diff options
Diffstat (limited to 'libtomcrypt/src/pk/ecc/ltc_ecc_projective_dbl_point.c')
| -rw-r--r-- | libtomcrypt/src/pk/ecc/ltc_ecc_projective_dbl_point.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/libtomcrypt/src/pk/ecc/ltc_ecc_projective_dbl_point.c b/libtomcrypt/src/pk/ecc/ltc_ecc_projective_dbl_point.c new file mode 100644 index 0000000..f0b3e1d --- /dev/null +++ b/libtomcrypt/src/pk/ecc/ltc_ecc_projective_dbl_point.c @@ -0,0 +1,147 @@ +/* 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 $ */ + |