Function cryptomsg_decrypt_header

common/cryptomsg.c:123–152

}

bool cryptomsg_decrypt_header(struct crypto_state *cs, const u8 hdr[18],
			      u16 *lenp)
{
	unsigned char npub[crypto_aead_chacha20poly1305_ietf_NPUBBYTES];
	unsigned long long mlen;
	be16 len;

	le64_nonce(npub, cs->rn++);

	/* BOLT #8:
	 *
	 *  2. Let the encrypted length prefix be known as `lc`.
	 *  3. Decrypt `lc` (using `ChaCha20-Poly1305`, `rn`, and `rk`), to
	 *     obtain the size of the encrypted packet `l`.
	 *    * A zero-length byte slice is to be passed as the AD
	 *	(associated data).
	 *    * The nonce `rn` MUST be incremented after this step.
	 */
	if (crypto_aead_chacha20poly1305_ietf_decrypt((unsigned char *)&len,
						      &mlen, NULL,
						      memcheck(hdr, 18), 18,
						      NULL, 0,
						      npub, cs->rk.data) != 0) {
		/* FIXME: Report error! */
		return false;
	}
	assert(mlen == sizeof(len));
	*lenp = be16_to_cpu(len);
	return true;
}

u8 *cryptomsg_encrypt_msg(const tal_t *ctx,
			  struct crypto_state *cs,