elgamal_test.go

Documentation: golang.org/x/crypto/openpgp/elgamal

     1  // Copyright 2011 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 elgamal
     6  
     7  import (
     8  	"bytes"
     9  	"crypto/rand"
    10  	"math/big"
    11  	"testing"
    12  )
    13  
    14  // This is the 1024-bit MODP group from RFC 5114, section 2.1:
    15  const primeHex = "B10B8F96A080E01DDE92DE5EAE5D54EC52C99FBCFB06A3C69A6A9DCA52D23B616073E28675A23D189838EF1E2EE652C013ECB4AEA906112324975C3CD49B83BFACCBDD7D90C4BD7098488E9C219A73724EFFD6FAE5644738FAA31A4FF55BCCC0A151AF5F0DC8B4BD45BF37DF365C1A65E68CFDA76D4DA708DF1FB2BC2E4A4371"
    16  
    17  const generatorHex = "A4D1CBD5C3FD34126765A442EFB99905F8104DD258AC507FD6406CFF14266D31266FEA1E5C41564B777E690F5504F213160217B4B01B886A5E91547F9E2749F4D7FBD7D3B9A92EE1909D0D2263F80A76A6A24C087A091F531DBF0A0169B6A28AD662A4D18E73AFA32D779D5918D08BC8858F4DCEF97C2A24855E6EEB22B3B2E5"
    18  
    19  func fromHex(hex string) *big.Int {
    20  	n, ok := new(big.Int).SetString(hex, 16)
    21  	if !ok {
    22  		panic("failed to parse hex number")
    23  	}
    24  	return n
    25  }
    26  
    27  func TestEncryptDecrypt(t *testing.T) {
    28  	priv := &PrivateKey{
    29  		PublicKey: PublicKey{
    30  			G: fromHex(generatorHex),
    31  			P: fromHex(primeHex),
    32  		},
    33  		X: fromHex("42"),
    34  	}
    35  	priv.Y = new(big.Int).Exp(priv.G, priv.X, priv.P)
    36  
    37  	message := []byte("hello world")
    38  	c1, c2, err := Encrypt(rand.Reader, &priv.PublicKey, message)
    39  	if err != nil {
    40  		t.Errorf("error encrypting: %s", err)
    41  	}
    42  	message2, err := Decrypt(priv, c1, c2)
    43  	if err != nil {
    44  		t.Errorf("error decrypting: %s", err)
    45  	}
    46  	if !bytes.Equal(message2, message) {
    47  		t.Errorf("decryption failed, got: %x, want: %x", message2, message)
    48  	}
    49  }
    50  
    51  func TestDecryptBadKey(t *testing.T) {
    52  	priv := &PrivateKey{
    53  		PublicKey: PublicKey{
    54  			G: fromHex(generatorHex),
    55  			P: fromHex("2"),
    56  		},
    57  		X: fromHex("42"),
    58  	}
    59  	priv.Y = new(big.Int).Exp(priv.G, priv.X, priv.P)
    60  	c1, c2 := fromHex("8"), fromHex("8")
    61  	if _, err := Decrypt(priv, c1, c2); err == nil {
    62  		t.Errorf("unexpected success decrypting")
    63  	}
    64  }
    65
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