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#include <bitcoin/pubkey.h>
#include <bitcoin/shadouble.h>
#include <ccan/crypto/sha256/sha256.h>
#include <ccan/err/err.h>
#include <ccan/short_types/short_types.h>
#include <common/bech32.h>
#include <common/utils.h>
#include <secp256k1_recovery.h>
#include <stdio.h>
#include <wally_core.h>
/* These tables copied from zbase32 src:
* copyright 2002-2007 Zooko "Zooko" Wilcox-O'Hearn
* mailto:zooko@zooko.com
*
* Permission is hereby granted to any person obtaining a copy of this work to
* deal in this work without restriction (including the rights to use, modify,
* distribute, sublicense, and/or sell copies).
*/
/* revchars: index into this table with the ASCII value of the char. The result is the value of that quintet. */
static const u8 zbase32_revchars[]={ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 18, 255, 25, 26, 27, 30, 29, 7, 31, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 24, 1, 12, 3, 8, 5, 6, 28, 21, 9, 10, 255, 11, 2, 16, 13, 14, 4, 22, 17, 19, 255, 20, 15, 0, 23, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, };
static void usage(void)
{
fprintf(stderr, "Usage: lightning-checkmessage message zbase32-sig [key]\n"
"If key does not match, signature is not valid!\n");
exit(1);
}
int main(int argc, char *argv[])
{
u8 *u5sig, *u8sig;
size_t len;
secp256k1_ecdsa_recoverable_signature rsig;
struct sha256_ctx sctx = SHA256_INIT;
struct sha256_double shad;
struct pubkey reckey;
const char *keystr;
setup_locale();
err_set_progname(argv[0]);
wally_init(0);
secp256k1_ctx = wally_get_secp_context();
if (argc != 3 && argc != 4)
usage();
u5sig = tal_arr(NULL, u8, strlen(argv[2]));
for (size_t i = 0; argv[2][i]; i++) {
u5sig[i] = zbase32_revchars[(unsigned char)argv[2][i]];
if (u5sig[i] > 31)
errx(1, "Not a valid zbase32 string");
}
u8sig = tal_arr(NULL, u8, (strlen(argv[2]) * 5 + 7) / 8 + 1);
len = 0;
if (!bech32_convert_bits(u8sig, &len, 8, u5sig, strlen(argv[2]), 5, false))
errx(1, "Invalid string");
if (len != 65)
errx(1, "Signature too %s", len < 65 ? "short" : "long");
if (!secp256k1_ecdsa_recoverable_signature_parse_compact(secp256k1_ctx,
&rsig,
u8sig + 1,
u8sig[0] - 31))
errx(1, "Signature not parsable");
sha256_update(&sctx, "Lightning Signed Message:",
strlen("Lightning Signed Message:"));
sha256_update(&sctx, argv[1], strlen(argv[1]));
sha256_double_done(&sctx, &shad);
if (!secp256k1_ecdsa_recover(secp256k1_ctx, &reckey.pubkey, &rsig,
shad.sha.u.u8))
errx(1, "Signature not recoverable");
keystr = pubkey_to_hexstr(NULL, &reckey);
if (argv[3]) {
if (!streq(keystr, argv[3]))
errx(1, "Signature is invalid");
printf("Signature is valid!\n");
} else
printf("Signature claims to be from key %s\n", keystr);
return 0;
}