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Add `secp256k1_ec_pubkey_negate` and `secp256k1_ec_privkey_negate`

master
Andrew Poelstra 6 years ago
parent
commit
8e48aa60dc
  1. 22
      include/secp256k1.h
  2. 27
      src/secp256k1.c
  3. 26
      src/tests.c

22
include/secp256k1.h

@ -491,6 +491,28 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create( @@ -491,6 +491,28 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
const unsigned char *seckey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Negates a private key in place.
*
* Returns: 1 always
* Args: ctx: pointer to a context object
* In/Out: pubkey: pointer to the public key to be negated (cannot be NULL)
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_negate(
const secp256k1_context* ctx,
unsigned char *seckey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Negates a public key in place.
*
* Returns: 1 always
* Args: ctx: pointer to a context object
* In/Out: pubkey: pointer to the public key to be negated (cannot be NULL)
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_negate(
const secp256k1_context* ctx,
secp256k1_pubkey *pubkey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Tweak a private key by adding tweak to it.
* Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
* uniformly random 32-byte arrays, or if the resulting private key

27
src/secp256k1.c

@ -424,6 +424,33 @@ int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *p @@ -424,6 +424,33 @@ int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *p
return ret;
}
int secp256k1_ec_privkey_negate(const secp256k1_context* ctx, unsigned char *seckey) {
secp256k1_scalar sec;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(seckey != NULL);
secp256k1_scalar_set_b32(&sec, seckey, NULL);
secp256k1_scalar_negate(&sec, &sec);
secp256k1_scalar_get_b32(seckey, &sec);
return 1;
}
int secp256k1_ec_pubkey_negate(const secp256k1_context* ctx, secp256k1_pubkey *pubkey) {
int ret = 0;
secp256k1_ge p;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(pubkey != NULL);
ret = secp256k1_pubkey_load(ctx, &p, pubkey);
memset(pubkey, 0, sizeof(*pubkey));
if (ret) {
secp256k1_ge_neg(&p, &p);
secp256k1_pubkey_save(pubkey, &p);
}
return ret;
}
int secp256k1_ec_privkey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
secp256k1_scalar term;
secp256k1_scalar sec;

26
src/tests.c

@ -10,6 +10,7 @@ @@ -10,6 +10,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
@ -135,6 +136,7 @@ void random_scalar_order(secp256k1_scalar *num) { @@ -135,6 +136,7 @@ void random_scalar_order(secp256k1_scalar *num) {
void run_context_tests(void) {
secp256k1_pubkey pubkey;
secp256k1_pubkey zero_pubkey;
secp256k1_ecdsa_signature sig;
unsigned char ctmp[32];
int32_t ecount;
@ -149,6 +151,8 @@ void run_context_tests(void) { @@ -149,6 +151,8 @@ void run_context_tests(void) {
secp256k1_scalar msg, key, nonce;
secp256k1_scalar sigr, sigs;
memset(&zero_pubkey, 0, sizeof(zero_pubkey));
ecount = 0;
ecount2 = 10;
secp256k1_context_set_illegal_callback(vrfy, counting_illegal_callback_fn, &ecount);
@ -201,12 +205,20 @@ void run_context_tests(void) { @@ -201,12 +205,20 @@ void run_context_tests(void) {
CHECK(ecount == 2);
CHECK(secp256k1_ec_pubkey_tweak_mul(sign, &pubkey, ctmp) == 0);
CHECK(ecount2 == 13);
CHECK(secp256k1_ec_pubkey_tweak_mul(vrfy, &pubkey, ctmp) == 1);
CHECK(secp256k1_ec_pubkey_negate(vrfy, &pubkey) == 1);
CHECK(ecount == 2);
CHECK(secp256k1_context_randomize(vrfy, ctmp) == 0);
CHECK(secp256k1_ec_pubkey_negate(sign, &pubkey) == 1);
CHECK(ecount == 2);
CHECK(secp256k1_ec_pubkey_negate(sign, NULL) == 0);
CHECK(ecount2 == 14);
CHECK(secp256k1_ec_pubkey_negate(vrfy, &zero_pubkey) == 0);
CHECK(ecount == 3);
CHECK(secp256k1_ec_pubkey_tweak_mul(vrfy, &pubkey, ctmp) == 1);
CHECK(ecount == 3);
CHECK(secp256k1_context_randomize(vrfy, ctmp) == 0);
CHECK(ecount == 4);
CHECK(secp256k1_context_randomize(sign, NULL) == 1);
CHECK(ecount2 == 13);
CHECK(ecount2 == 14);
secp256k1_context_set_illegal_callback(vrfy, NULL, NULL);
secp256k1_context_set_illegal_callback(sign, NULL, NULL);
@ -3436,6 +3448,7 @@ void test_ecdsa_end_to_end(void) { @@ -3436,6 +3448,7 @@ void test_ecdsa_end_to_end(void) {
unsigned char pubkeyc[65];
size_t pubkeyclen = 65;
secp256k1_pubkey pubkey;
secp256k1_pubkey pubkey_tmp;
unsigned char seckey[300];
size_t seckeylen = 300;
@ -3457,6 +3470,13 @@ void test_ecdsa_end_to_end(void) { @@ -3457,6 +3470,13 @@ void test_ecdsa_end_to_end(void) {
memset(&pubkey, 0, sizeof(pubkey));
CHECK(secp256k1_ec_pubkey_parse(ctx, &pubkey, pubkeyc, pubkeyclen) == 1);
/* Verify negation changes the key and changes it back */
memcpy(&pubkey_tmp, &pubkey, sizeof(pubkey));
CHECK(secp256k1_ec_pubkey_negate(ctx, &pubkey_tmp) == 1);
CHECK(memcmp(&pubkey_tmp, &pubkey, sizeof(pubkey)) != 0);
CHECK(secp256k1_ec_pubkey_negate(ctx, &pubkey_tmp) == 1);
CHECK(memcmp(&pubkey_tmp, &pubkey, sizeof(pubkey)) == 0);
/* Verify private key import and export. */
CHECK(ec_privkey_export_der(ctx, seckey, &seckeylen, privkey, secp256k1_rand_bits(1) == 1));
CHECK(ec_privkey_import_der(ctx, privkey2, seckey, seckeylen) == 1);

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