core-lightning/open-commit-sig.c
Rusty Russell ed3f0115d6 protocol: fix horribly thinko, keep own secrets.
I had each side using the other side's hash secret.  That's a very
dumb idea, since it means you can steal from a unilateral close!

A's secret applies to A's commit transaction: it needs the
secret and B's final signature to steal funds, and that should
never happen (since A doesn't have the B's final signature, and
once A has given B the secret, they never broadcast the commit tx).

This makes the update a 4 step dance, since you need the new
revocation hash to make the other side's TX to sign.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-06-10 21:39:45 +09:30

98 lines
3.0 KiB
C

/* My example:
* ./open-commit-sig A-open.pb B-open.pb cUBCjrdJu8tfvM7FT8So6aqs6G6bZS1Cax6Rc9rFzYL6nYG4XNEC A-leak-anchor-sigs.pb B-leak-anchor-sigs.pb > A-commit-sig.pb
* ./open-commit-sig B-open.pb A-open.pb cQXhbUnNRsFcdzTQwjbCrud5yVskHTEas7tZPUWoJYNk5htGQrpi B-leak-anchor-sigs.pb A-leak-anchor-sigs.pb > B-commit-sig.pb
*/
#include <ccan/crypto/shachain/shachain.h>
#include <ccan/short_types/short_types.h>
#include <ccan/tal/tal.h>
#include <ccan/opt/opt.h>
#include <ccan/str/hex/hex.h>
#include <ccan/err/err.h>
#include <ccan/read_write_all/read_write_all.h>
#include "lightning.pb-c.h"
#include "anchor.h"
#include "base58.h"
#include "pkt.h"
#include "bitcoin_script.h"
#include "permute_tx.h"
#include "signature.h"
#include "commit_tx.h"
#include "pubkey.h"
#include <openssl/ec.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
const tal_t *ctx = tal_arr(NULL, char, 0);
OpenChannel *o1, *o2;
struct bitcoin_tx *anchor, *commit;
struct sha256_double txid;
struct pkt *pkt;
struct signature sig;
size_t *inmap, *outmap;
EC_KEY *privkey;
bool testnet;
struct pubkey pubkey1, pubkey2;
u8 *subscript;
struct sha256 rhash;
err_set_progname(argv[0]);
opt_register_noarg("--help|-h", opt_usage_and_exit,
"<open-channel-file1> <open-channel-file2> <commit-privkey> <leak-anchor-sigs1> <leak-anchor-sigs2>\n"
"Create the signature needed for the commit transaction",
"Print this message.");
opt_parse(&argc, argv, opt_log_stderr_exit);
if (argc != 6)
opt_usage_exit_fail("Expected 5 arguments");
o1 = pkt_from_file(argv[1], PKT__PKT_OPEN)->open;
o2 = pkt_from_file(argv[2], PKT__PKT_OPEN)->open;
privkey = key_from_base58(argv[3], strlen(argv[3]), &testnet, &pubkey1);
if (!privkey)
errx(1, "Invalid private key '%s'", argv[3]);
if (!testnet)
errx(1, "Private key '%s' not on testnet!", argv[3]);
/* Create merged anchor transaction */
anchor = anchor_tx_create(ctx, o1, o2, &inmap, &outmap);
if (!anchor)
errx(1, "Failed transaction merge");
/* Get the transaction ID of the anchor. */
anchor_txid(anchor, argv[4], argv[5], inmap, &txid);
/* Now create THEIR commitment tx to spend 2/2 output of anchor. */
proto_to_sha256(o2->revocation_hash, &rhash);
commit = create_commit_tx(ctx, o2, o1, &rhash, 0, &txid, outmap[0]);
/* If contributions don't exceed fees, this fails. */
if (!commit)
errx(1, "Contributions %llu & %llu vs fees %llu & %llu",
(long long)o1->anchor->total,
(long long)o2->anchor->total,
(long long)o1->commitment_fee,
(long long)o2->commitment_fee);
/* Their pubkey must be valid */
if (!proto_to_pubkey(o2->anchor->pubkey, &pubkey2))
errx(1, "Invalid public open-channel-file2");
/* Sign it for them. */
subscript = bitcoin_redeem_2of2(ctx, &pubkey1, &pubkey2);
sign_tx_input(ctx, commit, 0, subscript, tal_count(subscript),
privkey, &pubkey1, &sig);
pkt = open_commit_sig_pkt(ctx, &sig);
if (!write_all(STDOUT_FILENO, pkt,
sizeof(pkt->len) + le32_to_cpu(pkt->len)))
err(1, "Writing out packet");
tal_free(ctx);
return 0;
}