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/**********************************************************************
* Copyright (c) 2020 Jonas Nick *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#ifndef _SECP256K1_MODULE_EXTRAKEYS_MAIN_
#define _SECP256K1_MODULE_EXTRAKEYS_MAIN_
#include "include/secp256k1.h"
#include "include/secp256k1_extrakeys.h"
static SECP256K1_INLINE int secp256k1_xonly_pubkey_load(const secp256k1_context* ctx, secp256k1_ge *ge, const secp256k1_xonly_pubkey *pubkey) {
return secp256k1_pubkey_load(ctx, ge, (const secp256k1_pubkey *) pubkey);
}
static SECP256K1_INLINE void secp256k1_xonly_pubkey_save(secp256k1_xonly_pubkey *pubkey, secp256k1_ge *ge) {
secp256k1_pubkey_save((secp256k1_pubkey *) pubkey, ge);
}
int secp256k1_xonly_pubkey_parse(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pubkey, const unsigned char *input32) {
secp256k1_ge pk;
secp256k1_fe x;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(pubkey != NULL);
memset(pubkey, 0, sizeof(*pubkey));
ARG_CHECK(input32 != NULL);
if (!secp256k1_fe_set_b32(&x, input32)) {
return 0;
}
if (!secp256k1_ge_set_xo_var(&pk, &x, 0)) {
return 0;
}
if (!secp256k1_ge_is_in_correct_subgroup(&pk)) {
return 0;
}
secp256k1_xonly_pubkey_save(pubkey, &pk);
return 1;
}
int secp256k1_xonly_pubkey_serialize(const secp256k1_context* ctx, unsigned char *output32, const secp256k1_xonly_pubkey *pubkey) {
secp256k1_ge pk;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(output32 != NULL);
memset(output32, 0, 32);
ARG_CHECK(pubkey != NULL);
if (!secp256k1_xonly_pubkey_load(ctx, &pk, pubkey)) {
return 0;
}
secp256k1_fe_get_b32(output32, &pk.x);
return 1;
}
/** Keeps a group element as is if it has an even Y and otherwise negates it.
* y_parity is set to 0 in the former case and to 1 in the latter case.
* Requires that the coordinates of r are normalized. */
static int secp256k1_extrakeys_ge_even_y(secp256k1_ge *r) {
int y_parity = 0;
VERIFY_CHECK(!secp256k1_ge_is_infinity(r));
if (secp256k1_fe_is_odd(&r->y)) {
secp256k1_fe_negate(&r->y, &r->y, 1);
y_parity = 1;
}
return y_parity;
}
int secp256k1_xonly_pubkey_from_pubkey(const secp256k1_context* ctx, secp256k1_xonly_pubkey *xonly_pubkey, int *pk_parity, const secp256k1_pubkey *pubkey) {
secp256k1_ge pk;
int tmp;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(xonly_pubkey != NULL);
ARG_CHECK(pubkey != NULL);
if (!secp256k1_pubkey_load(ctx, &pk, pubkey)) {
return 0;
}
tmp = secp256k1_extrakeys_ge_even_y(&pk);
if (pk_parity != NULL) {
*pk_parity = tmp;
}
secp256k1_xonly_pubkey_save(xonly_pubkey, &pk);
return 1;
}
int secp256k1_xonly_pubkey_tweak_add(const secp256k1_context* ctx, secp256k1_pubkey *output_pubkey, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
secp256k1_ge pk;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(output_pubkey != NULL);
memset(output_pubkey, 0, sizeof(*output_pubkey));
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(internal_pubkey != NULL);
ARG_CHECK(tweak32 != NULL);
if (!secp256k1_xonly_pubkey_load(ctx, &pk, internal_pubkey)
|| !secp256k1_ec_pubkey_tweak_add_helper(&ctx->ecmult_ctx, &pk, tweak32)) {
return 0;
}
secp256k1_pubkey_save(output_pubkey, &pk);
return 1;
}
int secp256k1_xonly_pubkey_tweak_add_check(const secp256k1_context* ctx, const unsigned char *tweaked_pubkey32, int tweaked_pk_parity, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
secp256k1_ge pk;
unsigned char pk_expected32[32];
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(internal_pubkey != NULL);
ARG_CHECK(tweaked_pubkey32 != NULL);
ARG_CHECK(tweak32 != NULL);
if (!secp256k1_xonly_pubkey_load(ctx, &pk, internal_pubkey)
|| !secp256k1_ec_pubkey_tweak_add_helper(&ctx->ecmult_ctx, &pk, tweak32)) {
return 0;
}
secp256k1_fe_normalize_var(&pk.x);
secp256k1_fe_normalize_var(&pk.y);
