Differential D19817 Diff 58992 src/secp256k1/examples/ecdsa.c

Changeset View

Standalone View

src/secp256k1/examples/ecdsa.c

/*************************************************************************		/*************************************************************************
* Written in 2020-2022 by Elichai Turkel *		* Written in 2020-2022 by Elichai Turkel *
* To the extent possible under law, the author(s) have dedicated all *		* To the extent possible under law, the author(s) have dedicated all *
* copyright and related and neighboring rights to the software in this *		* copyright and related and neighboring rights to the software in this *
* file to the public domain worldwide. This software is distributed *		* file to the public domain worldwide. This software is distributed *
* without any warranty. For the CC0 Public Domain Dedication, see *		* without any warranty. For the CC0 Public Domain Dedication, see *
* EXAMPLES_COPYING or https://creativecommons.org/publicdomain/zero/1.0 *		* EXAMPLES_COPYING or https://creativecommons.org/publicdomain/zero/1.0 *
*************************************************************************/		*************************************************************************/

#include <stdio.h>		#include <stdio.h>
#include <assert.h>		#include <assert.h>
#include <string.h>		#include <string.h>

#include <secp256k1.h>		#include <secp256k1.h>

#include "random.h"		#include "examples_util.h"



int main(void) {		int main(void) {
/* Instead of signing the message directly, we must sign a 32-byte hash.		/* Instead of signing the message directly, we must sign a 32-byte hash.
* Here the message is "Hello, world!" and the hash function was SHA-256.		* Here the message is "Hello, world!" and the hash function was SHA-256.
* An actual implementation should just call SHA-256, but this example		* An actual implementation should just call SHA-256, but this example
* hardcodes the output to avoid depending on an additional library.		* hardcodes the output to avoid depending on an additional library.
* See https://bitcoin.stackexchange.com/questions/81115/if-someone-wanted-to-pretend-to-be-satoshi-by-posting-a-fake-signature-to-defrau/81116#81116 */		* See https://bitcoin.stackexchange.com/questions/81115/if-someone-wanted-to-pretend-to-be-satoshi-by-posting-a-fake-signature-to-defrau/81116#81116 */
unsigned char msg_hash[32] = {		unsigned char msg_hash[32] = {
▲ Show 20 Lines • Show All 93 Lines • ▼ Show 20 Lines	int main(void) {
/* This will clear everything from the context and free the memory */		/* This will clear everything from the context and free the memory */
secp256k1_context_destroy(ctx);		secp256k1_context_destroy(ctx);

/* It's best practice to try to clear secrets from memory after using them.		/* It's best practice to try to clear secrets from memory after using them.
* This is done because some bugs can allow an attacker to leak memory, for		* This is done because some bugs can allow an attacker to leak memory, for
* example through "out of bounds" array access (see Heartbleed), Or the OS		* example through "out of bounds" array access (see Heartbleed), Or the OS
* swapping them to disk. Hence, we overwrite the secret key buffer with zeros.		* swapping them to disk. Hence, we overwrite the secret key buffer with zeros.
*		*
* TODO: Prevent these writes from being optimized out, as any good compiler		* Here we are preventing these writes from being optimized out, as any good compiler
* will remove any writes that aren't used. */		* will remove any writes that aren't used. */
memset(seckey, 0, sizeof(seckey));		secure_erase(seckey, sizeof(seckey));

return 0;		return 0;
}		}