2 * Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
12 * ECDSA low level APIs are deprecated for public use, but still ok for
15 #include "internal/deprecated.h"
17 #include <openssl/err.h>
18 #include <openssl/symhacks.h>
22 const EC_METHOD *EC_GFp_simple_method(void)
24 static const EC_METHOD ret = {
26 NID_X9_62_prime_field,
27 ec_GFp_simple_group_init,
28 ec_GFp_simple_group_finish,
29 ec_GFp_simple_group_clear_finish,
30 ec_GFp_simple_group_copy,
31 ec_GFp_simple_group_set_curve,
32 ec_GFp_simple_group_get_curve,
33 ec_GFp_simple_group_get_degree,
34 ec_group_simple_order_bits,
35 ec_GFp_simple_group_check_discriminant,
36 ec_GFp_simple_point_init,
37 ec_GFp_simple_point_finish,
38 ec_GFp_simple_point_clear_finish,
39 ec_GFp_simple_point_copy,
40 ec_GFp_simple_point_set_to_infinity,
41 ec_GFp_simple_point_set_affine_coordinates,
42 ec_GFp_simple_point_get_affine_coordinates,
47 ec_GFp_simple_is_at_infinity,
48 ec_GFp_simple_is_on_curve,
50 ec_GFp_simple_make_affine,
51 ec_GFp_simple_points_make_affine,
53 0 /* precompute_mult */ ,
54 0 /* have_precompute_mult */ ,
55 ec_GFp_simple_field_mul,
56 ec_GFp_simple_field_sqr,
58 ec_GFp_simple_field_inv,
59 0 /* field_encode */ ,
60 0 /* field_decode */ ,
61 0, /* field_set_to_one */
62 ec_key_simple_priv2oct,
63 ec_key_simple_oct2priv,
65 ec_key_simple_generate_key,
66 ec_key_simple_check_key,
67 ec_key_simple_generate_public_key,
70 ecdh_simple_compute_key,
71 ecdsa_simple_sign_setup,
72 ecdsa_simple_sign_sig,
73 ecdsa_simple_verify_sig,
74 0, /* field_inverse_mod_ord */
75 ec_GFp_simple_blind_coordinates,
76 ec_GFp_simple_ladder_pre,
77 ec_GFp_simple_ladder_step,
78 ec_GFp_simple_ladder_post
85 * Most method functions in this file are designed to work with
86 * non-trivial representations of field elements if necessary
87 * (see ecp_mont.c): while standard modular addition and subtraction
88 * are used, the field_mul and field_sqr methods will be used for
89 * multiplication, and field_encode and field_decode (if defined)
90 * will be used for converting between representations.
92 * Functions ec_GFp_simple_points_make_affine() and
93 * ec_GFp_simple_point_get_affine_coordinates() specifically assume
94 * that if a non-trivial representation is used, it is a Montgomery
95 * representation (i.e. 'encoding' means multiplying by some factor R).
98 int ec_GFp_simple_group_init(EC_GROUP *group)
100 group->field = BN_new();
103 if (group->field == NULL || group->a == NULL || group->b == NULL) {
104 BN_free(group->field);
109 group->a_is_minus3 = 0;
113 void ec_GFp_simple_group_finish(EC_GROUP *group)
115 BN_free(group->field);
120 void ec_GFp_simple_group_clear_finish(EC_GROUP *group)
122 BN_clear_free(group->field);
123 BN_clear_free(group->a);
124 BN_clear_free(group->b);
127 int ec_GFp_simple_group_copy(EC_GROUP *dest, const EC_GROUP *src)
129 if (!BN_copy(dest->field, src->field))
131 if (!BN_copy(dest->a, src->a))
133 if (!BN_copy(dest->b, src->b))
136 dest->a_is_minus3 = src->a_is_minus3;
141 int ec_GFp_simple_group_set_curve(EC_GROUP *group,
142 const BIGNUM *p, const BIGNUM *a,
143 const BIGNUM *b, BN_CTX *ctx)
146 BN_CTX *new_ctx = NULL;
149 /* p must be a prime > 3 */
150 if (BN_num_bits(p) <= 2 || !BN_is_odd(p)) {
151 ERR_raise(ERR_LIB_EC, EC_R_INVALID_FIELD);
156 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
162 tmp_a = BN_CTX_get(ctx);
167 if (!BN_copy(group->field, p))
169 BN_set_negative(group->field, 0);
172 if (!BN_nnmod(tmp_a, a, p, ctx))
174 if (group->meth->field_encode) {
175 if (!group->meth->field_encode(group, group->a, tmp_a, ctx))
