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pkg/cryptstate: get rid of ocb2.NonceSize hard-coding.

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This commit is contained in:
Mikkel Krautz 2012-12-08 22:39:24 +01:00
parent 33a7e1304d
commit 2b12adc014
1 changed files with 17 additions and 36 deletions
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53
pkg/cryptstate/cryptstate.go
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@ -82,32 +82,24 @@ func (cs *CryptState) SetKey(key []byte, eiv []byte, div []byte) error {
return nil
}
func (cs *CryptState) Decrypt(dst, src []byte) (err error) {
func (cs *CryptState) Decrypt(dst, src []byte) error {
if len(src) < 4 {
err = errors.New("Crypted length too short to decrypt")
return
return errors.New("cryptstate: crypted length too short to decrypt")
}
plain_len := len(src) - 4
if len(dst) != plain_len {
err = errors.New("plain_len and src len mismatch")
return
return errors.New("cryptstate: plain_len and src len mismatch")
}
var saveiv [ocb2.NonceSize]byte
var tag [ocb2.TagSize]byte
var ivbyte byte
var restore bool
ivbyte := src[0]
restore := false
lost := 0
late := 0
ivbyte = src[0]
restore = false
if copy(saveiv[:], cs.DecryptIV) != ocb2.NonceSize {
err = errors.New("Copy failed")
return
}
saveiv := make([]byte, len(cs.DecryptIV))
copy(saveiv, cs.DecryptIV)
if byte(cs.DecryptIV[0]+1) == ivbyte {
// In order as expected
@ -115,14 +107,14 @@ func (cs *CryptState) Decrypt(dst, src []byte) (err error) {
cs.DecryptIV[0] = ivbyte
} else if ivbyte < cs.DecryptIV[0] {
cs.DecryptIV[0] = ivbyte
for i := 1; i < ocb2.NonceSize; i++ {
for i := 1; i < len(cs.DecryptIV); i++ {
cs.DecryptIV[i] += 1
if cs.DecryptIV[i] > 0 {
break
}
}
} else {
err = errors.New("invalid ivbyte")
return errors.New("cryptstate: invalid ivbyte")
}
} else {
// Out of order or repeat
@ -145,7 +137,7 @@ func (cs *CryptState) Decrypt(dst, src []byte) (err error) {
late = 1
lost = -1
cs.DecryptIV[0] = ivbyte
for i := 1; i < ocb2.NonceSize; i++ {
for i := 1; i < len(cs.DecryptIV); i++ {
cs.DecryptIV[i] -= 1
if cs.DecryptIV[i] > 0 {
break
@ -160,22 +152,18 @@ func (cs *CryptState) Decrypt(dst, src []byte) (err error) {
// Lost a few packets, and wrapped around
lost = int(256 - int(cs.DecryptIV[0]) + int(ivbyte) - 1)
cs.DecryptIV[0] = ivbyte
for i := 1; i < ocb2.NonceSize; i++ {
for i := 1; i < len(cs.DecryptIV); i++ {
cs.DecryptIV[i] += 1
if cs.DecryptIV[i] > 0 {
break
}
}
} else {
err = errors.New("No matching ivbyte")
return
return errors.New("cryptstate: no matching ivbyte")
}
if cs.decryptHistory[cs.DecryptIV[0]] == cs.DecryptIV[0] {
if copy(cs.DecryptIV, saveiv[:]) != ocb2.NonceSize {
err = errors.New("Failed to copy ocb2.NonceSize bytes")
return
}
cs.DecryptIV = saveiv
}
}
@ -183,22 +171,15 @@ func (cs *CryptState) Decrypt(dst, src []byte) (err error) {
for i := 0; i < 3; i++ {
if tag[i] != src[i+1] {
if copy(cs.DecryptIV, saveiv[:]) != ocb2.NonceSize {
err = errors.New("Error while trying to recover from error")
return
}
err = errors.New("tag mismatch")
return
cs.DecryptIV = saveiv
return errors.New("tag mismatch")
}
}
cs.decryptHistory[cs.DecryptIV[0]] = cs.DecryptIV[0]
if restore {
if copy(cs.DecryptIV, saveiv[:]) != ocb2.NonceSize {
err = errors.New("Error while trying to recover IV")
return
}
cs.DecryptIV = saveiv
}
cs.Good += 1
@ -215,7 +196,7 @@ func (cs *CryptState) Decrypt(dst, src []byte) (err error) {
cs.LastGoodTime = time.Now().Unix()
return
return nil
}
func (cs *CryptState) Encrypt(dst, src []byte) {