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noise
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Update Noise255 to match changes in spec

This commit is contained in:
Jonathan Rudenberg 2014-07-13 23:27:31 -07:00
parent e0ed980c97
commit d3253d3baa
1 changed files with 28 additions and 9 deletions
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37
box/box.go
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@ -228,7 +228,7 @@ func (noise255) NewCipher(cc []byte) CipherContext {
type noise255ctx struct {
cc []byte
keystream [128]byte
keystream [104]byte
}
func (n *noise255ctx) Reset(cc []byte) {
@ -244,14 +244,31 @@ func (n *noise255ctx) key() (cipher.Stream, []byte) {
panic(err)
}
for i := range n.keystream {
keystream := n.keystream[:64]
for i := range keystream {
n.keystream[i] = 0
}
c.XORKeyStream(keystream, keystream)
c.XORKeyStream(n.keystream[:], n.keystream[:])
return c, keystream
}
n.cc = n.keystream[64:104]
return c, n.keystream[:]
func (n *noise255ctx) rekey() {
cipherKey := n.cc[:32]
iv := n.cc[32:40]
for i := range iv {
iv[i] ^= 0xff
}
c, err := chacha20.NewCipher(cipherKey, iv)
if err != nil {
panic(err)
}
n.cc = n.keystream[64:]
for i := range n.cc {
n.cc[i] = 0
}
c.XORKeyStream(n.cc, n.cc)
}
func (n *noise255ctx) mac(keystream, ciphertext, authtext []byte) [16]byte {
@ -266,6 +283,7 @@ func (n *noise255ctx) Encrypt(dst, plaintext, authtext []byte) []byte {
c, keystream := n.key()
ciphertext := make([]byte, len(plaintext), len(plaintext)+16)
c.XORKeyStream(ciphertext, plaintext)
n.rekey()
tag := n.mac(keystream, ciphertext, authtext)
return append(dst, append(ciphertext, tag[:]...)...)
}
@ -284,22 +302,23 @@ func (n *noise255ctx) Decrypt(ciphertext, authtext []byte) ([]byte, error) {
plaintext := make([]byte, len(ciphertext))
c.XORKeyStream(plaintext, ciphertext)
n.rekey()
return plaintext, nil
}
func (noise255ctx) authData(ciphertext, authtext []byte) []byte {
// PAD16(authtext) || PAD16(ciphertext) || (uint64)len(authtext) || (uint64)len(ciphertext)
// PAD16(authtext) || PAD16(ciphertext) || (uint64_little_endian)len(authtext) || (uint64_little_endian)len(ciphertext)
authData := make([]byte, pad16len(len(authtext))+pad16len(len(ciphertext))+8+8)
copy(authData, authtext)
offset := pad16len(len(authtext))
copy(authData[offset:], ciphertext)
offset += pad16len(len(ciphertext))
binary.BigEndian.PutUint64(authData[offset:], uint64(len(authtext)))
binary.LittleEndian.PutUint64(authData[offset:], uint64(len(authtext)))
offset += 8
binary.BigEndian.PutUint64(authData[offset:], uint64(len(ciphertext)))
binary.LittleEndian.PutUint64(authData[offset:], uint64(len(ciphertext)))
return authData
}
func pad16len(l int) int {
return l + (16 - (l % 16))
return l + ((16 - (l % 16)) % 16)
}