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add fe25519

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NIIBE Yutaka
2014-01-20 16:13:15 +09:00
parent 38f8b91335
commit 4f154cc61d
3 changed files with 142 additions and 0 deletions
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src/fe25519.c Normal file
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/*
* fe25519.c -- 2^255-19 field element computation
*
* Copyright (C) 2014 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/>.
*
*/
/*
* The field is \Z/(2^255-19)
*
* We use radix-32. During computation, it's not reduced to 2^255-19,
* but it is represented in 256-bit (it is redundant representation).
*/
#include <stdint.h>
#include <string.h>
#include "fe25519.h"
#define ADDWORD_256(d_,w_,c_) \
asm ( "ldmia %[d], { r4, r5, r6, r7 } \n\t" \
"adds r4, r4, %[w] \n\t" \
"adcs r5, r5, #0 \n\t" \
"adcs r6, r6, #0 \n\t" \
"adcs r7, r7, #0 \n\t" \
"stmia %[d]!, { r4, r5, r6, r7 }\n\t" \
"ldmia %[d], { r4, r5, r6, r7 } \n\t" \
"adcs r4, r4, #0 \n\t" \
"adcs r5, r5, #0 \n\t" \
"adcs r6, r6, #0 \n\t" \
"adcs r7, r7, #0 \n\t" \
"stmia %[d]!, { r4, r5, r6, r7 }\n\t" \
"mov %[c], #0 \n\t" \
"adc %[c], %[c], #0" \
: [d] "=&r" (d_), [c] "=&r" (c_) \
: "[d]" (d_), [w] "r" (w_) \
: "r4", "r5", "r6", "r7", "memory", "cc" )
#define MULADD_256(s_,d_,w_,c_) do { \
asm ( "ldmia %[s]!, { r8, r9, r10 } \n\t" \
"ldmia %[d], { r5, r6, r7 } \n\t" \
"umull r4, r8, %[w], r8 \n\t" \
"adds r5, r5, r4 \n\t" \
"adcs r6, r6, r8 \n\t" \
"umull r4, r8, %[w], r9 \n\t" \
"adc %[c], r8, #0 \n\t" \
"adds r6, r6, r4 \n\t" \
"adcs r7, r7, %[c] \n\t" \
"umull r4, r8, %[w], r10 \n\t" \
"adc %[c], r8, #0 \n\t" \
"adds r7, r7, r4 \n\t" \
"stmia %[d]!, { r5, r6, r7 } \n\t" \
"ldmia %[s]!, { r8, r9, r10 } \n\t" \
"ldmia %[d], { r5, r6, r7 } \n\t" \
"adcs r5, r5, %[c] \n\t" \
"umull r4, r8, %[w], r8 \n\t" \
"adc %[c], r8, #0 \n\t" \
"adds r5, r5, r4 \n\t" \
"adcs r6, r6, %[c] \n\t" \
"umull r4, r8, %[w], r9 \n\t" \
"adc %[c], r8, #0 \n\t" \
"adds r6, r6, r4 \n\t" \
"adcs r7, r7, %[c] \n\t" \
"umull r4, r8, %[w], r10 \n\t" \
"adc %[c], r8, #0 \n\t" \
"adds r7, r7, r4 \n\t" \
"stmia %[d]!, { r5, r6, r7 } \n\t" \
"ldmia %[s]!, { r8, r9 } \n\t" \
"ldmia %[d], { r5, r6 } \n\t" \
"adcs r5, r5, %[c] \n\t" \
"umull r4, r8, %[w], r8 \n\t" \
"adc %[c], r8, #0 \n\t" \
"adds r5, r5, r4 \n\t" \
"adcs r6, r6, %[c] \n\t" \
"umull r4, r8, %[w], r9 \n\t" \
"adc %[c], r8, #0 \n\t" \
"adds r6, r6, r4 \n\t" \
"adc %[c], %[c], #0 \n\t" \
"stmia %[d]!, { r5, r6 }" \
: [s] "=&r" (s_), [d] "=&r" (d_), [c] "=&r" (c_) \
: "[s]" (s_), "[d]" (d_), [w] "r" (w_) \
: "r4", "r5", "r6", "r7", "r8", "r9", "r10", \
"memory", "cc" ); \
*d_ = c_; \
} while (0)
static void mul_hlp (const uint32_t *s, uint32_t *d, uint32_t w)
{
uint32_t c;
MULADD_256 (s, d, w, c);
}
void fe_mul (fe25519 *X, const fe25519 *A, const fe25519 *B)
{
uint32_t word[FE25519_WORDS*2];
const uint32_t *s;
uint32_t *d;
uint32_t w;
uint32_t c, c0;
memset (word, 0, sizeof (uint32_t)*FE25519_WORDS);
s = A->word; d = &word[0]; w = B->word[0]; MULADD_256 (s, d, w, c);
s = A->word; d = &word[1]; w = B->word[1]; MULADD_256 (s, d, w, c);
s = A->word; d = &word[2]; w = B->word[2]; MULADD_256 (s, d, w, c);
s = A->word; d = &word[3]; w = B->word[3]; MULADD_256 (s, d, w, c);
s = A->word; d = &word[4]; w = B->word[4]; MULADD_256 (s, d, w, c);
s = A->word; d = &word[5]; w = B->word[5]; MULADD_256 (s, d, w, c);
s = A->word; d = &word[6]; w = B->word[6]; MULADD_256 (s, d, w, c);
s = A->word; d = &word[7]; w = B->word[7]; MULADD_256 (s, d, w, c);
s = &word[8]; d = &word[0]; w = 38; MULADD_256 (s, d, w, c);
c0 = word[8] * 38;
s = word;
ADDWORD_256 (s, c0, c);
word[0] += c * 38;
memcpy (X->word, word, sizeof X->word);
}

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src/fe25519.h Normal file
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#define FE25519_WORDS 8
typedef struct fe25519 {
uint32_t word[FE25519_WORDS]; /* Little endian */
} fe25519;