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crypto/cipher: add package

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cipher is intended to replace crypto/block over time. This
change only adds basic parts: CBC and CTR mode and doesn't add
the package to the top-level Makefile.

R=r, rsc
CC=golang-dev
https://golang.org/cl/3069041
This commit is contained in:
Adam Langley 2010-11-19 14:12:07 -05:00
parent ad21c42f05
commit 07791d04d6
8 changed files with 481 additions and 0 deletions
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14
src/pkg/crypto/cipher/Makefile Normal file
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# Copyright 2010 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
include ../../../Make.inc
TARG=crypto/cipher
GOFILES=\
cbc.go\
cipher.go\
ctr.go\
io.go
include ../../../Make.pkg

78
src/pkg/crypto/cipher/cbc.go Normal file
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Cipher block chaining (CBC) mode.
// CBC provides confidentiality by xoring (chaining) each plaintext block
// with the previous ciphertext block before applying the block cipher.
// See NIST SP 800-38A, pp 10-11
package cipher
type cbc struct {
b Block
blockSize int
iv []byte
tmp []byte
}
func newCBC(b Block, iv []byte) *cbc {
return &cbc{
b: b,
blockSize: b.BlockSize(),
iv: dup(iv),
tmp: make([]byte, b.BlockSize()),
}
}
type cbcEncrypter cbc
// NewCBCEncrypter returns a BlockMode which encrypts in cipher block chaining
// mode, using the given Block. The length of iv must be the same as the
// Block's block size.
func NewCBCEncrypter(b Block, iv []byte) BlockMode {
return (*cbcEncrypter)(newCBC(b, iv))
}
func (x *cbcEncrypter) BlockSize() int { return x.blockSize }
func (x *cbcEncrypter) CryptBlocks(dst, src []byte) {
for len(src) > 0 {
for i := 0; i < x.blockSize; i++ {
x.iv[i] ^= src[i]
}
x.b.Encrypt(x.iv, x.iv)
for i := 0; i < x.blockSize; i++ {
dst[i] = x.iv[i]
}
src = src[x.blockSize:]
dst = dst[x.blockSize:]
}
}
type cbcDecrypter cbc
// NewCBCDecrypter returns a BlockMode which decrypts in cipher block chaining
// mode, using the given Block. The length of iv must be the same as the
// Block's block size as must match the iv used to encrypt the data.
func NewCBCDecrypter(b Block, iv []byte) *cbcDecrypter {
return (*cbcDecrypter)(newCBC(b, iv))
}
func (x *cbcDecrypter) BlockSize() int { return x.blockSize }
func (x *cbcDecrypter) CryptBlocks(dst, src []byte) {
for len(src) > 0 {
x.b.Decrypt(x.tmp, src[:x.blockSize])
for i := 0; i < x.blockSize; i++ {
x.tmp[i] ^= x.iv[i]
x.iv[i] = src[i]
dst[i] = x.tmp[i]
}
src = src[x.blockSize:]
dst = dst[x.blockSize:]
}
}

