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secp256k1
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Separate helper functions for pubkey_create and seckey_tweak_add 

This is in preparation for allowing code reuse by keypair functions
This commit is contained in:
Jonas Nick 2020-05-12 14:43:48 +00:00
parent 910d9c284c
commit f0010349b8
1 changed files with 28 additions and 14 deletions
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42
src/secp256k1.c
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@ -549,10 +549,21 @@ int secp256k1_ec_seckey_verify(const secp256k1_context* ctx, const unsigned char
return ret; return ret;
} }
int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *seckey) { static int secp256k1_ec_pubkey_create_helper(const secp256k1_ecmult_gen_context *ecmult_gen_ctx, secp256k1_scalar *seckey_scalar, secp256k1_ge *p, const unsigned char *seckey) {
secp256k1_gej pj; secp256k1_gej pj;
int ret;
ret = secp256k1_scalar_set_b32_seckey(seckey_scalar, seckey);
secp256k1_scalar_cmov(seckey_scalar, &secp256k1_scalar_one, !ret);
secp256k1_ecmult_gen(ecmult_gen_ctx, &pj, seckey_scalar);
secp256k1_ge_set_gej(p, &pj);
return ret;
}
int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *seckey) {
secp256k1_ge p; secp256k1_ge p;
secp256k1_scalar sec; secp256k1_scalar seckey_scalar;
int ret = 0; int ret = 0;
VERIFY_CHECK(ctx != NULL); VERIFY_CHECK(ctx != NULL);
ARG_CHECK(pubkey != NULL); ARG_CHECK(pubkey != NULL);
@ -560,15 +571,11 @@ int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *p
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx)); ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
ARG_CHECK(seckey != NULL); ARG_CHECK(seckey != NULL);
ret = secp256k1_scalar_set_b32_seckey(&sec, seckey); ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &seckey_scalar, &p, seckey);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_one, !ret);
secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &pj, &sec);
secp256k1_ge_set_gej(&p, &pj);
secp256k1_pubkey_save(pubkey, &p); secp256k1_pubkey_save(pubkey, &p);
memczero(pubkey, sizeof(*pubkey), !ret); memczero(pubkey, sizeof(*pubkey), !ret);
secp256k1_scalar_clear(&sec); secp256k1_scalar_clear(&seckey_scalar);
return ret; return ret;
} }
@ -606,24 +613,31 @@ int secp256k1_ec_pubkey_negate(const secp256k1_context* ctx, secp256k1_pubkey *p
return ret; return ret;
} }
int secp256k1_ec_seckey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
static int secp256k1_ec_seckey_tweak_add_helper(secp256k1_scalar *sec, const unsigned char *tweak) {
secp256k1_scalar term; secp256k1_scalar term;
int overflow = 0;
int ret = 0;
secp256k1_scalar_set_b32(&term, tweak, &overflow);
ret = (!overflow) & secp256k1_eckey_privkey_tweak_add(sec, &term);
secp256k1_scalar_clear(&term);
return ret;
}
int secp256k1_ec_seckey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
secp256k1_scalar sec; secp256k1_scalar sec;
int ret = 0; int ret = 0;
int overflow = 0;
VERIFY_CHECK(ctx != NULL); VERIFY_CHECK(ctx != NULL);
ARG_CHECK(seckey != NULL); ARG_CHECK(seckey != NULL);
ARG_CHECK(tweak != NULL); ARG_CHECK(tweak != NULL);
secp256k1_scalar_set_b32(&term, tweak, &overflow);
ret = secp256k1_scalar_set_b32_seckey(&sec, seckey); ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
ret &= secp256k1_ec_seckey_tweak_add_helper(&sec, tweak);
ret &= (!overflow) & secp256k1_eckey_privkey_tweak_add(&sec, &term);
secp256k1_scalar_cmov(&sec, &secp256k1_scalar_zero, !ret); secp256k1_scalar_cmov(&sec, &secp256k1_scalar_zero, !ret);
secp256k1_scalar_get_b32(seckey, &sec); secp256k1_scalar_get_b32(seckey, &sec);
secp256k1_scalar_clear(&sec); secp256k1_scalar_clear(&sec);
secp256k1_scalar_clear(&term);
return ret; return ret;
} }