177 } else if (!BN_copy(group->a, tmp_a))
181 if (!BN_nnmod(group->b, b, p, ctx))
183 if (group->meth->field_encode)
184 if (!group->meth->field_encode(group, group->b, group->b, ctx))
187 /* group->a_is_minus3 */
188 if (!BN_add_word(tmp_a, 3))
190 group->a_is_minus3 = (0 == BN_cmp(tmp_a, group->field));
196 BN_CTX_free(new_ctx);
200 int ec_GFp_simple_group_get_curve(const EC_GROUP *group, BIGNUM *p, BIGNUM *a,
201 BIGNUM *b, BN_CTX *ctx)
204 BN_CTX *new_ctx = NULL;
207 if (!BN_copy(p, group->field))
211 if (a != NULL || b != NULL) {
212 if (group->meth->field_decode) {
214 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
219 if (!group->meth->field_decode(group, a, group->a, ctx))
223 if (!group->meth->field_decode(group, b, group->b, ctx))
228 if (!BN_copy(a, group->a))
232 if (!BN_copy(b, group->b))
241 BN_CTX_free(new_ctx);
245 int ec_GFp_simple_group_get_degree(const EC_GROUP *group)
247 return BN_num_bits(group->field);
250 int ec_GFp_simple_group_check_discriminant(const EC_GROUP *group, BN_CTX *ctx)
253 BIGNUM *a, *b, *order, *tmp_1, *tmp_2;
254 const BIGNUM *p = group->field;
255 BN_CTX *new_ctx = NULL;
258 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
260 ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
267 tmp_1 = BN_CTX_get(ctx);
268 tmp_2 = BN_CTX_get(ctx);
269 order = BN_CTX_get(ctx);
273 if (group->meth->field_decode) {
274 if (!group->meth->field_decode(group, a, group->a, ctx))
276 if (!group->meth->field_decode(group, b, group->b, ctx))
279 if (!BN_copy(a, group->a))
281 if (!BN_copy(b, group->b))
286 * check the discriminant:
287 * y^2 = x^3 + a*x + b is an elliptic curve <=> 4*a^3 + 27*b^2 != 0 (mod p)
293 } else if (!BN_is_zero(b)) {
294 if (!BN_mod_sqr(tmp_1, a, p, ctx))
296 if (!BN_mod_mul(tmp_2, tmp_1, a, p, ctx))
298 if (!BN_lshift(tmp_1, tmp_2, 2))
302 if (!BN_mod_sqr(tmp_2, b, p, ctx))
304 if (!BN_mul_word(tmp_2, 27))
308 if (!BN_mod_add(a, tmp_1, tmp_2, p, ctx))
317 BN_CTX_free(new_ctx);
321 int ec_GFp_simple_point_init(EC_POINT *point)
328 if (point->X == NULL || point->Y == NULL || point->Z == NULL) {
337 void ec_GFp_simple_point_finish(EC_POINT *point)
344 void ec_GFp_simple_point_clear_finish(EC_POINT *point)
346 BN_clear_free(point->X);
347 BN_clear_free(point->Y);
348 BN_clear_free(point->Z);
352 int ec_GFp_simple_point_copy(EC_POINT *dest, const EC_POINT *src)
354 if (!BN_copy(dest->X, src->X))
356 if (!BN_copy(dest->Y, src->Y))
358 if (!BN_copy(dest->Z, src->Z))
360 dest->Z_is_one = src->Z_is_one;
361 dest->curve_name = src->curve_name;
366 int ec_GFp_simple_point_set_to_infinity(const EC_GROUP *group,
374 int ec_GFp_simple_set_Jprojective_coordinates_GFp(const EC_GROUP *group,
381 BN_CTX *new_ctx = NULL;
385 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
391 if (!BN_nnmod(point->X, x, group->field, ctx))
393 if (group->meth->field_encode) {
394 if (!group->meth->field_encode(group, point->X, point->X, ctx))
400 if (!BN_nnmod(point->Y, y, group->field, ctx))
402 if (group->meth->field_encode) {
403 if (!group->meth->field_encode(group, point->Y, point->Y, ctx))
411 if (!BN_nnmod(point->Z, z, group->field, ctx))
413 Z_is_one = BN_is_one(point->Z);
414 if (group->meth->field_encode) {
415 if (Z_is_one && (group->meth->field_set_to_one != 0)) {
416 if (!group->meth->field_set_to_one(group, point->Z, ctx))
420 meth->field_encode(group, point->Z, point->Z, ctx))
424 point->Z_is_one = Z_is_one;
430 BN_CTX_free(new_ctx);
434 int ec_GFp_simple_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
