[0]...)
  2029  
  2030  			for _, e := range extensions {
  2031  				if specifiedExtensions[e.Id.String()] {
  2032  					// Attributes already contained a value for
  2033  					// this extension and it takes priority.
  2034  					continue
  2035  				}
  2036  
  2037  				newValue = append(newValue, pkix.AttributeTypeAndValue{
  2038  					// There is no place for the critical
  2039  					// flag in an AttributeTypeAndValue.
  2040  					Type:  e.Id,
  2041  					Value: e.Value,
  2042  				})
  2043  			}
  2044  
  2045  			atvSet.Value[0] = newValue
  2046  			extensionsAppended = true
  2047  			break
  2048  		}
  2049  	}
  2050  
  2051  	rawAttributes, err := newRawAttributes(attributes)
  2052  	if err != nil {
  2053  		return
  2054  	}
  2055  
  2056  	// If not included in attributes, add a new attribute for the
  2057  	// extensions.
  2058  	if len(extensions) > 0 && !extensionsAppended {
  2059  		attr := struct {
  2060  			Type  asn1.ObjectIdentifier
  2061  			Value [][]pkix.Extension `asn1:"set"`
  2062  		}{
  2063  			Type:  oidExtensionRequest,
  2064  			Value: [][]pkix.Extension{extensions},
  2065  		}
  2066  
  2067  		b, err := asn1.Marshal(attr)
  2068  		if err != nil {
  2069  			return nil, errors.New("x509: failed to serialise extensions attribute: " + err.Error())
  2070  		}
  2071  
  2072  		var rawValue asn1.RawValue
  2073  		if _, err := asn1.Unmarshal(b, &rawValue); err != nil {
  2074  			return nil, err
  2075  		}
  2076  
  2077  		rawAttributes = append(rawAttributes, rawValue)
  2078  	}
  2079  
  2080  	asn1Subject := template.RawSubject
  2081  	if len(asn1Subject) == 0 {
  2082  		asn1Subject, err = asn1.Marshal(template.Subject.ToRDNSequence())
  2083  		if err != nil {
  2084  			return nil, err
  2085  		}
  2086  	}
  2087  
  2088  	tbsCSR := tbsCertificateRequest{
  2089  		Version: 0, // PKCS #10, RFC 2986
  2090  		Subject: asn1.RawValue{FullBytes: asn1Subject},
  2091  		PublicKey: publicKeyInfo{
  2092  			Algorithm: publicKeyAlgorithm,
  2093  			PublicKey: asn1.BitString{
  2094  				Bytes:     publicKeyBytes,
  2095  				BitLength: len(publicKeyBytes) * 8,
  2096  			},
  2097  		},
  2098  		RawAttributes: rawAttributes,
  2099  	}
  2100  
  2101  	tbsCSRContents, err := asn1.Marshal(tbsCSR)
  2102  	if err != nil {
  2103  		return
  2104  	}
  2105  	tbsCSR.Raw = tbsCSRContents
  2106  
  2107  	signed := tbsCSRContents
  2108  	if hashFunc != 0 {
  2109  		h := hashFunc.New()
  2110  		h.Write(signed)
  2111  		signed = h.Sum(nil)
  2112  	}
  2113  
  2114  	var signature []byte
  2115  	signature, err = key.Sign(rand, signed, hashFunc)
  2116  	if err != nil {
  2117  		return
  2118  	}
  2119  
  2120  	return asn1.Marshal(certificateRequest{
  2121  		TBSCSR:             tbsCSR,
  2122  		SignatureAlgorithm: sigAlgo,
  2123  		SignatureValue: asn1.BitString{
  2124  			Bytes:     signature,
  2125  			BitLength: len(signature) * 8,
  2126  		},
  2127  	})
  2128  }
  2129  
  2130  // ParseCertificateRequest parses a single certificate request from the
  2131  // given ASN.1 DER data.
