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a5fedc4e1f
> If the peer's revocation basepoint is unknown (e.g. `open_channel2`), > a temporary `channel_id` should be found by using a zeroed out basepoint > for the unknown peer.
97 lines
2.8 KiB
C
97 lines
2.8 KiB
C
#include <bitcoin/pubkey.h>
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#include <bitcoin/tx.h>
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#include <common/channel_id.h>
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#include <common/pseudorand.h>
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#include <common/type_to_string.h>
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#include <wire/wire.h>
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void derive_channel_id(struct channel_id *channel_id,
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const struct bitcoin_txid *txid, u16 txout)
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{
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BUILD_ASSERT(sizeof(*channel_id) == sizeof(*txid));
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memcpy(channel_id, txid, sizeof(*channel_id));
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channel_id->id[sizeof(*channel_id)-2] ^= txout >> 8;
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channel_id->id[sizeof(*channel_id)-1] ^= txout;
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}
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void derive_channel_id_v2(struct channel_id *channel_id,
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const struct pubkey *basepoint_1,
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const struct pubkey *basepoint_2)
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{
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/* BOLT-f53ca2301232db780843e894f55d95d512f297f9 #2:
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* `channel_id`, v2
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* For channels established using the v2 protocol, the
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* `channel_id` is the
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* SHA256(lesser-revocation-basepoint ||
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* greater-revocation-basepoint),
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* where the lesser and greater is based off the order of
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* the basepoint. The basepoints are compact
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* DER-encoded public keys.
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*/
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u8 der_keys[PUBKEY_CMPR_LEN * 2];
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struct sha256 sha;
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int offset_1, offset_2;
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/* basepoint_1 is first? */
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if (pubkey_idx(basepoint_1, basepoint_2) == 0) {
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offset_1 = 0;
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offset_2 = PUBKEY_CMPR_LEN;
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} else {
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offset_1 = PUBKEY_CMPR_LEN;
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offset_2 = 0;
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}
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pubkey_to_der(der_keys + offset_1, basepoint_1);
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pubkey_to_der(der_keys + offset_2, basepoint_2);
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sha256(&sha, der_keys, sizeof(der_keys));
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BUILD_ASSERT(sizeof(*channel_id) == sizeof(sha));
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memcpy(channel_id, &sha, sizeof(*channel_id));
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}
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void derive_tmp_channel_id(struct channel_id *channel_id,
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const struct pubkey *opener_basepoint)
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{
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struct sha256 sha;
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/* BOLT-f53ca2301232db780843e894f55d95d512f297f9 #2:
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* If the peer's revocation basepoint is unknown
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* (e.g. `open_channel2`), a temporary `channel_id` should be
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* found by using a zeroed out basepoint for the unknown peer.
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*/
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u8 der_keys[PUBKEY_CMPR_LEN * 2];
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memset(der_keys, 0, PUBKEY_CMPR_LEN);
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pubkey_to_der(der_keys + PUBKEY_CMPR_LEN, opener_basepoint);
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sha256(&sha, der_keys, sizeof(der_keys));
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BUILD_ASSERT(sizeof(*channel_id) == sizeof(sha));
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memcpy(channel_id, &sha, sizeof(*channel_id));
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}
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/* BOLT #2:
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*
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* The sending node:
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*...
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* - MUST ensure `temporary_channel_id` is unique from any other channel ID
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* with the same peer.
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*/
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void temporary_channel_id(struct channel_id *channel_id)
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{
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size_t i;
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/* Randomness FTW. */
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for (i = 0; i < sizeof(*channel_id); i++)
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channel_id->id[i] = pseudorand(256);
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}
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void towire_channel_id(u8 **pptr, const struct channel_id *channel_id)
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{
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towire(pptr, channel_id, sizeof(*channel_id));
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}
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void fromwire_channel_id(const u8 **cursor, size_t *max,
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struct channel_id *channel_id)
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{
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fromwire(cursor, max, channel_id, sizeof(*channel_id));
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}
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REGISTER_TYPE_TO_HEXSTR(channel_id);
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