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Switch to C89 comments in prep for making the whole codebase C89 compatible.

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This should be whitespace/comment only changes and should produce the same
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This commit is contained in:
Gregory Maxwell
2014-11-15 15:28:10 +00:00
parent 21288f2d05
commit 71712b27e5
38 changed files with 802 additions and 716 deletions
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60
src/ecmult_gen_impl.h
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@@ -1,6 +1,8 @@
// 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.
/**********************************************************************
* 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_IMPL_H_
#define _SECP256K1_ECMULT_GEN_IMPL_H_
@@ -10,19 +12,19 @@
#include "ecmult_gen.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.
// To make memory access uniform, the bytes of prec(i, n_i) are sliced per value of n_i.
unsigned char prec[64][sizeof(secp256k1_ge_t)][16]; // prec[j][k][i] = k'th byte of (16^j * i * G + U_i)
/* 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.
* To make memory access uniform, the bytes of prec(i, n_i) are sliced per value of n_i. */
unsigned char prec[64][sizeof(secp256k1_ge_t)][16]; /* prec[j][k][i] = k'th byte of (16^j * i * G + U_i) */
} secp256k1_ecmult_gen_consts_t;
static const secp256k1_ecmult_gen_consts_t *secp256k1_ecmult_gen_consts = NULL;
@@ -31,14 +33,14 @@ static void secp256k1_ecmult_gen_start(void) {
if (secp256k1_ecmult_gen_consts != NULL)
return;
// Allocate the precomputation table.
/* Allocate the precomputation table. */
secp256k1_ecmult_gen_consts_t *ret = (secp256k1_ecmult_gen_consts_t*)malloc(sizeof(secp256k1_ecmult_gen_consts_t));
// get the generator
/* get the generator */
const secp256k1_ge_t *g = &secp256k1_ge_consts->g;
secp256k1_gej_t gj; secp256k1_gej_set_ge(&gj, g);
// Construct a group element with no known corresponding scalar (nothing up my sleeve).
/* Construct a group element with no known corresponding scalar (nothing up my sleeve). */
secp256k1_gej_t nums_gej;
{
static const unsigned char nums_b32[32] = "The scalar for this x is unknown";
@@ -47,30 +49,30 @@ static void secp256k1_ecmult_gen_start(void) {
secp256k1_ge_t nums_ge;
VERIFY_CHECK(secp256k1_ge_set_xo(&nums_ge, &nums_x, 0));
secp256k1_gej_set_ge(&nums_gej, &nums_ge);
// Add G to make the bits in x uniformly distributed.
/* Add G to make the bits in x uniformly distributed. */
secp256k1_gej_add_ge_var(&nums_gej, &nums_gej, g);
}
// compute prec.
/* compute prec. */
secp256k1_ge_t prec[1024];
{
secp256k1_gej_t precj[1024]; // Jacobian versions of prec.
secp256k1_gej_t gbase; gbase = gj; // 16^j * G
secp256k1_gej_t numsbase; numsbase = nums_gej; // 2^j * nums.
secp256k1_gej_t precj[1024]; /* Jacobian versions of prec. */
secp256k1_gej_t gbase; gbase = gj; /* 16^j * G */
secp256k1_gej_t numsbase; numsbase = nums_gej; /* 2^j * nums. */
for (int j=0; j<64; j++) {
// Set precj[j*16 .. j*16+15] to (numsbase, numsbase + gbase, ..., numsbase + 15*gbase).
/* Set precj[j*16 .. j*16+15] to (numsbase, numsbase + gbase, ..., numsbase + 15*gbase). */
precj[j*16] = numsbase;
for (int i=1; i<16; i++) {
secp256k1_gej_add_var(&precj[j*16 + i], &precj[j*16 + i - 1], &gbase);
}
// Multiply gbase by 16.
/* Multiply gbase by 16. */
for (int i=0; i<4; i++) {
secp256k1_gej_double_var(&gbase, &gbase);
}
// Multiply numbase by 2.
/* Multiply numbase by 2. */
secp256k1_gej_double_var(&numsbase, &numsbase);
if (j == 62) {
// In the last iteration, numsbase is (1 - 2^j) * nums instead.
/* In the last iteration, numsbase is (1 - 2^j) * nums instead. */
secp256k1_gej_neg(&numsbase, &numsbase);
secp256k1_gej_add_var(&numsbase, &numsbase, &nums_gej);
}
@@ -85,7 +87,7 @@ static void secp256k1_ecmult_gen_start(void) {
}
}
// Set the global pointer to the precomputation table.
/* Set the global pointer to the precomputation table. */
secp256k1_ecmult_gen_consts = ret;
}