  2132  func ParseCertificateRequest(asn1Data []byte) (*CertificateRequest, error) {
  2133  	var csr certificateRequest
  2134  
  2135  	rest, err := asn1.Unmarshal(asn1Data, &csr)
  2136  	if err != nil {
  2137  		return nil, err
  2138  	} else if len(rest) != 0 {
  2139  		return nil, asn1.SyntaxError{Msg: "trailing data"}
  2140  	}
  2141  
  2142  	return parseCertificateRequest(&csr)
  2143  }
  2144  
  2145  func parseCertificateRequest(in *certificateRequest) (*CertificateRequest, error) {
  2146  	out := &CertificateRequest{
  2147  		Raw:                      in.Raw,
  2148  		RawTBSCertificateRequest: in.TBSCSR.Raw,
  2149  		RawSubjectPublicKeyInfo:  in.TBSCSR.PublicKey.Raw,
  2150  		RawSubject:               in.TBSCSR.Subject.FullBytes,
  2151  
  2152  		Signature:          in.SignatureValue.RightAlign(),
  2153  		SignatureAlgorithm: getSignatureAlgorithmFromAI(in.SignatureAlgorithm),
  2154  
  2155  		PublicKeyAlgorithm: getPublicKeyAlgorithmFromOID(in.TBSCSR.PublicKey.Algorithm.Algorithm),
  2156  
  2157  		Version:    in.TBSCSR.Version,
  2158  		Attributes: parseRawAttributes(in.TBSCSR.RawAttributes),
  2159  	}
  2160  
  2161  	var err error
  2162  	if out.PublicKeyAlgorithm != UnknownPublicKeyAlgorithm {
  2163  		out.PublicKey, err = parsePublicKey(&in.TBSCSR.PublicKey)
  2164  		if err != nil {
  2165  			return nil, err
  2166  		}
  2167  	}
  2168  
  2169  	var subject pkix.RDNSequence
  2170  	if rest, err := asn1.Unmarshal(in.TBSCSR.Subject.FullBytes, &subject); err != nil {
  2171  		return nil, err
  2172  	} else if len(rest) != 0 {
  2173  		return nil, errors.New("x509: trailing data after X.509 Subject")
  2174  	}
  2175  
  2176  	out.Subject.FillFromRDNSequence(&subject)
  2177  
  2178  	if out.Extensions, err = parseCSRExtensions(in.TBSCSR.RawAttributes); err != nil {
  2179  		return nil, err
  2180  	}
  2181  
  2182  	for _, extension := range out.Extensions {
  2183  		switch {
  2184  		case extension.Id.Equal(oidExtensionSubjectAltName):
  2185  			out.DNSNames, out.EmailAddresses, out.IPAddresses, out.URIs, err = parseSANExtension(extension.Value)
  2186  			if err != nil {
  2187  				return nil, err
  2188  			}
  2189  		}
  2190  	}
  2191  
  2192  	return out, nil
  2193  }
  2194  
  2195  // CheckSignature reports whether the signature on c is valid.
  2196  func (c *CertificateRequest) CheckSignature() error {
  2197  	return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificateRequest, c.Signature, c.PublicKey, true)
  2198  }
  2199  
  2200  // RevocationListEntry represents an entry in the revokedCertificates
  2201  // sequence of a CRL.
  2202  type RevocationListEntry struct {
  2203  	// Raw contains the raw bytes of the revokedCertificates entry. It is set when
  2204  	// parsing a CRL; it is ignored when generating a CRL.
  2205  	Raw []byte
  2206  
  2207  	// SerialNumber represents the serial number of a revoked certificate. It is
  2208  	// both used when creating a CRL and populated when parsing a CRL. It must not
  2209  	// be nil.
  2210  	SerialNumber *big.Int
  2211  	// RevocationTime represents the time at which the certificate was revoked. It
  2212  	// is both used when creating a CRL and populated when parsing a CRL. It must
  2213  	// not be the zero time.
  2214  	RevocationTime time.Time
  2215  	// ReasonCode represents the reason for revocation, using the integer enum
  2216  	// values specified in RFC 5280 Section 5.3.1. When creating a CRL, the zero
  2217  	// value will result in the reasonCode extension being omitted. When parsing a
  2218  	// CRL, the zero value may represent either the reasonCode extension being
  2219  	// absent (which implies the default revocation reason of 0/Unspecified), or
  2220  	// it may represent the reasonCode extension being present and explicitly
  2221  	// containing a value of 0/Unspecified (which should not happen according to
  2222  	// the DER encoding rules, but can and does happen anyway).
  2223  	ReasonCode int
  2224  
  2225  	// Extensions contains raw X.509 extensions. When parsing CRL entries,
  2226  	// this can be used to extract non-critical extensions that are not
  2227  	// parsed by this package. When marshaling CRL entries, the Extensions
  2228  	// field is ignored, see ExtraExtensions.
  2229  	Extensions []pkix.Extension
  2230  	// ExtraExtensions contains extensions to be copied, raw, into any
  2231  	// marshaled CRL entries. Values override any extensions that would
  2232  	// otherwise be produced based on the other fields. The ExtraExtensions
  2233  	// field is not populated when parsing CRL entries, see Extensions.
