Commit e741c938 authored by Niels Möller's avatar Niels Möller

Implemented curve25519_mul.

parent 6c8d40f7
2014-08-18 Niels Möller <nisse@lysator.liu.se> 2014-08-18 Niels Möller <nisse@lysator.liu.se>
* curve25519-mul.c (curve25519_mul): New file and function.
* curve25519.h (curve25519_mul): Declare it.
* Makefile.in (hogweed_SOURCES): Added curve25519-mul.c.
* curve25519-mul-g.c (curve25519_mul_g): Renamed file and * curve25519-mul-g.c (curve25519_mul_g): Renamed file and
function, updated callers. function, updated callers.
* curve25519-base.c (curve25519_base): ... old names. * curve25519-base.c (curve25519_base): ... old names.
......
...@@ -174,7 +174,7 @@ hogweed_SOURCES = sexp.c sexp-format.c \ ...@@ -174,7 +174,7 @@ hogweed_SOURCES = sexp.c sexp-format.c \
ecc-point.c ecc-scalar.c ecc-point-mul.c ecc-point-mul-g.c \ ecc-point.c ecc-scalar.c ecc-point-mul.c ecc-point-mul-g.c \
ecc-ecdsa-sign.c ecdsa-sign.c \ ecc-ecdsa-sign.c ecdsa-sign.c \
ecc-ecdsa-verify.c ecdsa-verify.c ecdsa-keygen.c \ ecc-ecdsa-verify.c ecdsa-verify.c ecdsa-keygen.c \
curve25519-mul-g.c \ curve25519-mul-g.c curve25519-mul.c \
$(OPT_HOGWEED_SOURCES) $(OPT_HOGWEED_SOURCES)
HEADERS = aes.h arcfour.h arctwo.h asn1.h blowfish.h \ HEADERS = aes.h arcfour.h arctwo.h asn1.h blowfish.h \
......
/* curve25519-mul.c
Copyright (C) 2014 Niels Möller
This file is part of GNU Nettle.
GNU Nettle is free software: you can redistribute it and/or
modify it under the terms of either:
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
or
* the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.
or both in parallel, as here.
GNU Nettle 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 copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see http://www.gnu.org/licenses/.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <string.h>
#include "curve25519.h"
#include "ecc.h"
#include "ecc-internal.h"
/* Intended to be compatible with NaCl's crypto_scalarmult. NOTE: Not
side-channel silent, due to the sqrt. */
int
curve25519_mul (uint8_t *q, const uint8_t *n, const uint8_t *p)
{
uint8_t t[CURVE25519_SIZE];
mp_size_t itch;
mp_limb_t *scratch;
const struct ecc_curve *ecc = &nettle_curve25519;
#define x scratch
#define y (scratch + ecc->size)
#define s (scratch + 3*ecc->size)
#define scratch_out (scratch + 4*ecc->size)
itch = 5*ecc->size + ECC_MUL_A_EH_ITCH (ecc->size);
scratch = gmp_alloc_limbs (itch);
mpn_set_base256_le (x, ecc->size, p, CURVE25519_SIZE);
/* First compute y coordinate, from
y^2 = x^3 + b x^2 + x = (x^2 + bx + 1) x
*/
ecc_modp_sqr (&nettle_curve25519, y, x);
ecc_modp_addmul_1 (&nettle_curve25519, y, x, 0x76d06ULL);
ecc_modp_add (ecc, s, y, ecc->unit);
ecc_modp_mul (ecc, y, s, x);
/* FIXME: Pass s as scratch space to ecc_25519_sqrt */
if (!ecc_25519_sqrt (y, y))
/* y-coordinate doesn't belong to base field F_p. FIXME: Implement
case of y in F_{p^2}? */
return 0;
memcpy (t, n, sizeof(t));
t[0] &= ~7;
t[CURVE25519_SIZE-1] = (t[CURVE25519_SIZE-1] & 0x3f) | 0x40;
mpn_set_base256_le (s, ecc->size, t, CURVE25519_SIZE);
ecc_mul_a_eh (ecc, x, s, x, scratch_out);
ecc_eh_to_a (ecc, 2, s, x, scratch_out);
mpn_get_base256_le (q, CURVE25519_SIZE, s, ecc->size);
gmp_free_limbs (scratch, itch);
return 1;
}
...@@ -40,10 +40,14 @@ extern "C" { ...@@ -40,10 +40,14 @@ extern "C" {
/* Name mangling */ /* Name mangling */
#define curve25519_mul_g nettle_curve25519_mul_g #define curve25519_mul_g nettle_curve25519_mul_g
#define curve25519_mul nettle_curve25519_mul
#define CURVE25519_SIZE 32 #define CURVE25519_SIZE 32
void void
curve25519_mul_g (uint8_t *q, const uint8_t *n); curve25519_mul_g (uint8_t *q, const uint8_t *n);
int
curve25519_mul (uint8_t *q, const uint8_t *n, const uint8_t *p);
#endif /* NETTLE_CURVE25519_H */ #endif /* NETTLE_CURVE25519_H */
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment