?? ltc_ecc_projective_dbl_point.c
字號:
/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com *//* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b * * All curves taken from NIST recommendation paper of July 1999 * Available at http://csrc.nist.gov/cryptval/dss.htm */#include "tomcrypt.h"/** @file ltc_ecc_projective_dbl_point.c ECC Crypto, Tom St Denis*/ #if defined(MECC) && (!defined(MECC_ACCEL) || defined(LTM_DESC))/** Double an ECC point @param P The point to double @param R [out] The destination of the double @param modulus The modulus of the field the ECC curve is in @param mp The "b" value from montgomery_setup() @return CRYPT_OK on success*/int ltc_ecc_projective_dbl_point(ecc_point *P, ecc_point *R, void *modulus, void *mp){ void *t1, *t2; int err; LTC_ARGCHK(P != NULL); LTC_ARGCHK(R != NULL); LTC_ARGCHK(modulus != NULL); LTC_ARGCHK(mp != NULL); if ((err = mp_init_multi(&t1, &t2, NULL)) != CRYPT_OK) { return err; } if (P != R) { if ((err = mp_copy(P->x, R->x)) != CRYPT_OK) { goto done; } if ((err = mp_copy(P->y, R->y)) != CRYPT_OK) { goto done; } if ((err = mp_copy(P->z, R->z)) != CRYPT_OK) { goto done; } } /* t1 = Z * Z */ if ((err = mp_sqr(R->z, t1)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } /* Z = Y * Z */ if ((err = mp_mul(R->z, R->y, R->z)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(R->z, modulus, mp)) != CRYPT_OK) { goto done; } /* Z = 2Z */ if ((err = mp_add(R->z, R->z, R->z)) != CRYPT_OK) { goto done; } if (mp_cmp(R->z, modulus) != LTC_MP_LT) { if ((err = mp_sub(R->z, modulus, R->z)) != CRYPT_OK) { goto done; } } /* T2 = X - T1 */ if ((err = mp_sub(R->x, t1, t2)) != CRYPT_OK) { goto done; } if (mp_cmp_d(t2, 0) == LTC_MP_LT) { if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK) { goto done; } } /* T1 = X + T1 */ if ((err = mp_add(t1, R->x, t1)) != CRYPT_OK) { goto done; } if (mp_cmp(t1, modulus) != LTC_MP_LT) { if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK) { goto done; } } /* T2 = T1 * T2 */ if ((err = mp_mul(t1, t2, t2)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } /* T1 = 2T2 */ if ((err = mp_add(t2, t2, t1)) != CRYPT_OK) { goto done; } if (mp_cmp(t1, modulus) != LTC_MP_LT) { if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK) { goto done; } } /* T1 = T1 + T2 */ if ((err = mp_add(t1, t2, t1)) != CRYPT_OK) { goto done; } if (mp_cmp(t1, modulus) != LTC_MP_LT) { if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK) { goto done; } } /* Y = 2Y */ if ((err = mp_add(R->y, R->y, R->y)) != CRYPT_OK) { goto done; } if (mp_cmp(R->y, modulus) != LTC_MP_LT) { if ((err = mp_sub(R->y, modulus, R->y)) != CRYPT_OK) { goto done; } } /* Y = Y * Y */ if ((err = mp_sqr(R->y, R->y)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(R->y, modulus, mp)) != CRYPT_OK) { goto done; } /* T2 = Y * Y */ if ((err = mp_sqr(R->y, t2)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } /* T2 = T2/2 */ if (mp_isodd(t2)) { if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK) { goto done; } } if ((err = mp_div_2(t2, t2)) != CRYPT_OK) { goto done; } /* Y = Y * X */ if ((err = mp_mul(R->y, R->x, R->y)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(R->y, modulus, mp)) != CRYPT_OK) { goto done; } /* X = T1 * T1 */ if ((err = mp_sqr(t1, R->x)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(R->x, modulus, mp)) != CRYPT_OK) { goto done; } /* X = X - Y */ if ((err = mp_sub(R->x, R->y, R->x)) != CRYPT_OK) { goto done; } if (mp_cmp_d(R->x, 0) == LTC_MP_LT) { if ((err = mp_add(R->x, modulus, R->x)) != CRYPT_OK) { goto done; } } /* X = X - Y */ if ((err = mp_sub(R->x, R->y, R->x)) != CRYPT_OK) { goto done; } if (mp_cmp_d(R->x, 0) == LTC_MP_LT) { if ((err = mp_add(R->x, modulus, R->x)) != CRYPT_OK) { goto done; } } /* Y = Y - X */ if ((err = mp_sub(R->y, R->x, R->y)) != CRYPT_OK) { goto done; } if (mp_cmp_d(R->y, 0) == LTC_MP_LT) { if ((err = mp_add(R->y, modulus, R->y)) != CRYPT_OK) { goto done; } } /* Y = Y * T1 */ if ((err = mp_mul(R->y, t1, R->y)) != CRYPT_OK) { goto done; } if ((err = mp_montgomery_reduce(R->y, modulus, mp)) != CRYPT_OK) { goto done; } /* Y = Y - T2 */ if ((err = mp_sub(R->y, t2, R->y)) != CRYPT_OK) { goto done; } if (mp_cmp_d(R->y, 0) == LTC_MP_LT) { if ((err = mp_add(R->y, modulus, R->y)) != CRYPT_OK) { goto done; } } err = CRYPT_OK;done: mp_clear_multi(t1, t2, NULL); return err;}#endif/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_projective_dbl_point.c,v $ *//* $Revision: 1.8 $ *//* $Date: 2006/12/04 05:07:59 $ */?? 快捷鍵說明
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