예제 #1
0
파일: owned.go 프로젝트: ineiti/prifi
func (c *ownedCoder) ownerEncode(payload, payout []byte, p abstract.Point) {

	// XXX trap-encode

	// Pick a fresh random key with which to encrypt the payload
	key := make([]byte, c.keylen)
	c.random.XORKeyStream(key, key)

	// Encrypt the payload with it
	c.suite.Cipher(key).XORKeyStream(payout, payload)

	// Compute a MAC over the encrypted payload
	h := c.suite.Hash()
	h.Write(payout)
	mac := h.Sum(nil)[:c.maclen]

	// Combine the key and the MAC into the Point for this cell header
	hdr := append(key, mac...)
	if len(hdr) != p.PickLen() {
		panic("oops, length of key+mac turned out wrong")
	}
	mp, _ := c.suite.Point().Pick(hdr, c.random)

	// Add this to the blinding point we already computed to transmit.
	p.Add(p, mp)
}