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_projective_add_point.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#if defined(MECC) && (!defined(MECC_ACCEL) || defined(LTM_DESC)) 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project Add two ECC points 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param P The point to add 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param Q The point to add 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param R [out] The destination of the double 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param modulus The modulus of the field the ECC curve is in 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param mp The "b" value from montgomery_setup() 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @return CRYPT_OK on success 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint ltc_ecc_projective_add_point(ecc_point *P, ecc_point *Q, ecc_point *R, void *modulus, void *mp) 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project void *t1, *t2, *x, *y, *z; 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int err; 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(P != NULL); 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(Q != NULL); 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(R != NULL); 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(modulus != NULL); 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(mp != NULL); 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_init_multi(&t1, &t2, &x, &y, &z, NULL)) != CRYPT_OK) { 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* should we dbl instead? */ 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(modulus, Q->y, t1)) != CRYPT_OK) { goto done; } 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ( (mp_cmp(P->x, Q->x) == LTC_MP_EQ) && 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project (Q->z != NULL && mp_cmp(P->z, Q->z) == LTC_MP_EQ) && 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project (mp_cmp(P->y, Q->y) == LTC_MP_EQ || mp_cmp(P->y, t1) == LTC_MP_EQ)) { 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_clear_multi(t1, t2, x, y, z, NULL); 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return ltc_ecc_projective_dbl_point(P, R, modulus, mp); 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_copy(P->x, x)) != CRYPT_OK) { goto done; } 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_copy(P->y, y)) != CRYPT_OK) { goto done; } 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_copy(P->z, z)) != CRYPT_OK) { goto done; } 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* if Z is one then these are no-operations */ 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (Q->z != NULL) { 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = Z' * Z' */ 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sqr(Q->z, t1)) != CRYPT_OK) { goto done; } 68f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } 69f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* X = X * T1 */ 70f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(t1, x, x)) != CRYPT_OK) { goto done; } 71f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK) { goto done; } 72f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = Z' * T1 */ 73f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(Q->z, t1, t1)) != CRYPT_OK) { goto done; } 74f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } 75f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* Y = Y * T1 */ 76f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(t1, y, y)) != CRYPT_OK) { goto done; } 77f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(y, modulus, mp)) != CRYPT_OK) { goto done; } 78f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 79f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 80f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = Z*Z */ 81f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sqr(z, t1)) != CRYPT_OK) { goto done; } 82f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } 83f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T2 = X' * T1 */ 84f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(Q->x, t1, t2)) != CRYPT_OK) { goto done; } 85f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } 86f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = Z * T1 */ 87f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(z, t1, t1)) != CRYPT_OK) { goto done; } 88f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } 89f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = Y' * T1 */ 90f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(Q->y, t1, t1)) != CRYPT_OK) { goto done; } 91f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } 92f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 93f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* Y = Y - T1 */ 94f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(y, t1, y)) != CRYPT_OK) { goto done; } 95f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp_d(y, 0) == LTC_MP_LT) { 96f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(y, modulus, y)) != CRYPT_OK) { goto done; } 97f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 98f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = 2T1 */ 99f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(t1, t1, t1)) != CRYPT_OK) { goto done; } 100f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp(t1, modulus) != LTC_MP_LT) { 101f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK) { goto done; } 102f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 103f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = Y + T1 */ 104f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(t1, y, t1)) != CRYPT_OK) { goto done; } 105f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp(t1, modulus) != LTC_MP_LT) { 106f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK) { goto done; } 107f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 108f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* X = X - T2 */ 109f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(x, t2, x)) != CRYPT_OK) { goto done; } 110f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp_d(x, 0) == LTC_MP_LT) { 111f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(x, modulus, x)) != CRYPT_OK) { goto done; } 112f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 113f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T2 = 2T2 */ 114f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(t2, t2, t2)) != CRYPT_OK) { goto done; } 115f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp(t2, modulus) != LTC_MP_LT) { 116f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(t2, modulus, t2)) != CRYPT_OK) { goto done; } 117f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 118f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T2 = X + T2 */ 119f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(t2, x, t2)) != CRYPT_OK) { goto done; } 120f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp(t2, modulus) != LTC_MP_LT) { 121f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(t2, modulus, t2)) != CRYPT_OK) { goto done; } 122f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 123f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 124f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* if Z' != 1 */ 125f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (Q->z != NULL) { 126f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* Z = Z * Z' */ 127f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(z, Q->z, z)) != CRYPT_OK) { goto done; } 128f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(z, modulus, mp)) != CRYPT_OK) { goto done; } 129f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 130f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 131f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* Z = Z * X */ 132f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(z, x, z)) != CRYPT_OK) { goto done; } 133f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(z, modulus, mp)) != CRYPT_OK) { goto done; } 134f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 135f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = T1 * X */ 136f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(t1, x, t1)) != CRYPT_OK) { goto done; } 137f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } 138f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* X = X * X */ 139f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sqr(x, x)) != CRYPT_OK) { goto done; } 140f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK) { goto done; } 141f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T2 = T2 * x */ 142f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(t2, x, t2)) != CRYPT_OK) { goto done; } 143f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } 144f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T1 = T1 * X */ 145f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(t1, x, t1)) != CRYPT_OK) { goto done; } 146f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK) { goto done; } 147f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 148f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* X = Y*Y */ 149f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sqr(y, x)) != CRYPT_OK) { goto done; } 150f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK) { goto done; } 151f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* X = X - T2 */ 152f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(x, t2, x)) != CRYPT_OK) { goto done; } 153f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp_d(x, 0) == LTC_MP_LT) { 154f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(x, modulus, x)) != CRYPT_OK) { goto done; } 155f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 156f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 157f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T2 = T2 - X */ 158f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(t2, x, t2)) != CRYPT_OK) { goto done; } 159f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp_d(t2, 0) == LTC_MP_LT) { 160f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK) { goto done; } 161f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 162f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T2 = T2 - X */ 163f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(t2, x, t2)) != CRYPT_OK) { goto done; } 164f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp_d(t2, 0) == LTC_MP_LT) { 165f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK) { goto done; } 166f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 167f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* T2 = T2 * Y */ 168f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_mul(t2, y, t2)) != CRYPT_OK) { goto done; } 169f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK) { goto done; } 170f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* Y = T2 - T1 */ 171f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_sub(t2, t1, y)) != CRYPT_OK) { goto done; } 172f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp_d(y, 0) == LTC_MP_LT) { 173f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(y, modulus, y)) != CRYPT_OK) { goto done; } 174f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 175f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* Y = Y/2 */ 176f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_isodd(y)) { 177f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_add(y, modulus, y)) != CRYPT_OK) { goto done; } 178f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 179f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_div_2(y, y)) != CRYPT_OK) { goto done; } 180f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 181f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_copy(x, R->x)) != CRYPT_OK) { goto done; } 182f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_copy(y, R->y)) != CRYPT_OK) { goto done; } 183f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = mp_copy(z, R->z)) != CRYPT_OK) { goto done; } 184f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 185f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project err = CRYPT_OK; 186f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectdone: 187f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_clear_multi(t1, t2, x, y, z, NULL); 188f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 189f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 190f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 191f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 192f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 193f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_projective_add_point.c,v $ */ 194f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.13 $ */ 195f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/12/04 05:07:59 $ */ 196f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 197