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electrum 4/5 improve speed by avoiding secp256k1_ec_pubkey_serialize

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philsmd 2019-11-16 20:53:28 +01:00 committed by GitHub
parent c4dd020685
commit 8839504daa
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 35 additions and 7 deletions
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42
src/ext_secp256k1.c
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@ -60,17 +60,45 @@ bool hc_secp256k1_pubkey_parse (secp256k1_pubkey *pubkey, u8 *buf, size_t length
bool hc_secp256k1_pubkey_tweak_mul (secp256k1_pubkey *pubkey, u8 *buf, size_t length)
{
secp256k1_context *sctx = secp256k1_context_create (SECP256K1_CONTEXT_VERIFY);
secp256k1_context *sctx = secp256k1_context_create (SECP256K1_CONTEXT_NONE);
if (secp256k1_ec_pubkey_tweak_mul (sctx, pubkey, buf) == 0)
{
secp256k1_context_destroy (sctx);
secp256k1_gej res;
secp256k1_ge pt;
return false;
}
// load the public key:
secp256k1_ec_pubkey_serialize (sctx, buf, &length, pubkey, SECP256K1_EC_COMPRESSED);
secp256k1_pubkey_load (sctx, &pt, pubkey);
int overflow = 0;
secp256k1_scalar s;
secp256k1_scalar_set_b32 (&s, buf, &overflow);
if (overflow) return false;
if (secp256k1_scalar_is_zero (&s)) return false;
// main multiply operation:
const size_t scalar_size = (length - 1) * 8;
secp256k1_ecmult_const (&res, &pt, &s, scalar_size);
secp256k1_ge_set_gej (&pt, &res);
secp256k1_fe_normalize (&pt.x);
secp256k1_fe_normalize (&pt.y);
// output:
buf[0] = 0x02 | secp256k1_fe_is_odd (&pt.y);
secp256k1_fe_get_b32 (buf + 1, &pt.x);
// cleanup:
secp256k1_scalar_clear (&s);
secp256k1_context_destroy (sctx);
return true;