89
src/pkg/crypto/cipher/cbc_aes_test.go Normal file
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// CBC AES test vectors.
// See U.S. National Institute of Standards and Technology (NIST)
// Special Publication 800-38A, ``Recommendation for Block Cipher
// Modes of Operation,'' 2001 Edition, pp. 24-29.
package cipher
import (
"bytes"
"crypto/aes"
"testing"
)
var cbcAESTests = []struct {
name string
key []byte
iv []byte
in []byte
out []byte
}{
// NIST SP 800-38A pp 27-29
{
"CBC-AES128",
commonKey128,
commonIV,
commonInput,
[]byte{
0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46, 0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d,
0x50, 0x86, 0xcb, 0x9b, 0x50, 0x72, 0x19, 0xee, 0x95, 0xdb, 0x11, 0x3a, 0x91, 0x76, 0x78, 0xb2,
0x73, 0xbe, 0xd6, 0xb8, 0xe3, 0xc1, 0x74, 0x3b, 0x71, 0x16, 0xe6, 0x9e, 0x22, 0x22, 0x95, 0x16,
0x3f, 0xf1, 0xca, 0xa1, 0x68, 0x1f, 0xac, 0x09, 0x12, 0x0e, 0xca, 0x30, 0x75, 0x86, 0xe1, 0xa7,
},
},
{
"CBC-AES192",
commonKey192,
commonIV,
commonInput,
[]byte{
0x4f, 0x02, 0x1d, 0xb2, 0x43, 0xbc, 0x63, 0x3d, 0x71, 0x78, 0x18, 0x3a, 0x9f, 0xa0, 0x71, 0xe8,
0xb4, 0xd9, 0xad, 0xa9, 0xad, 0x7d, 0xed, 0xf4, 0xe5, 0xe7, 0x38, 0x76, 0x3f, 0x69, 0x14, 0x5a,
0x57, 0x1b, 0x24, 0x20, 0x12, 0xfb, 0x7a, 0xe0, 0x7f, 0xa9, 0xba, 0xac, 0x3d, 0xf1, 0x02, 0xe0,
0x08, 0xb0, 0xe2, 0x79, 0x88, 0x59, 0x88, 0x81, 0xd9, 0x20, 0xa9, 0xe6, 0x4f, 0x56, 0x15, 0xcd,
},
},
{
"CBC-AES256",
commonKey256,
commonIV,
commonInput,
[]byte{
0xf5, 0x8c, 0x4c, 0x04, 0xd6, 0xe5, 0xf1, 0xba, 0x77, 0x9e, 0xab, 0xfb, 0x5f, 0x7b, 0xfb, 0xd6,
0x9c, 0xfc, 0x4e, 0x96, 0x7e, 0xdb, 0x80, 0x8d, 0x67, 0x9f, 0x77, 0x7b, 0xc6, 0x70, 0x2c, 0x7d,
0x39, 0xf2, 0x33, 0x69, 0xa9, 0xd9, 0xba, 0xcf, 0xa5, 0x30, 0xe2, 0x63, 0x04, 0x23, 0x14, 0x61,
0xb2, 0xeb, 0x05, 0xe2, 0xc3, 0x9b, 0xe9, 0xfc, 0xda, 0x6c, 0x19, 0x07, 0x8c, 0x6a, 0x9d, 0x1b,
},
},
}
func TestCBC_AES(t *testing.T) {
for _, tt := range cbcAESTests {
test := tt.name
c, err := aes.NewCipher(tt.key)
if err != nil {
t.Errorf("%s: NewCipher(%d bytes) = %s", test, len(tt.key), err)
continue
}
encrypter := NewCBCEncrypter(c, tt.iv)
d := make([]byte, len(tt.in))
encrypter.CryptBlocks(d, tt.in)
if !bytes.Equal(tt.out, d) {
t.Errorf("%s: CBCEncrypter\nhave %x\nwant %x", test, d, tt.out)
}
decrypter := NewCBCDecrypter(c, tt.iv)
p := make([]byte, len(d))
decrypter.CryptBlocks(p, d)
if !bytes.Equal(tt.in, p) {
t.Errorf("%s: CBCDecrypter\nhave %x\nwant %x", test, d, tt.in)
}
}
}

63
src/pkg/crypto/cipher/cipher.go Normal file
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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// The cipher package implements standard block cipher modes
// that can be wrapped around low-level block cipher implementations.
// See http://csrc.nist.gov/groups/ST/toolkit/BCM/current_modes.html
// and NIST Special Publication 800-38A.
package cipher
// A Block represents an implementation of block cipher
// using a given key. It provides the capability to encrypt
// or decrypt individual blocks. The mode implementations
// extend that capability to streams of blocks.
type Block interface {
// BlockSize returns the cipher's block size.
BlockSize() int
// Encrypt encrypts the first block in src into dst.
// Dst and src may point at the same memory.
Encrypt(dst, src []byte)
// Decrypt decrypts the first block in src into dst.
// Dst and src may point at the same memory.
Decrypt(dst, src []byte)
}
// A Stream represents a stream cipher.
type Stream interface {
// XORKeyStream XORs each byte in the given slice with a byte from the
// cipher's key stream. Dst and src may point to the same memory.
XORKeyStream(dst, src []byte)
}
// A BlockMode represents a block cipher running in a block-based mode (CBC,
// ECB etc).
type BlockMode interface {
// BlockSize returns the mode's block size.
BlockSize() int
// CryptBlocks encrypts or decrypts a number of blocks. The length of
// src must be a multiple of the block size. Dst and src may point to
// the same memory.
CryptBlocks(dst, src []byte)
}
// Utility routines
func shift1(dst, src []byte) byte {
var b byte
for i := len(src) - 1; i >= 0; i-- {
bb := src[i] >> 7
dst[i] = src[i]<<1 | b
b = bb
}
return b
}
func dup(p []byte) []byte {
q := make([]byte, len(p))
copy(q, p)
return q
}