  2234  	ExtraExtensions []pkix.Extension
  2235  }
  2236  
  2237  // RevocationList represents a [Certificate] Revocation List (CRL) as specified
  2238  // by RFC 5280.
  2239  type RevocationList struct {
  2240  	// Raw contains the complete ASN.1 DER content of the CRL (tbsCertList,
  2241  	// signatureAlgorithm, and signatureValue.)
  2242  	Raw []byte
  2243  	// RawTBSRevocationList contains just the tbsCertList portion of the ASN.1
  2244  	// DER.
  2245  	RawTBSRevocationList []byte
  2246  	// RawIssuer contains the DER encoded Issuer.
  2247  	RawIssuer []byte
  2248  
  2249  	// Issuer contains the DN of the issuing certificate.
  2250  	Issuer pkix.Name
  2251  	// AuthorityKeyId is used to identify the public key associated with the
  2252  	// issuing certificate. It is populated from the authorityKeyIdentifier
  2253  	// extension when parsing a CRL. It is ignored when creating a CRL; the
  2254  	// extension is populated from the issuing certificate itself.
  2255  	AuthorityKeyId []byte
  2256  
  2257  	Signature []byte
  2258  	// SignatureAlgorithm is used to determine the signature algorithm to be
  2259  	// used when signing the CRL. If 0 the default algorithm for the signing
  2260  	// key will be used.
  2261  	SignatureAlgorithm SignatureAlgorithm
  2262  
  2263  	// RevokedCertificateEntries represents the revokedCertificates sequence in
  2264  	// the CRL. It is used when creating a CRL and also populated when parsing a
  2265  	// CRL. When creating a CRL, it may be empty or nil, in which case the
  2266  	// revokedCertificates ASN.1 sequence will be omitted from the CRL entirely.
  2267  	RevokedCertificateEntries []RevocationListEntry
  2268  
  2269  	// RevokedCertificates is used to populate the revokedCertificates
  2270  	// sequence in the CRL if RevokedCertificateEntries is empty. It may be empty
  2271  	// or nil, in which case an empty CRL will be created.
  2272  	//
  2273  	// Deprecated: Use RevokedCertificateEntries instead.
  2274  	RevokedCertificates []pkix.RevokedCertificate
  2275  
  2276  	// Number is used to populate the X.509 v2 cRLNumber extension in the CRL,
  2277  	// which should be a monotonically increasing sequence number for a given
  2278  	// CRL scope and CRL issuer. It is also populated from the cRLNumber
  2279  	// extension when parsing a CRL.
  2280  	Number *big.Int
  2281  
  2282  	// ThisUpdate is used to populate the thisUpdate field in the CRL, which
  2283  	// indicates the issuance date of the CRL.
  2284  	ThisUpdate time.Time
  2285  	// NextUpdate is used to populate the nextUpdate field in the CRL, which
  2286  	// indicates the date by which the next CRL will be issued. NextUpdate
  2287  	// must be greater than ThisUpdate.
  2288  	NextUpdate time.Time
  2289  
  2290  	// Extensions contains raw X.509 extensions. When creating a CRL,
  2291  	// the Extensions field is ignored, see ExtraExtensions.
  2292  	Extensions []pkix.Extension
  2293  
  2294  	// ExtraExtensions contains any additional extensions to add directly to
  2295  	// the CRL.
  2296  	ExtraExtensions []pkix.Extension
  2297  }
  2298  
  2299  // These structures reflect the ASN.1 structure of X.509 CRLs better than
  2300  // the existing crypto/x509/pkix variants do. These mirror the existing
  2301  // certificate structs in this file.
  2302  //
  2303  // Notably, we include issuer as an asn1.RawValue, mirroring the behavior of
  2304  // tbsCertificate and allowing raw (unparsed) subjects to be passed cleanly.
  2305  type certificateList struct {
  2306  	TBSCertList        tbsCertificateList
  2307  	SignatureAlgorithm pkix.AlgorithmIdentifier
  2308  	SignatureValue     asn1.BitString
  2309  }
  2310  
  2311  type tbsCertificateList struct {
  2312  	Raw                 asn1.RawContent
  2313  	Version             int `asn1:"optional,default:0"`
  2314  	Signature           pkix.AlgorithmIdentifier
  2315  	Issuer              asn1.RawValue
  2316  	ThisUpdate          time.Time
  2317  	NextUpdate          time.Time                 `asn1:"optional"`
  2318  	RevokedCertificates []pkix.RevokedCertificate `asn1:"optional"`
  2319  	Extensions          []pkix.Extension          `asn1:"tag:0,optional,explicit"`
  2320  }
  2321  
  2322  // CreateRevocationList creates a new X.509 v2 [Certificate] Revocation List,
  2323  // according to RFC 5280, based on template.
