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bignum 256-bit and 512-bit

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NIIBE Yutaka
2011-10-10 22:32:49 +09:00
parent 2181c1a428
commit f936269eee
2 changed files with 264 additions and 0 deletions
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src/bn.c Normal file
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/*
* bn.c -- 256-bit and 512-bit bignum calculation
*
* Copyright (C) 2011 Free Software Initiative of Japan
* Author: NIIBE Yutaka <gniibe@fsij.org>
*
* This file is a part of Gnuk, a GnuPG USB Token implementation.
*
* Gnuk is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Gnuk is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
* License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdint.h>
#include "bn.h"
int
bn256_add (bn256 *X, const bn256 *A, const bn256 *B)
{
int i;
uint32_t carry = 0;
uint32_t *px;
const uint32_t *pa, *pb;
px = X->words;
pa = A->words;
pb = B->words;
for (i = 0; i < BN256_WORDS; i++)
{
*px = *pa + carry;
carry = (*px < carry);
*px += *pb;
carry += (*px < *pb);
px++;
pa++;
pb++;
}
return carry;
}
int
bn256_sub (bn256 *X, const bn256 *A, const bn256 *B)
{
int i;
uint32_t borrow = 0;
uint32_t *px;
const uint32_t *pa, *pb;
px = X->words;
pa = A->words;
pb = B->words;
for (i = 0; i < BN256_WORDS; i++)
{
uint32_t borrow0 = (*pa < borrow);
*px = *pa - borrow;
borrow = (*px < *pb) + borrow0;
*px -= *pb;
px++;
pa++;
pb++;
}
return borrow;
}
void
bn256_mul (bn512 *X, const bn256 *A, const bn256 *B)
{
int i, j, k;
int i_beg, i_end;
uint32_t r0, r1, r2;
r0 = r1 = r2 = 0;
for (k = 0; k <= (BN256_WORDS - 1)*2; k++)
{
if (k < BN256_WORDS)
{
i_beg = 0;
i_end = k;
}
else
{
i_beg = k - BN256_WORDS + 1;
i_end = BN256_WORDS - 1;
}
for (i = i_beg; i <= i_end; i++)
{
uint64_t uv;
uint32_t u, v;
uint32_t carry;
j = k - i;
uv = ((uint64_t )A->words[i])*((uint64_t )B->words[j]);
v = uv;
u = (uv >> 32);
r0 += v;
carry = (r0 < v);
r1 += carry;
carry = (r1 < carry);
r1 += u;
carry += (r1 < u);
r2 += carry;
}
X->words[k] = r0;
r0 = r1;
r1 = r2;
r2 = 0;
}
X->words[k] = r0;
}
void
bn256_sqr (bn512 *X, const bn256 *A)
{
int i, j, k;
int i_beg, i_end;
uint32_t r0, r1, r2;
r0 = r1 = r2 = 0;
for (k = 0; k <= (BN256_WORDS - 1)*2; k++)
{
if (k < BN256_WORDS)
{
i_beg = 0;
i_end = k/2;
}
else
{
i_beg = k - BN256_WORDS + 1;
i_end = k/2;
}
for (i = i_beg; i <= i_end; i++)
{
uint64_t uv;
uint32_t u, v;
uint32_t carry;
j = k - i;
uv = ((uint64_t )A->words[i])*((uint64_t )A->words[j]);
if (i < j)
{
if ((uv >> 63) != 0)
r2++;
uv <<= 1;
}
v = uv;
u = (uv >> 32);
r0 += v;
carry = (r0 < v);
r1 += carry;
carry = (r1 < carry);
r1 += u;
carry += (r1 < u);
r2 += carry;
}
X->words[k] = r0;
r0 = r1;
r1 = r2;
r2 = 0;
}
X->words[k] = r0;
}
int
bn256_shift (bn256 *X, const bn256 *A, int shift)
{
int i;
uint32_t carry = 0, next_carry;
if (shift > 0)
{
for (i = 0; i < BN256_WORDS; i++)
{
next_carry = A->words[i] >> (32 - shift);
X->words[i] = (A->words[i] << shift) | carry;
carry = next_carry;
}
}
else
{
shift = -shift;
for (i = BN256_WORDS - 1; i >= 0; i--)
{
next_carry = A->words[i] & ((1 << shift) - 1);
X->words[i] = (A->words[i] >> shift) | (carry << (32 - shift));
carry = next_carry;
}
}
return carry;
}
int
bn256_is_zero (const bn256 *X)
{
int i;
for (i = 0; i < BN256_WORDS; i++)
if (X->words[i] != 0)
return 0;
return 1;
}
int
bn256_is_even (const bn256 *X)
{
return !(X->words[0] & 1);
}
int
bn256_is_ge (const bn256 *A, const bn256 *B)
{
int i;
for (i = BN256_WORDS - 1; i >= 0; i--)
if (A->words[i] > B->words[i])
return 1;
else if (A->words[i] < B->words[i])
return 0;
return 1;
}

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#define BN256_WORDS 8
typedef struct bn256 {
uint32_t words[ BN256_WORDS ]; /* Little endian */
} bn256;
#define BN512_WORDS 16
typedef struct bn512 {
uint32_t words[ BN512_WORDS ]; /* Little endian */
} bn512;
int bn256_add (bn256 *X, const bn256 *A, const bn256 *B);
int bn256_sub (bn256 *X, const bn256 *A, const bn256 *B);
void bn256_mul (bn512 *X, const bn256 *A, const bn256 *B);
void bn256_sqr (bn512 *X, const bn256 *A);
int bn256_shift (bn256 *X, const bn256 *A, int shift);
int bn256_is_zero (const bn256 *X);
int bn256_is_even (const bn256 *X);
int bn256_is_ge (const bn256 *A, const bn256 *B);