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bitcoin/signature: BIP143 signature support.

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We hand in the witness_script: if non-NULL, we use BIP143-style
signature hash creation.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2016-04-12 13:05:51 +09:30
parent 8545db418b
commit df5d4e3c10
6 changed files with 125 additions and 7 deletions
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107
bitcoin/tx.c
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@@ -171,8 +171,104 @@ static void add_sha(const void *data, size_t len, void *shactx_)
sha256_update(ctx, memcheck(data, len), len);
}
static void hash_prevouts(struct sha256_double *h, const struct bitcoin_tx *tx)
{
struct sha256_ctx ctx;
size_t i;
/* BIP143: If the ANYONECANPAY flag is not set, hashPrevouts is the
* double SHA256 of the serialization of all input
* outpoints */
sha256_init(&ctx);
for (i = 0; i < tx->input_count; i++) {
add_sha(&tx->input[i].txid, sizeof(tx->input[i].txid), &ctx);
add_le32(tx->input[i].index, add_sha, &ctx);
}
sha256_double_done(&ctx, h);
}
static void hash_sequence(struct sha256_double *h, const struct bitcoin_tx *tx)
{
struct sha256_ctx ctx;
size_t i;
/* BIP143: If none of the ANYONECANPAY, SINGLE, NONE sighash type
* is set, hashSequence is the double SHA256 of the serialization
* of nSequence of all inputs */
sha256_init(&ctx);
for (i = 0; i < tx->input_count; i++)
add_le32(tx->input[i].sequence_number, add_sha, &ctx);
sha256_double_done(&ctx, h);
}
/* If the sighash type is neither SINGLE nor NONE, hashOutputs is the
* double SHA256 of the serialization of all output value (8-byte
* little endian) with scriptPubKey (varInt for the length +
* script); */
static void hash_outputs(struct sha256_double *h, const struct bitcoin_tx *tx)
{
struct sha256_ctx ctx;
size_t i;
sha256_init(&ctx);
for (i = 0; i < tx->output_count; i++) {
add_le64(tx->output[i].amount, add_sha, &ctx);
add_varint_blob(tx->output[i].script,
tx->output[i].script_length,
add_sha, &ctx);
}
sha256_double_done(&ctx, h);
}
static void hash_for_segwit(struct sha256_ctx *ctx,
const struct bitcoin_tx *tx,
unsigned int input_num,
const u8 *witness_script)
{
struct sha256_double h;
/* BIP143:
*
* Double SHA256 of the serialization of:
* 1. nVersion of the transaction (4-byte little endian)
*/
add_le32(tx->version, add_sha, ctx);
/* 2. hashPrevouts (32-byte hash) */
hash_prevouts(&h, tx);
add_sha(&h, sizeof(h), ctx);
/* 3. hashSequence (32-byte hash) */
hash_sequence(&h, tx);
add_sha(&h, sizeof(h), ctx);
/* 4. outpoint (32-byte hash + 4-byte little endian) */
add_sha(&tx->input[input_num].txid, sizeof(tx->input[input_num].txid),
ctx);
add_le32(tx->input[input_num].index, add_sha, ctx);
/* 5. scriptCode of the input (varInt for the length + script) */
add_varint_blob(witness_script, tal_count(witness_script), add_sha, ctx);
/* 6. value of the output spent by this input (8-byte little end) */
add_le64(*tx->input[input_num].amount, add_sha, ctx);
/* 7. nSequence of the input (4-byte little endian) */
add_le32(tx->input[input_num].sequence_number, add_sha, ctx);
/* 8. hashOutputs (32-byte hash) */
hash_outputs(&h, tx);
add_sha(&h, sizeof(h), ctx);
/* 9. nLocktime of the transaction (4-byte little endian) */
add_le32(tx->lock_time, add_sha, ctx);
}
void sha256_tx_for_sig(struct sha256_double *h, const struct bitcoin_tx *tx,
unsigned int input_num, enum sighash_type stype)
unsigned int input_num, enum sighash_type stype,
const u8 *witness_script)
{
size_t i;
struct sha256_ctx ctx = SHA256_INIT;
@@ -185,7 +281,14 @@ void sha256_tx_for_sig(struct sha256_double *h, const struct bitcoin_tx *tx,
for (i = 0; i < tx->input_count; i++)
if (i != input_num)
assert(tx->input[i].script_length == 0);
add_tx(tx, add_sha, &ctx, false);
if (witness_script) {
/* BIP143 hashing if OP_CHECKSIG is inside witness. */
hash_for_segwit(&ctx, tx, input_num, witness_script);
} else {
/* Otherwise signature hashing never includes witness. */
add_tx(tx, add_sha, &ctx, false);
}
sha256_le32(&ctx, stype);
sha256_double_done(&ctx, h);