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)
}