  2324  //
  2325  // The CRL is signed by priv which should be the private key associated with
  2326  // the public key in the issuer certificate.
  2327  //
  2328  // The issuer may not be nil, and the crlSign bit must be set in [KeyUsage] in
  2329  // order to use it as a CRL issuer.
  2330  //
  2331  // The issuer distinguished name CRL field and authority key identifier
  2332  // extension are populated using the issuer certificate. issuer must have
  2333  // SubjectKeyId set.
  2334  func CreateRevocationList(rand io.Reader, template *RevocationList, issuer *Certificate, priv crypto.Signer) ([]byte, error) {
  2335  	if template == nil {
  2336  		return nil, errors.New("x509: template can not be nil")
  2337  	}
  2338  	if issuer == nil {
  2339  		return nil, errors.New("x509: issuer can not be nil")
  2340  	}
  2341  	if (issuer.KeyUsage & KeyUsageCRLSign) == 0 {
  2342  		return nil, errors.New("x509: issuer must have the crlSign key usage bit set")
  2343  	}
  2344  	if len(issuer.SubjectKeyId) == 0 {
  2345  		return nil, errors.New("x509: issuer certificate doesn't contain a subject key identifier")
  2346  	}
  2347  	if template.NextUpdate.Before(template.ThisUpdate) {
  2348  		return nil, errors.New("x509: template.ThisUpdate is after template.NextUpdate")
  2349  	}
  2350  	if template.Number == nil {
  2351  		return nil, errors.New("x509: template contains nil Number field")
  2352  	}
  2353  
  2354  	hashFunc, signatureAlgorithm, err := signingParamsForPublicKey(priv.Public(), template.SignatureAlgorithm)
  2355  	if err != nil {
  2356  		return nil, err
  2357  	}
  2358  
  2359  	var revokedCerts []pkix.RevokedCertificate
  2360  	// Only process the deprecated RevokedCertificates field if it is populated
  2361  	// and the new RevokedCertificateEntries field is not populated.
  2362  	if len(template.RevokedCertificates) > 0 && len(template.RevokedCertificateEntries) == 0 {
  2363  		// Force revocation times to UTC per RFC 5280.
  2364  		revokedCerts = make([]pkix.RevokedCertificate, len(template.RevokedCertificates))
  2365  		for i, rc := range template.RevokedCertificates {
  2366  			rc.RevocationTime = rc.RevocationTime.UTC()
  2367  			revokedCerts[i] = rc
  2368  		}
  2369  	} else {
  2370  		// Convert the ReasonCode field to a proper extension, and force revocation
  2371  		// times to UTC per RFC 5280.
  2372  		revokedCerts = make([]pkix.RevokedCertificate, len(template.RevokedCertificateEntries))
  2373  		for i, rce := range template.RevokedCertificateEntries {
  2374  			if rce.SerialNumber == nil {
  2375  				return nil, errors.New("x509: template contains entry with nil SerialNumber field")
  2376  			}
  2377  			if rce.RevocationTime.IsZero() {
  2378  				return nil, errors.New("x509: template contains entry with zero RevocationTime field")
  2379  			}
  2380  
  2381  			rc := pkix.RevokedCertificate{
  2382  				SerialNumber:   rce.SerialNumber,
  2383  				RevocationTime: rce.RevocationTime.UTC(),
  2384  			}
  2385  
  2386  			// Copy over any extra extensions, except for a Reason Code extension,
  2387  			// because we'll synthesize that ourselves to ensure it is correct.
  2388  			exts := make([]pkix.Extension, 0, len(rce.ExtraExtensions))
  2389  			for _, ext := range rce.ExtraExtensions {
  2390  				if ext.Id.Equal(oidExtensionReasonCode) {
  2391  					return nil, errors.New("x509: template contains entry with ReasonCode ExtraExtension; use ReasonCode field instead")
  2392  				}
  2393  				exts = append(exts, ext)
  2394  			}
  2395  
  2396  			// Only add a reasonCode extension if the reason is non-zero, as per
  2397  			// RFC 5280 Section 5.3.1.
