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