435 const EC_POINT *point,
436 BIGNUM *x, BIGNUM *y,
437 BIGNUM *z, BN_CTX *ctx)
439 BN_CTX *new_ctx = NULL;
442 if (group->meth->field_decode != 0) {
444 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
450 if (!group->meth->field_decode(group, x, point->X, ctx))
454 if (!group->meth->field_decode(group, y, point->Y, ctx))
458 if (!group->meth->field_decode(group, z, point->Z, ctx))
463 if (!BN_copy(x, point->X))
467 if (!BN_copy(y, point->Y))
471 if (!BN_copy(z, point->Z))
479 BN_CTX_free(new_ctx);
483 int ec_GFp_simple_point_set_affine_coordinates(const EC_GROUP *group,
486 const BIGNUM *y, BN_CTX *ctx)
488 if (x == NULL || y == NULL) {
490 * unlike for projective coordinates, we do not tolerate this
492 ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
496 return EC_POINT_set_Jprojective_coordinates_GFp(group, point, x, y,
497 BN_value_one(), ctx);
500 int ec_GFp_simple_point_get_affine_coordinates(const EC_GROUP *group,
501 const EC_POINT *point,
502 BIGNUM *x, BIGNUM *y,
505 BN_CTX *new_ctx = NULL;
506 BIGNUM *Z, *Z_1, *Z_2, *Z_3;
510 if (EC_POINT_is_at_infinity(group, point)) {
511 ERR_raise(ERR_LIB_EC, EC_R_POINT_AT_INFINITY);
516 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
523 Z_1 = BN_CTX_get(ctx);
524 Z_2 = BN_CTX_get(ctx);
525 Z_3 = BN_CTX_get(ctx);
529 /* transform (X, Y, Z) into (x, y) := (X/Z^2, Y/Z^3) */
531 if (group->meth->field_decode) {
532 if (!group->meth->field_decode(group, Z, point->Z, ctx))
540 if (group->meth->field_decode) {
542 if (!group->meth->field_decode(group, x, point->X, ctx))
546 if (!group->meth->field_decode(group, y, point->Y, ctx))
551 if (!BN_copy(x, point->X))
555 if (!BN_copy(y, point->Y))
560 if (!group->meth->field_inv(group, Z_1, Z_, ctx)) {
561 ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
565 if (group->meth->field_encode == 0) {
566 /* field_sqr works on standard representation */
567 if (!group->meth->field_sqr(group, Z_2, Z_1, ctx))
570 if (!BN_mod_sqr(Z_2, Z_1, group->field, ctx))
576 * in the Montgomery case, field_mul will cancel out Montgomery
579 if (!group->meth->field_mul(group, x, point->X, Z_2, ctx))
584 if (group->meth->field_encode == 0) {
586 * field_mul works on standard representation
588 if (!group->meth->field_mul(group, Z_3, Z_2, Z_1, ctx))
591 if (!BN_mod_mul(Z_3, Z_2, Z_1, group->field, ctx))
596 * in the Montgomery case, field_mul will cancel out Montgomery
599 if (!group->meth->field_mul(group, y, point->Y, Z_3, ctx))
608 BN_CTX_free(new_ctx);
612 int ec_GFp_simple_add(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a,
613 const EC_POINT *b, BN_CTX *ctx)
615 int (*field_mul) (const EC_GROUP *, BIGNUM *, const BIGNUM *,
616 const BIGNUM *, BN_CTX *);
617 int (*field_sqr) (const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
619 BN_CTX *new_ctx = NULL;
620 BIGNUM *n0, *n1, *n2, *n3, *n4, *n5, *n6;
624 return EC_POINT_dbl(group, r, a, ctx);
625 if (EC_POINT_is_at_infinity(group, a))
626 return EC_POINT_copy(r, b);
627 if (EC_POINT_is_at_infinity(group, b))
628 return EC_POINT_copy(r, a);
630 field_mul = group->meth->field_mul;
631 field_sqr = group->meth->field_sqr;
635 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
641 n0 = BN_CTX_get(ctx);
642 n1 = BN_CTX_get(ctx);
643 n2 = BN_CTX_get(ctx);
644 n3 = BN_CTX_get(ctx);
645 n4 = BN_CTX_get(ctx);
646 n5 = BN_CTX_get(ctx);
647 n6 = BN_CTX_get(ctx);
652 * Note that in this function we must not read components of 'a' or 'b'
653 * once we have written the corresponding components of 'r'. ('r' might
654 * be one of 'a' or 'b'.)
