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crypto/cipher: fix OCFB

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I messed up when reading the OCFB spec.

TBR=rsc

R=rsc
CC=golang-dev
https://golang.org/cl/3739042
This commit is contained in:
Adam Langley 2010-12-27 12:55:49 -05:00
parent 784788ba44
commit 03e259664f
1 changed files with 25 additions and 4 deletions
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29
src/pkg/crypto/cipher/ocfb.go
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@ -6,7 +6,7 @@
package cipher
type ocfb struct {
type ocfbEncrypter struct {
b Block
fre []byte
outUsed int
@ -22,7 +22,7 @@ func NewOCFBEncrypter(block Block, randData []byte) (Stream, []byte) {
return nil, nil
}
x := &ocfb{
x := &ocfbEncrypter{
b: block,
fre: make([]byte, blockSize),
outUsed: 0,
@ -42,6 +42,25 @@ func NewOCFBEncrypter(block Block, randData []byte) (Stream, []byte) {
return x, prefix
}
func (x *ocfbEncrypter) XORKeyStream(dst, src []byte) {
for i := 0; i < len(src); i++ {
if x.outUsed == len(x.fre) {
x.b.Encrypt(x.fre, x.fre)
x.outUsed = 0
}
x.fre[x.outUsed] ^= src[i]
dst[i] = x.fre[x.outUsed]
x.outUsed++
}
}
type ocfbDecrypter struct {
b Block
fre []byte
outUsed int
}
// NewOCFBDecrypter returns a Stream which decrypts data with OpenPGP's cipher
// feedback mode using the given Block. Prefix must be the first blockSize + 2
// bytes of the ciphertext, where blockSize is the Block's block size. If an
@ -52,7 +71,7 @@ func NewOCFBDecrypter(block Block, prefix []byte) Stream {
return nil
}
x := &ocfb{
x := &ocfbDecrypter{
b: block,
fre: make([]byte, blockSize),
outUsed: 0,
@ -78,14 +97,16 @@ func NewOCFBDecrypter(block Block, prefix []byte) Stream {
return x
}
func (x *ocfb) XORKeyStream(dst, src []byte) {
func (x *ocfbDecrypter) XORKeyStream(dst, src []byte) {
for i := 0; i < len(src); i++ {
if x.outUsed == len(x.fre) {
x.b.Encrypt(x.fre, x.fre)
x.outUsed = 0
}
c := src[i]
dst[i] = x.fre[x.outUsed] ^ src[i]
x.fre[x.outUsed] = c
x.outUsed++
}
}