  2398  			if rce.ReasonCode != 0 {
  2399  				reasonBytes, err := asn1.Marshal(asn1.Enumerated(rce.ReasonCode))
  2400  				if err != nil {
  2401  					return nil, err
  2402  				}
  2403  
  2404  				exts = append(exts, pkix.Extension{
  2405  					Id:    oidExtensionReasonCode,
  2406  					Value: reasonBytes,
  2407  				})
  2408  			}
  2409  
  2410  			if len(exts) > 0 {
  2411  				rc.Extensions = exts
  2412  			}
  2413  			revokedCerts[i] = rc
  2414  		}
  2415  	}
  2416  
  2417  	aki, err := asn1.Marshal(authKeyId{Id: issuer.SubjectKeyId})
  2418  	if err != nil {
  2419  		return nil, err
  2420  	}
  2421  
  2422  	if numBytes := template.Number.Bytes(); len(numBytes) > 20 || (len(numBytes) == 20 && numBytes[0]&0x80 != 0) {
  2423  		return nil, errors.New("x509: CRL number exceeds 20 octets")
  2424  	}
  2425  	crlNum, err := asn1.Marshal(template.Number)
  2426  	if err != nil {
  2427  		return nil, err
  2428  	}
  2429  
  2430  	// Correctly use the issuer's subject sequence if one is specified.
  2431  	issuerSubject, err := subjectBytes(issuer)
  2432  	if err != nil {
  2433  		return nil, err
  2434  	}
  2435  
  2436  	tbsCertList := tbsCertificateList{
  2437  		Version:    1, // v2
  2438  		Signature:  signatureAlgorithm,
  2439  		Issuer:     asn1.RawValue{FullBytes: issuerSubject},
  2440  		ThisUpdate: template.ThisUpdate.UTC(),
  2441  		NextUpdate: template.NextUpdate.UTC(),
  2442  		Extensions: []pkix.Extension{
  2443  			{
  2444  				Id:    oidExtensionAuthorityKeyId,
  2445  				Value: aki,
  2446  			},
  2447  			{
  2448  				Id:    oidExtensionCRLNumber,
  2449  				Value: crlNum,
  2450  			},
  2451  		},
  2452  	}
  2453  	if len(revokedCerts) > 0 {
  2454  		tbsCertList.RevokedCertificates = revokedCerts
  2455  	}
  2456  
  2457  	if len(template.ExtraExtensions) > 0 {
  2458  		tbsCertList.Extensions = append(tbsCertList.Extensions, template.ExtraExtensions...)
  2459  	}
  2460  
  2461  	tbsCertListContents, err := asn1.Marshal(tbsCertList)
  2462  	if err != nil {
  2463  		return nil, err
  2464  	}
  2465  
  2466  	// Optimization to only marshal this struct once, when signing and
  2467  	// then embedding in certificateList below.
  2468  	tbsCertList.Raw = tbsCertListContents
  2469  
  2470  	input := tbsCertListContents
  2471  	if hashFunc != 0 {
  2472  		h := hashFunc.New()
  2473  		h.Write(tbsCertListContents)
  2474  		input = h.Sum(nil)
  2475  	}
  2476  	var signerOpts crypto.SignerOpts = hashFunc
  2477  	if template.SignatureAlgorithm.isRSAPSS() {
  2478  		signerOpts = &rsa.PSSOptions{
  2479  			SaltLength: rsa.PSSSaltLengthEqualsHash,
  2480  			Hash:       hashFunc,
  2481  		}
  2482  	}
  2483  
  2484  	signature, err := priv.Sign(rand, input, signerOpts)
  2485  	if err != nil {
  2486  		return nil, err
  2487  	}
  2488  
  2489  	return asn1.Marshal(certificateList{
  2490  		TBSCertList:        tbsCertList,
  2491  		SignatureAlgorithm: signatureAlgorithm,
  2492  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  2493  	})
  2494  }
  2495  
  2496  // CheckSignatureFrom verifies that the signature on rl is a valid signature
  2497  // from issuer.
  2498  func (rl *RevocationList) CheckSignatureFrom(parent *Certificate) error {
  2499  	if parent.Version == 3 && !parent.BasicConstraintsValid ||
  2500  		parent.BasicConstraintsValid && !parent.IsCA {
  2501  		return ConstraintViolationError{}
  2502  	}
  2503  
  2504  	if parent.KeyUsage != 0 && parent.KeyUsage&KeyUsageCRLSign == 0 {
  2505  		return ConstraintViolationError{}
  2506  	}
  2507  
  2508  	if parent.PublicKeyAlgorithm == UnknownPublicKeyAlgorithm {
  2509  		return ErrUnsupportedAlgorithm
  2510  	}
  2511  
  2512  	return parent.CheckSignature(rl.SignatureAlgorithm, rl.RawTBSRevocationList, rl.Signature)
  2513  }
  2514  

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