659 if (!BN_copy(n1, a->X))
661 if (!BN_copy(n2, a->Y))
666 if (!field_sqr(group, n0, b->Z, ctx))
668 if (!field_mul(group, n1, a->X, n0, ctx))
670 /* n1 = X_a * Z_b^2 */
672 if (!field_mul(group, n0, n0, b->Z, ctx))
674 if (!field_mul(group, n2, a->Y, n0, ctx))
676 /* n2 = Y_a * Z_b^3 */
681 if (!BN_copy(n3, b->X))
683 if (!BN_copy(n4, b->Y))
688 if (!field_sqr(group, n0, a->Z, ctx))
690 if (!field_mul(group, n3, b->X, n0, ctx))
692 /* n3 = X_b * Z_a^2 */
694 if (!field_mul(group, n0, n0, a->Z, ctx))
696 if (!field_mul(group, n4, b->Y, n0, ctx))
698 /* n4 = Y_b * Z_a^3 */
702 if (!BN_mod_sub_quick(n5, n1, n3, p))
704 if (!BN_mod_sub_quick(n6, n2, n4, p))
709 if (BN_is_zero(n5)) {
710 if (BN_is_zero(n6)) {
711 /* a is the same point as b */
713 ret = EC_POINT_dbl(group, r, a, ctx);
717 /* a is the inverse of b */
726 if (!BN_mod_add_quick(n1, n1, n3, p))
728 if (!BN_mod_add_quick(n2, n2, n4, p))
734 if (a->Z_is_one && b->Z_is_one) {
735 if (!BN_copy(r->Z, n5))
739 if (!BN_copy(n0, b->Z))
741 } else if (b->Z_is_one) {
742 if (!BN_copy(n0, a->Z))
745 if (!field_mul(group, n0, a->Z, b->Z, ctx))
748 if (!field_mul(group, r->Z, n0, n5, ctx))
752 /* Z_r = Z_a * Z_b * n5 */
755 if (!field_sqr(group, n0, n6, ctx))
757 if (!field_sqr(group, n4, n5, ctx))
759 if (!field_mul(group, n3, n1, n4, ctx))
761 if (!BN_mod_sub_quick(r->X, n0, n3, p))
763 /* X_r = n6^2 - n5^2 * 'n7' */
766 if (!BN_mod_lshift1_quick(n0, r->X, p))
768 if (!BN_mod_sub_quick(n0, n3, n0, p))
770 /* n9 = n5^2 * 'n7' - 2 * X_r */
773 if (!field_mul(group, n0, n0, n6, ctx))
775 if (!field_mul(group, n5, n4, n5, ctx))
776 goto end; /* now n5 is n5^3 */
777 if (!field_mul(group, n1, n2, n5, ctx))
779 if (!BN_mod_sub_quick(n0, n0, n1, p))
782 if (!BN_add(n0, n0, p))
784 /* now 0 <= n0 < 2*p, and n0 is even */
785 if (!BN_rshift1(r->Y, n0))
787 /* Y_r = (n6 * 'n9' - 'n8' * 'n5^3') / 2 */
793 BN_CTX_free(new_ctx);
797 int ec_GFp_simple_dbl(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a,
800 int (*field_mul) (const EC_GROUP *, BIGNUM *, const BIGNUM *,
801 const BIGNUM *, BN_CTX *);
802 int (*field_sqr) (const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
804 BN_CTX *new_ctx = NULL;
805 BIGNUM *n0, *n1, *n2, *n3;
808 if (EC_POINT_is_at_infinity(group, a)) {
814 field_mul = group->meth->field_mul;
815 field_sqr = group->meth->field_sqr;
819 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
825 n0 = BN_CTX_get(ctx);
826 n1 = BN_CTX_get(ctx);
827 n2 = BN_CTX_get(ctx);
828 n3 = BN_CTX_get(ctx);
833 * Note that in this function we must not read components of 'a' once we
834 * have written the corresponding components of 'r'. ('r' might the same
840 if (!field_sqr(group, n0, a->X, ctx))
842 if (!BN_mod_lshift1_quick(n1, n0, p))
