Commit 6907bbac authored by Niels Möller's avatar Niels Möller

Implemented eddsa compression and decompression.

parent 993bfa0c
2014-10-02 Niels Möller <nisse@lysator.liu.se>
* eddsa-decompress.c (_eddsa_decompress): New file, new function.
* eddsa-compress.c (_eddsa_compress): New file, new function.
* eddsa.h: New file.
* Makefile.in (HEADERS): Added eddsa.h.
(hogweed_SOURCES): Added eddsa-compress.c and eddsa-decompress.c.
* testsuite/ecc-sqrt-test.c: New test case.
* testsuite/Makefile.in (TS_HOGWEED_SOURCES): Added
ecc-sqrt-test.c.
......
......@@ -176,13 +176,14 @@ hogweed_SOURCES = sexp.c sexp-format.c \
ecc-ecdsa-sign.c ecdsa-sign.c \
ecc-ecdsa-verify.c ecdsa-verify.c ecdsa-keygen.c \
curve25519-mul-g.c curve25519-mul.c curve25519-eh-to-x.c \
eddsa-compress.c eddsa-decompress.c \
$(OPT_HOGWEED_SOURCES)
HEADERS = aes.h arcfour.h arctwo.h asn1.h blowfish.h \
base16.h base64.h buffer.h camellia.h cast128.h \
cbc.h ccm.h chacha.h chacha-poly1305.h ctr.h \
curve25519.h des.h des-compat.h dsa.h dsa-compat.h eax.h \
ecc-curve.h ecc.h ecdsa.h \
ecc-curve.h ecc.h ecdsa.h eddsa.h \
gcm.h gosthash94.h hmac.h \
knuth-lfib.h \
macros.h \
......
/* eddsa-compress.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 "eddsa.h"
#include "ecc-internal.h"
#include "gmp-glue.h"
mp_size_t
_eddsa_compress_itch (const struct ecc_curve *ecc)
{
return 2*ecc->p.size + ecc->h_to_a_itch;
}
void
_eddsa_compress (const struct ecc_curve *ecc, uint8_t *r, mp_limb_t *p,
mp_limb_t *scratch)
{
#define xp scratch
#define yp (scratch + ecc->p.size)
#define scratch_out (scratch + 2*ecc->p.size)
ecc->h_to_a (ecc, 0, xp, p, scratch_out);
/* Encoding is the y coordinate and an appended "sign" bit, which is
the low bit of x. Bit order is not specified explicitly, but for
little-endian encoding, it makes most sense to append the bit
after the most significant bit of y. */
mpn_get_base256_le (r, 1 + ecc->p.bit_size / 8, yp, ecc->p.size);
r[ecc->p.bit_size / 8] += (xp[0] & 1) << (ecc->p.bit_size & 7);
}
/* eddsa-decompress.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 "eddsa.h"
#include "ecc-internal.h"
#include "gmp-glue.h"
mp_size_t
_eddsa_decompress_itch (const struct ecc_curve *ecc)
{
return 4*ecc->p.size + ecc->p.sqrt_itch;
}
int
_eddsa_decompress (const struct ecc_curve *ecc, mp_limb_t *p,
const uint8_t *cp,
mp_limb_t *scratch)
{
mp_limb_t sign, cy;
int res;
#define xp p
#define yp (p + ecc->p.size)
#define y2 scratch
#define vp (scratch + ecc->p.size)
#define up scratch
#define tp (scratch + 2*ecc->p.size)
#define scratch_out (scratch + 4*ecc->p.size)
sign = cp[ecc->p.bit_size / 8] >> (ecc->p.bit_size & 7);
if (sign > 1)
return 0;
mpn_set_base256_le (yp, ecc->p.size, cp, 1 + ecc->p.bit_size / 8);
/* Clear out the sign bit (if it fits) */
yp[ecc->p.size - 1] &= ~(mp_limb_t) 0
>> (ecc->p.size * GMP_NUMB_BITS - ecc->p.bit_size);
ecc_modp_sqr (ecc, y2, yp);
ecc_modp_mul (ecc, vp, y2, ecc->b);
ecc_modp_sub (ecc, vp, vp, ecc->unit);
ecc_modp_sub (ecc, up, ecc->unit, y2);
res = ecc->p.sqrt (&ecc->p, tp, up, vp, scratch_out);
cy = mpn_sub_n (xp, tp, ecc->p.m, ecc->p.size);
cnd_copy (cy, xp, tp, ecc->p.size);
sign ^= xp[0] & 1;
mpn_sub_n (tp, ecc->p.m, xp, ecc->p.size);
cnd_copy (sign, xp, tp, ecc->p.size);
return res;
}
/* eddsa.h
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/.
*/
#ifndef NETTLE_EDDSA_H
#define NETTLE_EDDSA_H
#include "nettle-types.h"
#include "bignum.h"
#ifdef __cplusplus
extern "C" {
#endif
/* Name mangling */
#define _eddsa_compress _nettle_eddsa_compress
#define _eddsa_compress_itch _nettle_eddsa_compress_itch
#define _eddsa_decompress _nettle_eddsa_decompress
#define _eddsa_decompress_itch _nettle_eddsa_decompress_itch
#define ED25519_KEY_SIZE 32
struct ecc_curve;
mp_size_t
_eddsa_compress_itch (const struct ecc_curve *ecc);
void
_eddsa_compress (const struct ecc_curve *ecc, uint8_t *r, mp_limb_t *p,
mp_limb_t *scratch);
mp_size_t
_eddsa_decompress_itch (const struct ecc_curve *ecc);
int
_eddsa_decompress (const struct ecc_curve *ecc, mp_limb_t *p,
const uint8_t *cp,
mp_limb_t *scratch);
#ifdef __cplusplus
}
#endif
#endif /* NETTLE_EDDSA_H */
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