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 `/**********************************************************************` ` * Copyright (c) 2013, 2014 Pieter Wuille *` ` * Distributed under the MIT software license, see the accompanying *` ` * file COPYING or http://www.opensource.org/licenses/mit-license.php.*` ` **********************************************************************/` ``` ``` `#ifndef _SECP256K1_ECMULT_GEN_` `#define _SECP256K1_ECMULT_GEN_` `#include "scalar.h"` `#include "group.h"` `typedef struct {` ` /* For accelerating the computation of a*G:` ` * To harden against timing attacks, use the following mechanism:` ` * * Break up the multiplicand into groups of 4 bits, called n_0, n_1, n_2, ..., n_63.` ` * * Compute sum(n_i * 16^i * G + U_i, i=0..63), where:` ` * * U_i = U * 2^i (for i=0..62)` ` * * U_i = U * (1-2^63) (for i=63)` ` * where U is a point with no known corresponding scalar. Note that sum(U_i, i=0..63) = 0.` ` * For each i, and each of the 16 possible values of n_i, (n_i * 16^i * G + U_i) is` ` * precomputed (call it prec(i, n_i)). The formula now becomes sum(prec(i, n_i), i=0..63).` ` * None of the resulting prec group elements have a known scalar, and neither do any of` ` * the intermediate sums while computing a*G.` ` */` ` secp256k1_ge_storage_t (*prec)[64][16]; /* prec[j][i] = 16^j * i * G + U_i */` ` secp256k1_scalar_t blind;` ` secp256k1_gej_t initial;` `} secp256k1_ecmult_gen_context_t;` ``` ``` `static void secp256k1_ecmult_gen_context_init(secp256k1_ecmult_gen_context_t* ctx);` `static void secp256k1_ecmult_gen_context_build(secp256k1_ecmult_gen_context_t* ctx);` `static void secp256k1_ecmult_gen_context_clone(secp256k1_ecmult_gen_context_t *dst,` ` const secp256k1_ecmult_gen_context_t* src);` `static void secp256k1_ecmult_gen_context_clear(secp256k1_ecmult_gen_context_t* ctx);` `static int secp256k1_ecmult_gen_context_is_built(const secp256k1_ecmult_gen_context_t* ctx);` ``` ``` `/** Multiply with the generator: R = a*G */` `static void secp256k1_ecmult_gen(const secp256k1_ecmult_gen_context_t* ctx, secp256k1_gej_t *r, const secp256k1_scalar_t *a);` ``` ``` `static void secp256k1_ecmult_gen_blind(secp256k1_ecmult_gen_context_t *ctx, const unsigned char *seed32);` ``` ``` ```#endif ``` ``` ```