diff options
Diffstat (limited to 'src/secp256k1/src/modules/extrakeys/main_impl.h')
| -rw-r--r-- | src/secp256k1/src/modules/extrakeys/main_impl.h | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/src/secp256k1/src/modules/extrakeys/main_impl.h b/src/secp256k1/src/modules/extrakeys/main_impl.h new file mode 100644 index 0000000000..d319215355 --- /dev/null +++ b/src/secp256k1/src/modules/extrakeys/main_impl.h @@ -0,0 +1,248 @@ +/********************************************************************** + * 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; + } + 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 memcmp(&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 |