Refactor to prepare for pipes implementation

This commit is contained in:
Jonathan Rudenberg 2014-07-06 09:45:39 -07:00
parent 39d629fcc7
commit e36eb5dddd
2 changed files with 77 additions and 59 deletions

View File

@ -21,6 +21,7 @@ type Ciphersuite interface {
DHLen() int
CCLen() int
MACLen() int
KeyLen() (int, int)
GenerateKey(io.Reader) (Key, error)
DH(privkey, pubkey []byte) []byte
@ -33,7 +34,7 @@ type CipherContext interface {
Decrypt(authtext, ciphertext []byte) ([]byte, error)
}
const cvLen = 48
const CVLen = 48
type Key struct {
Public []byte
@ -41,34 +42,34 @@ type Key struct {
}
type Crypter struct {
Cipher Ciphersuite
SenderKey Key
ReceiverKey Key
ChainVar []byte
KDFNum int
Cipher Ciphersuite
Key Key
PeerKey Key
ChainVar []byte
KDFNum int
scratch [192]byte
scratch [64]byte
cc CipherContext
}
func (c *Crypter) noiseBody(cc CipherContext, dst []byte, padLen int, appData, header []byte) []byte {
var plaintext []byte
if plainLen := len(appData) + padLen + 4; len(c.scratch) >= plainLen {
plaintext = c.scratch[:plainLen]
func (c *Crypter) EncryptBody(dst, plaintext, authtext []byte, padLen int) []byte {
var p []byte
if plainLen := len(plaintext) + padLen + 4; len(c.scratch) >= plainLen {
p = c.scratch[:plainLen]
} else {
plaintext = make([]byte, plainLen)
p = make([]byte, plainLen)
}
copy(plaintext, appData)
if _, err := io.ReadFull(rand.Reader, plaintext[len(appData):len(appData)+padLen]); err != nil {
copy(p, plaintext)
if _, err := io.ReadFull(rand.Reader, p[len(plaintext):len(plaintext)+padLen]); err != nil {
panic(err)
}
binary.BigEndian.PutUint32(plaintext[len(appData)+padLen:], uint32(padLen))
return cc.Encrypt(dst, header, plaintext)
binary.BigEndian.PutUint32(p[len(plaintext)+padLen:], uint32(padLen))
return c.cc.Encrypt(dst, authtext, p)
}
func (c *Crypter) Encrypt(dst []byte, ephKey *Key, plaintext []byte, padLen int) ([]byte, error) {
func (c *Crypter) EncryptBox(dst []byte, ephKey *Key, plaintext []byte, padLen int) ([]byte, error) {
if len(c.ChainVar) == 0 {
c.ChainVar = make([]byte, cvLen)
c.ChainVar = make([]byte, CVLen)
}
if ephKey == nil {
k, err := c.Cipher.GenerateKey(rand.Reader)
@ -85,22 +86,27 @@ func (c *Crypter) Encrypt(dst []byte, ephKey *Key, plaintext []byte, padLen int)
dst = newDst
}
dh1 := c.Cipher.DH(ephKey.Private, c.ReceiverKey.Public)
dh2 := c.Cipher.DH(c.SenderKey.Private, c.ReceiverKey.Public)
dh1 := c.Cipher.DH(ephKey.Private, c.PeerKey.Public)
dh2 := c.Cipher.DH(c.Key.Private, c.PeerKey.Public)
cv1, cc1 := c.deriveKey(dh1, c.ChainVar)
cv2, cc2 := c.deriveKey(dh2, cv1)
c.ChainVar = cv2
dst = append(dst, ephKey.Public...)
dst = c.cipher(cc1).Encrypt(dst, ephKey.Public, c.SenderKey.Public)
return c.noiseBody(c.cipher(cc2), dst, padLen, plaintext, dst[dstPrefixLen:]), nil
dst = c.cipher(cc1).Encrypt(dst, ephKey.Public, c.Key.Public)
c.cc.Reset(cc2)
return c.EncryptBody(dst, plaintext, dst[dstPrefixLen:], padLen), nil
}
func (c *Crypter) EncryptedLen(n int) int {
return n + (2 * c.Cipher.DHLen()) + (2 * c.Cipher.MACLen()) + 4
}
func (c *Crypter) SetContext(cc []byte) {
c.cipher(cc)
}
func (c *Crypter) cipher(cc []byte) CipherContext {
if c.cc == nil {
c.cc = c.Cipher.NewCipher(cc)
@ -110,13 +116,13 @@ func (c *Crypter) cipher(cc []byte) CipherContext {
return c.cc
}
func (c *Crypter) Decrypt(ciphertext []byte) ([]byte, error) {
func (c *Crypter) DecryptBox(ciphertext []byte) ([]byte, error) {
if len(c.ChainVar) == 0 {
c.ChainVar = make([]byte, cvLen)
c.ChainVar = make([]byte, CVLen)
}
ephPubKey := ciphertext[:c.Cipher.DHLen()]
dh1 := c.Cipher.DH(c.ReceiverKey.Private, ephPubKey)
dh1 := c.Cipher.DH(c.Key.Private, ephPubKey)
cv1, cc1 := c.deriveKey(dh1, c.ChainVar)
header := ciphertext[:(2*c.Cipher.DHLen())+c.Cipher.MACLen()]
@ -125,8 +131,13 @@ func (c *Crypter) Decrypt(ciphertext []byte) ([]byte, error) {
if err != nil {
return nil, err
}
if len(c.PeerKey.Public) > 0 {
if len(c.PeerKey.Public) != len(senderPubKey) || subtle.ConstantTimeCompare(senderPubKey, c.PeerKey.Public) != 1 {
return nil, errors.New("pipe: unexpected sender public key")
}
}
dh2 := c.Cipher.DH(c.ReceiverKey.Private, senderPubKey)
dh2 := c.Cipher.DH(c.Key.Private, senderPubKey)
cv2, cc2 := c.deriveKey(dh2, cv1)
c.ChainVar = cv2
body, err := c.cipher(cc2).Decrypt(header, ciphertext)
@ -138,33 +149,36 @@ func (c *Crypter) Decrypt(ciphertext []byte) ([]byte, error) {
return body[:len(body)-(padLen+4)], nil
}
func (c *Crypter) deriveKey(dh, cv []byte) ([]byte, []byte) {
// info || (byte)c || t[0:32] || extra_data
data := append(append(c.scratch[:0:128], cv...), 0)
data = data[:len(data)+32]
data = c.Cipher.AppendName(data)
data = strconv.AppendInt(data, int64(c.KDFNum), 10)
t := c.scratch[cap(data):]
k := deriveKey(dh, data, t, cvLen, cvLen+c.Cipher.CCLen())
c.KDFNum++
return k[:cvLen], k[cvLen:]
func (c *Crypter) DecryptBody(authtext, ciphertext []byte) ([]byte, error) {
if c.cc == nil {
return nil, errors.New("box: uninitialized cipher context")
}
return c.cc.Decrypt(authtext, ciphertext)
}
func deriveKey(secret, data, t []byte, infoLen, outputLen int) []byte {
output := make([]byte, 0, outputLen)
func (c *Crypter) deriveKey(dh, cv []byte) ([]byte, []byte) {
extra := strconv.AppendInt(c.Cipher.AppendName(c.scratch[:0]), int64(c.KDFNum), 10)
k := DeriveKey(dh, extra, cv, CVLen+c.Cipher.CCLen())
c.KDFNum++
return k[:CVLen], k[CVLen:]
}
func DeriveKey(secret, extra, info []byte, outputLen int) []byte {
buf := make([]byte, outputLen+sha512.Size)
output := buf[:0:outputLen]
t := buf[outputLen:]
h := hmac.New(sha512.New, secret)
var c byte
for len(output) < outputLen {
data[infoLen] = c
copy(data[infoLen+1:], t[:32])
h.Write(data)
h.Write(info)
h.Write([]byte{c})
h.Write(t[:32])
h.Write(extra)
t = h.Sum(t[:0])
h.Reset()
c++
if cap(output)-len(output) < len(t) {
output = append(output, t[:cap(output)-len(output)]...)
if outputLen-len(output) < len(t) {
output = append(output, t[:outputLen-len(output)]...)
} else {
output = append(output, t...)
}
@ -195,6 +209,10 @@ func (noise255) GenerateKey(random io.Reader) (Key, error) {
return Key{Private: privKey[:], Public: pubKey[:]}, nil
}
func (noise255) KeyLen() (int, int) {
return 32, 32
}
func (noise255) DH(privkey, pubkey []byte) []byte {
var dst, in, base [32]byte
copy(in[:], privkey)