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src/pkg/crypto/cipher/common_test.go Normal file
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package cipher
// Common values for tests.
var commonInput = []byte{
0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10,
}
var commonKey128 = []byte{0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c}
var commonKey192 = []byte{
0x8e, 0x73, 0xb0, 0xf7, 0xda, 0x0e, 0x64, 0x52, 0xc8, 0x10, 0xf3, 0x2b, 0x80, 0x90, 0x79, 0xe5,
0x62, 0xf8, 0xea, 0xd2, 0x52, 0x2c, 0x6b, 0x7b,
}
var commonKey256 = []byte{
0x60, 0x3d, 0xeb, 0x10, 0x15, 0xca, 0x71, 0xbe, 0x2b, 0x73, 0xae, 0xf0, 0x85, 0x7d, 0x77, 0x81,
0x1f, 0x35, 0x2c, 0x07, 0x3b, 0x61, 0x08, 0xd7, 0x2d, 0x98, 0x10, 0xa3, 0x09, 0x14, 0xdf, 0xf4,
}
var commonIV = []byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f}

51
src/pkg/crypto/cipher/ctr.go Normal file
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Counter (CTR) mode.
// CTR converts a block cipher into a stream cipher by
// repeatedly encrypting an incrementing counter and
// xoring the resulting stream of data with the input.
// See NIST SP 800-38A, pp 13-15
package cipher
type ctr struct {
b Block
ctr []byte
out []byte
outUsed int
}
// NewCTR returns a Stream which encrypts/decrypts using the given Block in
// counter mode. The length of iv must be the same as the Block's block size.
func NewCTR(block Block, iv []byte) Stream {
return &ctr{
b: block,
ctr: dup(iv),
out: make([]byte, len(iv)),
outUsed: len(iv),
}
}
func (x *ctr) XORKeyStream(dst, src []byte) {
for i := 0; i < len(src); i++ {
if x.outUsed == len(x.ctr) {
x.b.Encrypt(x.out, x.ctr)
x.outUsed = 0
// Increment counter
for i := len(x.ctr) - 1; i >= 0; i-- {
x.ctr[i]++
if x.ctr[i] != 0 {
break
}
}
}
dst[i] = src[i] ^ x.out[x.outUsed]
x.outUsed++
}
}

