Mercurial > dropbear
comparison src/pk/ecc/ltc_ecc_map.c @ 380:d5faf4814ddb libtomcrypt-orig libtomcrypt-1.16
Update to LibTomCrypt 1.16
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Thu, 11 Jan 2007 02:22:00 +0000 |
| parents | |
| children |
comparison
equal
deleted
inserted
replaced
| 280:59400faa4b44 | 380:d5faf4814ddb |
|---|---|
| 1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis | |
| 2 * | |
| 3 * LibTomCrypt is a library that provides various cryptographic | |
| 4 * algorithms in a highly modular and flexible manner. | |
| 5 * | |
| 6 * The library is free for all purposes without any express | |
| 7 * guarantee it works. | |
| 8 * | |
| 9 * Tom St Denis, [email protected], http://libtomcrypt.com | |
| 10 */ | |
| 11 | |
| 12 /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b | |
| 13 * | |
| 14 * All curves taken from NIST recommendation paper of July 1999 | |
| 15 * Available at http://csrc.nist.gov/cryptval/dss.htm | |
| 16 */ | |
| 17 #include "tomcrypt.h" | |
| 18 | |
| 19 /** | |
| 20 @file ltc_ecc_map.c | |
| 21 ECC Crypto, Tom St Denis | |
| 22 */ | |
| 23 | |
| 24 #ifdef MECC | |
| 25 | |
| 26 /** | |
| 27 Map a projective jacbobian point back to affine space | |
| 28 @param P [in/out] The point to map | |
| 29 @param modulus The modulus of the field the ECC curve is in | |
| 30 @param mp The "b" value from montgomery_setup() | |
| 31 @return CRYPT_OK on success | |
| 32 */ | |
| 33 int ltc_ecc_map(ecc_point *P, void *modulus, void *mp) | |
| 34 { | |
| 35 void *t1, *t2; | |
| 36 int err; | |
| 37 | |
| 38 LTC_ARGCHK(P != NULL); | |
| 39 LTC_ARGCHK(modulus != NULL); | |
| 40 LTC_ARGCHK(mp != NULL); | |
| 41 | |
| 42 if ((err = mp_init_multi(&t1, &t2, NULL)) != CRYPT_OK) { | |
| 43 return CRYPT_MEM; | |
| 44 } | |
| 45 | |
| 46 /* first map z back to normal */ | |
| 47 if ((err = mp_montgomery_reduce(P->z, modulus, mp)) != CRYPT_OK) { goto done; } | |
| 48 | |
| 49 /* get 1/z */ | |
| 50 if ((err = mp_invmod(P->z, modulus, t1)) != CRYPT_OK) { goto done; } | |
| 51 | |
| 52 /* get 1/z^2 and 1/z^3 */ | |
| 53 if ((err = mp_sqr(t1, t2)) != CRYPT_OK) { goto done; } | |
| 54 if ((err = mp_mod(t2, modulus, t2)) != CRYPT_OK) { goto done; } | |
| 55 if ((err = mp_mul(t1, t2, t1)) != CRYPT_OK) { goto done; } | |
| 56 if ((err = mp_mod(t1, modulus, t1)) != CRYPT_OK) { goto done; } | |
| 57 | |
| 58 /* multiply against x/y */ | |
| 59 if ((err = mp_mul(P->x, t2, P->x)) != CRYPT_OK) { goto done; } | |
| 60 if ((err = mp_montgomery_reduce(P->x, modulus, mp)) != CRYPT_OK) { goto done; } | |
| 61 if ((err = mp_mul(P->y, t1, P->y)) != CRYPT_OK) { goto done; } | |
| 62 if ((err = mp_montgomery_reduce(P->y, modulus, mp)) != CRYPT_OK) { goto done; } | |
| 63 if ((err = mp_set(P->z, 1)) != CRYPT_OK) { goto done; } | |
| 64 | |
| 65 err = CRYPT_OK; | |
| 66 done: | |
| 67 mp_clear_multi(t1, t2, NULL); | |
| 68 return err; | |
| 69 } | |
| 70 | |
| 71 #endif | |
| 72 | |
| 73 /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_map.c,v $ */ | |
| 74 /* $Revision: 1.5 $ */ | |
| 75 /* $Date: 2006/12/04 02:50:11 $ */ | |
| 76 |