View File

@ -18,21 +18,21 @@ func (s *S) TestRoundtrip(c *C) {
plain := []byte("yellow submarines")
padLen := 2
ciphertext, err := enc.Encrypt(nil, nil, plain, padLen)
ciphertext, err := enc.EncryptBox(nil, nil, plain, padLen)
c.Assert(err, IsNil)
expectedLen := len(plain) + padLen + (2 * Noise255.DHLen()) + (2 * Noise255.MACLen()) + 4
c.Assert(ciphertext, HasLen, expectedLen, Commentf("expected: %d", expectedLen))
plaintext, err := dec.Decrypt(ciphertext)
plaintext, err := dec.DecryptBox(ciphertext)
c.Assert(err, IsNil)
c.Assert(plaintext, DeepEquals, plain)
plain[0] = 'Y'
ciphertext, err = enc.Encrypt(nil, nil, plain, 0)
ciphertext, err = enc.EncryptBox(nil, nil, plain, 0)
c.Assert(err, IsNil)
plaintext, err = dec.Decrypt(ciphertext)
plaintext, err = dec.DecryptBox(ciphertext)
c.Assert(err, IsNil)
c.Assert(plaintext, DeepEquals, plain)
}
@ -42,27 +42,27 @@ func newCrypters() (*Crypter, *Crypter) {
sendKey, _ := Noise255.GenerateKey(rand.Reader)
enc := &Crypter{
Cipher: Noise255,
SenderKey: sendKey,
ReceiverKey: recvKey,
Cipher: Noise255,
Key: sendKey,
PeerKey: recvKey,
}
enc.ReceiverKey.Private = nil
enc.PeerKey.Private = nil
dec := &Crypter{
Cipher: Noise255,
SenderKey: sendKey,
ReceiverKey: recvKey,
Cipher: Noise255,
Key: recvKey,
PeerKey: sendKey,
}
dec.SenderKey.Private = nil
dec.PeerKey.Private = nil
return enc, dec
}
func BenchmarkEncrypt(b *testing.B) {
func BenchmarkEncryptBox(b *testing.B) {
enc, _ := newCrypters()
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
enc.Encrypt(nil, nil, []byte("yellow submarine"), 0)
enc.EncryptBox(nil, nil, []byte("yellow submarine"), 0)
}
}