52 lines
1.6 KiB
C
52 lines
1.6 KiB
C
/***********************************************************************
|
|
* Copyright (c) 2015 Gregory Maxwell *
|
|
* Distributed under the MIT software license, see the accompanying *
|
|
* file COPYING or http://www.opensource.org/licenses/mit-license.php. *
|
|
***********************************************************************/
|
|
|
|
#ifndef _SECP256K1_PEDERSEN_IMPL_H_
|
|
#define _SECP256K1_PEDERSEN_IMPL_H_
|
|
|
|
#include <string.h>
|
|
|
|
#include "eckey.h"
|
|
#include "ecmult_const.h"
|
|
#include "ecmult_gen.h"
|
|
#include "group.h"
|
|
#include "field.h"
|
|
#include "scalar.h"
|
|
#include "util.h"
|
|
|
|
static void secp256k1_pedersen_scalar_set_u64(secp256k1_scalar *sec, uint64_t value) {
|
|
unsigned char data[32];
|
|
int i;
|
|
for (i = 0; i < 24; i++) {
|
|
data[i] = 0;
|
|
}
|
|
for (; i < 32; i++) {
|
|
data[i] = value >> 56;
|
|
value <<= 8;
|
|
}
|
|
secp256k1_scalar_set_b32(sec, data, NULL);
|
|
memset(data, 0, 32);
|
|
}
|
|
|
|
static void secp256k1_pedersen_ecmult_small(secp256k1_gej *r, uint64_t gn, const secp256k1_ge* genp) {
|
|
secp256k1_scalar s;
|
|
secp256k1_pedersen_scalar_set_u64(&s, gn);
|
|
secp256k1_ecmult_const(r, genp, &s, 64);
|
|
secp256k1_scalar_clear(&s);
|
|
}
|
|
|
|
/* sec * G + value * G2. */
|
|
SECP256K1_INLINE static void secp256k1_pedersen_ecmult(const secp256k1_ecmult_gen_context *ecmult_gen_ctx, secp256k1_gej *rj, const secp256k1_scalar *sec, uint64_t value, const secp256k1_ge* genp) {
|
|
secp256k1_gej vj;
|
|
secp256k1_ecmult_gen(ecmult_gen_ctx, rj, sec);
|
|
secp256k1_pedersen_ecmult_small(&vj, value, genp);
|
|
/* FIXME: constant time. */
|
|
secp256k1_gej_add_var(rj, rj, &vj, NULL);
|
|
secp256k1_gej_clear(&vj);
|
|
}
|
|
|
|
#endif
|