diff options
Diffstat (limited to 'src/pk/ecc/ltc_ecc_projective_add_point.c')
| -rw-r--r-- | src/pk/ecc/ltc_ecc_projective_add_point.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/src/pk/ecc/ltc_ecc_projective_add_point.c b/src/pk/ecc/ltc_ecc_projective_add_point.c new file mode 100644 index 0000000..c8e359f --- /dev/null +++ b/src/pk/ecc/ltc_ecc_projective_add_point.c @@ -0,0 +1,196 @@ +/* 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_add_point.c + ECC Crypto, Tom St Denis +*/ + +#if defined(MECC) && (!defined(MECC_ACCEL) || defined(LTM_DESC)) + +/** + Add two ECC points + @param P The point to add + @param Q The point to add + @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_add_point(ecc_point *P, ecc_point *Q, ecc_point *R, void *modulus, void *mp) +{ + void *t1, *t2, *x, *y, *z; + int err; + + LTC_ARGCHK(P != NULL); + LTC_ARGCHK(Q != NULL); + LTC_ARGCHK(R != NULL); + LTC_ARGCHK(modulus != NULL); + LTC_ARGCHK(mp != NULL); + + if ((err = mp_init_multi(&t1, &t2, &x, &y, &z, NULL)) != CRYPT_OK) { + return err; + } + + /* should we dbl instead? */ + if ((err = mp_sub(modulus, Q->y, t1)) != CRYPT_OK) { goto done; } + + if ( (mp_cmp(P->x, Q->x) == LTC_MP_EQ) && + (Q->z != NULL && mp_cmp(P->z, Q->z) == LTC_MP_EQ) && + (mp_cmp(P->y, Q->y) == LTC_MP_EQ || mp_cmp(P->y, t1) == LTC_MP_EQ)) { + mp_clear_multi(t1, t2, x, y, z, NULL); + return ltc_ecc_projective_dbl_point(P, R, modulus, mp); + } + + if ((err = mp_copy(P->x, x)) != CRYPT_OK) { goto done; } + if ((err = mp_copy(P->y, y)) != CRYPT_OK) { goto done; } + if ((err = mp_copy(P->z, z)) != CRYPT_OK) { goto done; } + + /* if Z is one then these are no-operations */ + if (Q->z != NULL) { + /* T1 = Z' * Z' */ + if ((err = mp_sqr(Q->z, t1)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } + /* X = X * T1 */ + if ((err = mp_mul(t1, x, x)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK) { goto done; } + /* T1 = Z' * T1 */ + if ((err = mp_mul(Q->z, t1, t1)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } + /* Y = Y * T1 */ + if ((err = mp_mul(t1, y, y)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(y, modulus, mp)) != CRYPT_OK) { goto done; } + } + + /* T1 = Z*Z */ + if ((err = mp_sqr(z, t1)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } + /* T2 = X' * T1 */ + if ((err = mp_mul(Q->x, t1, t2)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } + /* T1 = Z * T1 */ + if ((err = mp_mul(z, t1, t1)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } + /* T1 = Y' * T1 */ + if ((err = mp_mul(Q->y, t1, t1)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } + + /* Y = Y - T1 */ + if ((err = mp_sub(y, t1, y)) != CRYPT_OK) { goto done; } + if (mp_cmp_d(y, 0) == LTC_MP_LT) { + if ((err = mp_add(y, modulus, y)) != CRYPT_OK) { goto done; } + } + /* T1 = 2T1 */ + if ((err = mp_add(t1, t1, 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 = Y + T1 */ + if ((err = mp_add(t1, y, t1)) != CRYPT_OK) { goto done; } + if (mp_cmp(t1, modulus) != LTC_MP_LT) { + if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK) { goto done; } + } + /* X = X - T2 */ + if ((err = mp_sub(x, t2, x)) != CRYPT_OK) { goto done; } + if (mp_cmp_d(x, 0) == LTC_MP_LT) { + if ((err = mp_add(x, modulus, x)) != CRYPT_OK) { goto done; } + } + /* T2 = 2T2 */ + if ((err = mp_add(t2, t2, t2)) != CRYPT_OK) { goto done; } + if (mp_cmp(t2, modulus) != LTC_MP_LT) { + if ((err = mp_sub(t2, modulus, t2)) != CRYPT_OK) { goto done; } + } + /* T2 = X + T2 */ + if ((err = mp_add(t2, x, t2)) != CRYPT_OK) { goto done; } + if (mp_cmp(t2, modulus) != LTC_MP_LT) { + if ((err = mp_sub(t2, modulus, t2)) != CRYPT_OK) { goto done; } + } + + /* if Z' != 1 */ + if (Q->z != NULL) { + /* Z = Z * Z' */ + if ((err = mp_mul(z, Q->z, z)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(z, modulus, mp)) != CRYPT_OK) { goto done; } + } + + /* Z = Z * X */ + if ((err = mp_mul(z, x, z)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(z, modulus, mp)) != CRYPT_OK) { goto done; } + + /* T1 = T1 * X */ + if ((err = mp_mul(t1, x, t1)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } + /* X = X * X */ + if ((err = mp_sqr(x, x)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK) { goto done; } + /* T2 = T2 * x */ + if ((err = mp_mul(t2, x, t2)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } + /* T1 = T1 * X */ + if ((err = mp_mul(t1, x, t1)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } + + /* X = Y*Y */ + if ((err = mp_sqr(y, x)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK) { goto done; } + /* X = X - T2 */ + if ((err = mp_sub(x, t2, x)) != CRYPT_OK) { goto done; } + if (mp_cmp_d(x, 0) == LTC_MP_LT) { + if ((err = mp_add(x, modulus, x)) != CRYPT_OK) { goto done; } + } + + /* T2 = T2 - X */ + if ((err = mp_sub(t2, x, 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; } + } + /* T2 = T2 - X */ + if ((err = mp_sub(t2, x, 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; } + } + /* T2 = T2 * Y */ + if ((err = mp_mul(t2, y, t2)) != CRYPT_OK) { goto done; } + if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } + /* Y = T2 - T1 */ + if ((err = mp_sub(t2, t1, y)) != CRYPT_OK) { goto done; } + if (mp_cmp_d(y, 0) == LTC_MP_LT) { + if ((err = mp_add(y, modulus, y)) != CRYPT_OK) { goto done; } + } + /* Y = Y/2 */ + if (mp_isodd(y)) { + if ((err = mp_add(y, modulus, y)) != CRYPT_OK) { goto done; } + } + if ((err = mp_div_2(y, y)) != CRYPT_OK) { goto done; } + + if ((err = mp_copy(x, R->x)) != CRYPT_OK) { goto done; } + if ((err = mp_copy(y, R->y)) != CRYPT_OK) { goto done; } + if ((err = mp_copy(z, R->z)) != CRYPT_OK) { goto done; } + + err = CRYPT_OK; +done: + mp_clear_multi(t1, t2, x, y, z, NULL); + return err; +} + +#endif + +/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_projective_add_point.c,v $ */ +/* $Revision: 1.13 $ */ +/* $Date: 2006/12/04 05:07:59 $ */ + |