Bitcoin Core  0.19.99
P2P Digital Currency
ecmult_gen.h
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1 /**********************************************************************
2  * Copyright (c) 2013, 2014 Pieter Wuille *
3  * Distributed under the MIT software license, see the accompanying *
4  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
5  **********************************************************************/
6 
7 #ifndef SECP256K1_ECMULT_GEN_H
8 #define SECP256K1_ECMULT_GEN_H
9 
10 #include "scalar.h"
11 #include "group.h"
12 
13 typedef struct {
14  /* For accelerating the computation of a*G:
15  * To harden against timing attacks, use the following mechanism:
16  * * Break up the multiplicand into groups of 4 bits, called n_0, n_1, n_2, ..., n_63.
17  * * Compute sum(n_i * 16^i * G + U_i, i=0..63), where:
18  * * U_i = U * 2^i (for i=0..62)
19  * * U_i = U * (1-2^63) (for i=63)
20  * where U is a point with no known corresponding scalar. Note that sum(U_i, i=0..63) = 0.
21  * For each i, and each of the 16 possible values of n_i, (n_i * 16^i * G + U_i) is
22  * precomputed (call it prec(i, n_i)). The formula now becomes sum(prec(i, n_i), i=0..63).
23  * None of the resulting prec group elements have a known scalar, and neither do any of
24  * the intermediate sums while computing a*G.
25  */
26  secp256k1_ge_storage (*prec)[64][16]; /* prec[j][i] = 16^j * i * G + U_i */
30 
34  const secp256k1_ecmult_gen_context* src, const secp256k1_callback* cb);
37 
40 
41 static void secp256k1_ecmult_gen_blind(secp256k1_ecmult_gen_context *ctx, const unsigned char *seed32);
42 
43 #endif /* SECP256K1_ECMULT_GEN_H */
static void secp256k1_ecmult_gen(const secp256k1_ecmult_gen_context *ctx, secp256k1_gej *r, const secp256k1_scalar *a)
Multiply with the generator: R = a*G.
static void secp256k1_ecmult_gen_context_clone(secp256k1_ecmult_gen_context *dst, const secp256k1_ecmult_gen_context *src, const secp256k1_callback *cb)
static void secp256k1_ecmult_gen_blind(secp256k1_ecmult_gen_context *ctx, const unsigned char *seed32)
A group element of the secp256k1 curve, in jacobian coordinates.
Definition: group.h:24
static void secp256k1_ecmult_gen_context_build(secp256k1_ecmult_gen_context *ctx, const secp256k1_callback *cb)
static void secp256k1_ecmult_gen_context_clear(secp256k1_ecmult_gen_context *ctx)
secp256k1_scalar blind
Definition: ecmult_gen.h:27
static secp256k1_context * ctx
Definition: tests.c:46
A scalar modulo the group order of the secp256k1 curve.
Definition: scalar_4x64.h:13
static void secp256k1_ecmult_gen_context_init(secp256k1_ecmult_gen_context *ctx)
static int secp256k1_ecmult_gen_context_is_built(const secp256k1_ecmult_gen_context *ctx)