cipher_asm.go

Documentation: crypto/aes

     1  // Copyright 2012 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  //go:build amd64 || arm64 || ppc64 || ppc64le
     6  
     7  package aes
     8  
     9  import (
    10  	"crypto/cipher"
    11  	"crypto/internal/alias"
    12  	"crypto/internal/boring"
    13  	"internal/cpu"
    14  	"internal/goarch"
    15  )
    16  
    17  // defined in asm_*.s
    18  
    19  //go:noescape
    20  func encryptBlockAsm(nr int, xk *uint32, dst, src *byte)
    21  
    22  //go:noescape
    23  func decryptBlockAsm(nr int, xk *uint32, dst, src *byte)
    24  
    25  //go:noescape
    26  func expandKeyAsm(nr int, key *byte, enc *uint32, dec *uint32)
    27  
    28  type aesCipherAsm struct {
    29  	aesCipher
    30  }
    31  
    32  // aesCipherGCM implements crypto/cipher.gcmAble so that crypto/cipher.NewGCM
    33  // will use the optimised implementation in aes_gcm.go when possible.
    34  // Instances of this type only exist when hasGCMAsm returns true. Likewise,
    35  // the gcmAble implementation is in aes_gcm.go.
    36  type aesCipherGCM struct {
    37  	aesCipherAsm
    38  }
    39  
    40  var supportsAES = cpu.X86.HasAES || cpu.ARM64.HasAES || goarch.IsPpc64 == 1 || goarch.IsPpc64le == 1
    41  var supportsGFMUL = cpu.X86.HasPCLMULQDQ || cpu.ARM64.HasPMULL
    42  
    43  func newCipher(key []byte) (cipher.Block, error) {
    44  	if !supportsAES {
    45  		return newCipherGeneric(key)
    46  	}
    47  	n := len(key) + 28
    48  	c := aesCipherAsm{aesCipher{make([]uint32, n), make([]uint32, n)}}
    49  	var rounds int
    50  	switch len(key) {
    51  	case 128 / 8:
    52  		rounds = 10
    53  	case 192 / 8:
    54  		rounds = 12
    55  	case 256 / 8:
    56  		rounds = 14
    57  	default:
    58  		return nil, KeySizeError(len(key))
    59  	}
    60  
    61  	expandKeyAsm(rounds, &key[0], &c.enc[0], &c.dec[0])
    62  	if supportsAES && supportsGFMUL {
    63  		return &aesCipherGCM{c}, nil
    64  	}
    65  	return &c, nil
    66  }
    67  
    68  func (c *aesCipherAsm) BlockSize() int { return BlockSize }
    69  
    70  func (c *aesCipherAsm) Encrypt(dst, src []byte) {
    71  	boring.Unreachable()
    72  	if len(src) < BlockSize {
    73  		panic("crypto/aes: input not full block")
    74  	}
    75  	if len(dst) < BlockSize {
    76  		panic("crypto/aes: output not full block")
    77  	}
    78  	if alias.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
    79  		panic("crypto/aes: invalid buffer overlap")
    80  	}
    81  	encryptBlockAsm(len(c.enc)/4-1, &c.enc[0], &dst[0], &src[0])
    82  }
    83  
    84  func (c *aesCipherAsm) Decrypt(dst, src []byte) {
    85  	boring.Unreachable()
    86  	if len(src) < BlockSize {
    87  		panic("crypto/aes: input not full block")
    88  	}
    89  	if len(dst) < BlockSize {
    90  		panic("crypto/aes: output not full block")
    91  	}
    92  	if alias.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
    93  		panic("crypto/aes: invalid buffer overlap")
    94  	}
    95  	decryptBlockAsm(len(c.dec)/4-1, &c.dec[0], &dst[0], &src[0])
    96  }
    97  
    98  // expandKey is used by BenchmarkExpand to ensure that the asm implementation
    99  // of key expansion is used for the benchmark when it is available.
   100  func expandKey(key []byte, enc, dec []uint32) {
   101  	if supportsAES {
   102  		rounds := 10 // rounds needed for AES128
   103  		switch len(key) {
   104  		case 192 / 8:
   105  			rounds = 12
   106  		case 256 / 8:
   107  			rounds = 14
   108  		}
   109  		expandKeyAsm(rounds, &key[0], &enc[0], &dec[0])
   110  	} else {
   111  		expandKeyGo(key, enc, dec)
   112  	}
   113  }
   114
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