secp256k1_fe_get_b32(pk_expected32, &pk.x);
return secp256k1_memcmp_var(&pk_expected32, tweaked_pubkey32, 32) == 0
&& secp256k1_fe_is_odd(&pk.y) == tweaked_pk_parity;
}
static void secp256k1_keypair_save(secp256k1_keypair *keypair, const secp256k1_scalar *sk, secp256k1_ge *pk) {
secp256k1_scalar_get_b32(&keypair->data[0], sk);
secp256k1_pubkey_save((secp256k1_pubkey *)&keypair->data[32], pk);
}
static int secp256k1_keypair_seckey_load(const secp256k1_context* ctx, secp256k1_scalar *sk, const secp256k1_keypair *keypair) {
int ret;
ret = secp256k1_scalar_set_b32_seckey(sk, &keypair->data[0]);
/* We can declassify ret here because sk is only zero if a keypair function
* failed (which zeroes the keypair) and its return value is ignored. */
secp256k1_declassify(ctx, &ret, sizeof(ret));
ARG_CHECK(ret);
return ret;
}
/* Load a keypair into pk and sk (if non-NULL). This function declassifies pk
* and ARG_CHECKs that the keypair is not invalid. It always initializes sk and
* pk with dummy values. */
static int secp256k1_keypair_load(const secp256k1_context* ctx, secp256k1_scalar *sk, secp256k1_ge *pk, const secp256k1_keypair *keypair) {
int ret;
const secp256k1_pubkey *pubkey = (const secp256k1_pubkey *)&keypair->data[32];
/* Need to declassify the pubkey because pubkey_load ARG_CHECKs if it's
* invalid. */
secp256k1_declassify(ctx, pubkey, sizeof(*pubkey));
ret = secp256k1_pubkey_load(ctx, pk, pubkey);
if (sk != NULL) {
ret = ret && secp256k1_keypair_seckey_load(ctx, sk, keypair);
}
if (!ret) {
*pk = secp256k1_ge_const_g;
if (sk != NULL) {
*sk = secp256k1_scalar_one;
}
}
return ret;
}
int secp256k1_keypair_create(const secp256k1_context* ctx, secp256k1_keypair *keypair, const unsigned char *seckey32) {
secp256k1_scalar sk;
secp256k1_ge pk;
int ret = 0;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(keypair != NULL);
memset(keypair, 0, sizeof(*keypair));
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
ARG_CHECK(seckey32 != NULL);
ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &sk, &pk, seckey32);
secp256k1_keypair_save(keypair, &sk, &pk);
memczero(keypair, sizeof(*keypair), !ret);
secp256k1_scalar_clear(&sk);
return ret;
}
int secp256k1_keypair_pub(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const secp256k1_keypair *keypair) {
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(pubkey != NULL);
memset(pubkey, 0, sizeof(*pubkey));
ARG_CHECK(keypair != NULL);
memcpy(pubkey->data, &keypair->data[32], sizeof(*pubkey));
return 1;
}
int secp256k1_keypair_xonly_pub(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pubkey, int *pk_parity, const secp256k1_keypair *keypair) {
secp256k1_ge pk;
int tmp;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(pubkey != NULL);
memset(pubkey, 0, sizeof(*pubkey));
ARG_CHECK(keypair != NULL);
if (!secp256k1_keypair_load(ctx, NULL, &pk, keypair)) {
return 0;
}
tmp = secp256k1_extrakeys_ge_even_y(&pk);
if (pk_parity != NULL) {
*pk_parity = tmp;
}
secp256k1_xonly_pubkey_save(pubkey, &pk);
return 1;
}
int secp256k1_keypair_xonly_tweak_add(const secp256k1_context* ctx, secp256k1_keypair *keypair, const unsigned char *tweak32) {
secp256k1_ge pk;
secp256k1_scalar sk;
int y_parity;
int ret;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(keypair != NULL);
ARG_CHECK(tweak32 != NULL);
ret = secp256k1_keypair_load(ctx, &sk, &pk, keypair);
memset(keypair, 0, sizeof(*keypair));
y_parity = secp256k1_extrakeys_ge_even_y(&pk);
if (y_parity == 1) {
secp256k1_scalar_negate(&sk, &sk);
}
ret &= secp256k1_ec_seckey_tweak_add_helper(&sk, tweak32);
ret &= secp256k1_ec_pubkey_tweak_add_helper(&ctx->ecmult_ctx, &pk, tweak32);
secp256k1_declassify(ctx, &ret, sizeof(ret));
if (ret) {
secp256k1_keypair_save(keypair, &sk, &pk);
}
secp256k1_scalar_clear(&sk);
return ret;
}
#endif
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