1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* LibTomCrypt, modular cryptographic library -- Tom St Denis 2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 3f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * LibTomCrypt is a library that provides various cryptographic 4f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * algorithms in a highly modular and flexible manner. 5f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 6f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * The library is free for all purposes without any express 7f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * guarantee it works. 8f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 9f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com 10f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project */ 11f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 12f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b 13f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 14f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * All curves taken from NIST recommendation paper of July 1999 15f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Available at http://csrc.nist.gov/cryptval/dss.htm 16f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project */ 17f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include "tomcrypt.h" 18f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @file ltc_ecc_map.c 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ECC Crypto, Tom St Denis 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef MECC 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project Map a projective jacbobian point back to affine space 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param P [in/out] The point to map 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param modulus The modulus of the field the ECC curve is in 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param mp The "b" value from montgomery_setup() 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @return CRYPT_OK on success 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint ltc_ecc_map(ecc_point *P, void *modulus, void *mp) 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project void *t1, *t2; 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int err; 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(P != NULL); 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(modulus != NULL); 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(mp != NULL); 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_init_multi(&t1, &t2, NULL)) != CRYPT_OK) { 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return CRYPT_MEM; 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* first map z back to normal */ 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(P->z, modulus, mp)) != CRYPT_OK) { goto done; } 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* get 1/z */ 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_invmod(P->z, modulus, t1)) != CRYPT_OK) { goto done; } 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* get 1/z^2 and 1/z^3 */ 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sqr(t1, t2)) != CRYPT_OK) { goto done; } 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mod(t2, modulus, t2)) != CRYPT_OK) { goto done; } 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(t1, t2, t1)) != CRYPT_OK) { goto done; } 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mod(t1, modulus, t1)) != CRYPT_OK) { goto done; } 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* multiply against x/y */ 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(P->x, t2, P->x)) != CRYPT_OK) { goto done; } 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(P->x, modulus, mp)) != CRYPT_OK) { goto done; } 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(P->y, t1, P->y)) != CRYPT_OK) { goto done; } 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(P->y, modulus, mp)) != CRYPT_OK) { goto done; } 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_set(P->z, 1)) != CRYPT_OK) { goto done; } 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project err = CRYPT_OK; 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectdone: 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_clear_multi(t1, t2, NULL); 68f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 69f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 70f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 71f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 72f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 73f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_map.c,v $ */ 74f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.5 $ */ 75f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/12/04 02:50:11 $ */ 76f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 77