logos-messaging/noise
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Use scratch buffer to build plaintext

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This commit is contained in:
Jonathan Rudenberg 2014-07-05 20:46:15 -07:00
parent 67a4951c9d
commit 39d629fcc7
1 changed files with 20 additions and 15 deletions
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35
box/box.go
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@ -40,16 +40,6 @@ type Key struct {
Private []byte
}
func noiseBody(cc CipherContext, dst []byte, padLen int, appData, header []byte) []byte {
plaintext := make([]byte, len(appData)+padLen+4)
copy(plaintext, appData)
if _, err := io.ReadFull(rand.Reader, plaintext[len(appData):len(appData)+padLen]); err != nil {
panic(err)
}
binary.BigEndian.PutUint32(plaintext[len(appData)+padLen:], uint32(padLen))
return cc.Encrypt(dst, header, plaintext)
}
type Crypter struct {
Cipher Ciphersuite
SenderKey Key
@ -57,8 +47,23 @@ type Crypter struct {
ChainVar []byte
KDFNum int
keyBuf [192]byte
cc CipherContext
scratch [192]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]
} else {
plaintext = make([]byte, plainLen)
}
copy(plaintext, appData)
if _, err := io.ReadFull(rand.Reader, plaintext[len(appData):len(appData)+padLen]); err != nil {
panic(err)
}
binary.BigEndian.PutUint32(plaintext[len(appData)+padLen:], uint32(padLen))
return cc.Encrypt(dst, header, plaintext)
}
func (c *Crypter) Encrypt(dst []byte, ephKey *Key, plaintext []byte, padLen int) ([]byte, error) {
@ -89,7 +94,7 @@ func (c *Crypter) Encrypt(dst []byte, ephKey *Key, plaintext []byte, padLen int)
dst = append(dst, ephKey.Public...)
dst = c.cipher(cc1).Encrypt(dst, ephKey.Public, c.SenderKey.Public)
return noiseBody(c.cipher(cc2), dst, padLen, plaintext, dst[dstPrefixLen:]), nil
return c.noiseBody(c.cipher(cc2), dst, padLen, plaintext, dst[dstPrefixLen:]), nil
}
func (c *Crypter) EncryptedLen(n int) int {
@ -135,12 +140,12 @@ func (c *Crypter) Decrypt(ciphertext []byte) ([]byte, error) {
func (c *Crypter) deriveKey(dh, cv []byte) ([]byte, []byte) {
// info || (byte)c || t[0:32] || extra_data
data := append(append(c.keyBuf[:0:128], cv...), 0)
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.keyBuf[cap(data):]
t := c.scratch[cap(data):]
k := deriveKey(dh, data, t, cvLen, cvLen+c.Cipher.CCLen())
c.KDFNum++