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src/pkg/crypto/cipher/ctr_aes_test.go Normal file
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// CTR AES test vectors.
// See U.S. National Institute of Standards and Technology (NIST)
// Special Publication 800-38A, ``Recommendation for Block Cipher
// Modes of Operation,'' 2001 Edition, pp. 55-58.
package cipher
import (
"bytes"
"crypto/aes"
"testing"
)
var commonCounter = []byte{0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff}
var ctrAESTests = []struct {
name string
key []byte
iv []byte
in []byte
out []byte
}{
// NIST SP 800-38A pp 55-58
{
"CTR-AES128",
commonKey128,
commonCounter,
commonInput,
[]byte{
0x87, 0x4d, 0x61, 0x91, 0xb6, 0x20, 0xe3, 0x26, 0x1b, 0xef, 0x68, 0x64, 0x99, 0x0d, 0xb6, 0xce,
0x98, 0x06, 0xf6, 0x6b, 0x79, 0x70, 0xfd, 0xff, 0x86, 0x17, 0x18, 0x7b, 0xb9, 0xff, 0xfd, 0xff,
0x5a, 0xe4, 0xdf, 0x3e, 0xdb, 0xd5, 0xd3, 0x5e, 0x5b, 0x4f, 0x09, 0x02, 0x0d, 0xb0, 0x3e, 0xab,
0x1e, 0x03, 0x1d, 0xda, 0x2f, 0xbe, 0x03, 0xd1, 0x79, 0x21, 0x70, 0xa0, 0xf3, 0x00, 0x9c, 0xee,
},
},
{
"CTR-AES192",
commonKey192,
commonCounter,
commonInput,
[]byte{
0x1a, 0xbc, 0x93, 0x24, 0x17, 0x52, 0x1c, 0xa2, 0x4f, 0x2b, 0x04, 0x59, 0xfe, 0x7e, 0x6e, 0x0b,
0x09, 0x03, 0x39, 0xec, 0x0a, 0xa6, 0xfa, 0xef, 0xd5, 0xcc, 0xc2, 0xc6, 0xf4, 0xce, 0x8e, 0x94,
0x1e, 0x36, 0xb2, 0x6b, 0xd1, 0xeb, 0xc6, 0x70, 0xd1, 0xbd, 0x1d, 0x66, 0x56, 0x20, 0xab, 0xf7,
0x4f, 0x78, 0xa7, 0xf6, 0xd2, 0x98, 0x09, 0x58, 0x5a, 0x97, 0xda, 0xec, 0x58, 0xc6, 0xb0, 0x50,
},
},
{
"CTR-AES256",
commonKey256,
commonCounter,
commonInput,
[]byte{
0x60, 0x1e, 0xc3, 0x13, 0x77, 0x57, 0x89, 0xa5, 0xb7, 0xa7, 0xf5, 0x04, 0xbb, 0xf3, 0xd2, 0x28,
0xf4, 0x43, 0xe3, 0xca, 0x4d, 0x62, 0xb5, 0x9a, 0xca, 0x84, 0xe9, 0x90, 0xca, 0xca, 0xf5, 0xc5,
0x2b, 0x09, 0x30, 0xda, 0xa2, 0x3d, 0xe9, 0x4c, 0xe8, 0x70, 0x17, 0xba, 0x2d, 0x84, 0x98, 0x8d,
0xdf, 0xc9, 0xc5, 0x8d, 0xb6, 0x7a, 0xad, 0xa6, 0x13, 0xc2, 0xdd, 0x08, 0x45, 0x79, 0x41, 0xa6,
},
},
}
func TestCTR_AES(t *testing.T) {
for _, tt := range ctrAESTests {
test := tt.name
c, err := aes.NewCipher(tt.key)
if err != nil {
t.Errorf("%s: NewCipher(%d bytes) = %s", test, len(tt.key), err)
continue
}
for j := 0; j <= 5; j += 5 {
in := tt.in[0 : len(tt.in)-j]
ctr := NewCTR(c, tt.iv)
encrypted := make([]byte, len(in))
ctr.XORKeyStream(encrypted, in)
if out := tt.out[0:len(in)]; !bytes.Equal(out, encrypted) {
t.Errorf("%s/%d: CTR\ninpt %x\nhave %x\nwant %x", test, len(in), in, encrypted, out)
}
}
for j := 0; j <= 7; j += 7 {
in := tt.out[0 : len(tt.out)-j]
ctr := NewCTR(c, tt.iv)
plain := make([]byte, len(in))
ctr.XORKeyStream(plain, in)
if out := tt.in[0:len(in)]; !bytes.Equal(out, plain) {
t.Errorf("%s/%d: CTRReader\nhave %x\nwant %x", test, len(out), plain, out)
}
}
if t.Failed() {
break
}
}
}

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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package cipher
import (
"os"
"io"
)
// The Stream* objects are so simple that all their members are public. Users
// can create them themselves.
// StreamReader wraps a Stream into an io.Reader. It simply calls XORKeyStream
// to process each slice of data which passes through.
type StreamReader struct {
S Stream
R io.Reader
}
func (r StreamReader) Read(dst []byte) (n int, err os.Error) {
n, err = r.R.Read(dst)
r.S.XORKeyStream(dst[:n], dst[:n])
return
}
// StreamWriter wraps a Stream into an io.Writer. It simply calls XORKeyStream
// to process each slice of data which passes through. If any Write call
// returns short then the StreamWriter is out of sync and must be discarded.
type StreamWriter struct {
S Stream
W io.Writer
Err os.Error
}
func (w StreamWriter) Write(src []byte) (n int, err os.Error) {
if w.Err != nil {
return 0, w.Err
}
c := make([]byte, len(src))
w.S.XORKeyStream(c, src)
n, err = w.W.Write(c)
if n != len(src) {
if err == nil { // should never happen
err = io.ErrShortWrite
}
w.Err = err
}
return
}
func (w StreamWriter) Close() os.Error {
// This saves us from either requiring a WriteCloser or having a
// StreamWriterCloser.
return w.W.(io.Closer).Close()
}