844 if (!BN_mod_add_quick(n0, n0, n1, p))
846 if (!BN_mod_add_quick(n1, n0, group->a, p))
848 /* n1 = 3 * X_a^2 + a_curve */
849 } else if (group->a_is_minus3) {
850 if (!field_sqr(group, n1, a->Z, ctx))
852 if (!BN_mod_add_quick(n0, a->X, n1, p))
854 if (!BN_mod_sub_quick(n2, a->X, n1, p))
856 if (!field_mul(group, n1, n0, n2, ctx))
858 if (!BN_mod_lshift1_quick(n0, n1, p))
860 if (!BN_mod_add_quick(n1, n0, n1, p))
863 * n1 = 3 * (X_a + Z_a^2) * (X_a - Z_a^2)
864 * = 3 * X_a^2 - 3 * Z_a^4
867 if (!field_sqr(group, n0, a->X, ctx))
869 if (!BN_mod_lshift1_quick(n1, n0, p))
871 if (!BN_mod_add_quick(n0, n0, n1, p))
873 if (!field_sqr(group, n1, a->Z, ctx))
875 if (!field_sqr(group, n1, n1, ctx))
877 if (!field_mul(group, n1, n1, group->a, ctx))
879 if (!BN_mod_add_quick(n1, n1, n0, p))
881 /* n1 = 3 * X_a^2 + a_curve * Z_a^4 */
886 if (!BN_copy(n0, a->Y))
889 if (!field_mul(group, n0, a->Y, a->Z, ctx))
892 if (!BN_mod_lshift1_quick(r->Z, n0, p))
895 /* Z_r = 2 * Y_a * Z_a */
898 if (!field_sqr(group, n3, a->Y, ctx))
900 if (!field_mul(group, n2, a->X, n3, ctx))
902 if (!BN_mod_lshift_quick(n2, n2, 2, p))
904 /* n2 = 4 * X_a * Y_a^2 */
907 if (!BN_mod_lshift1_quick(n0, n2, p))
909 if (!field_sqr(group, r->X, n1, ctx))
911 if (!BN_mod_sub_quick(r->X, r->X, n0, p))
913 /* X_r = n1^2 - 2 * n2 */
916 if (!field_sqr(group, n0, n3, ctx))
918 if (!BN_mod_lshift_quick(n3, n0, 3, p))
923 if (!BN_mod_sub_quick(n0, n2, r->X, p))
925 if (!field_mul(group, n0, n1, n0, ctx))
927 if (!BN_mod_sub_quick(r->Y, n0, n3, p))
929 /* Y_r = n1 * (n2 - X_r) - n3 */
935 BN_CTX_free(new_ctx);
939 int ec_GFp_simple_invert(const EC_GROUP *group, EC_POINT *point, BN_CTX *ctx)
941 if (EC_POINT_is_at_infinity(group, point) || BN_is_zero(point->Y))
942 /* point is its own inverse */
945 return BN_usub(point->Y, group->field, point->Y);
948 int ec_GFp_simple_is_at_infinity(const EC_GROUP *group, const EC_POINT *point)
950 return BN_is_zero(point->Z);
953 int ec_GFp_simple_is_on_curve(const EC_GROUP *group, const EC_POINT *point,
956 int (*field_mul) (const EC_GROUP *, BIGNUM *, const BIGNUM *,
957 const BIGNUM *, BN_CTX *);
958 int (*field_sqr) (const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
960 BN_CTX *new_ctx = NULL;
961 BIGNUM *rh, *tmp, *Z4, *Z6;
964 if (EC_POINT_is_at_infinity(group, point))
967 field_mul = group->meth->field_mul;
968 field_sqr = group->meth->field_sqr;
972 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
978 rh = BN_CTX_get(ctx);
979 tmp = BN_CTX_get(ctx);
980 Z4 = BN_CTX_get(ctx);
981 Z6 = BN_CTX_get(ctx);
986 * We have a curve defined by a Weierstrass equation
987 * y^2 = x^3 + a*x + b.
988 * The point to consider is given in Jacobian projective coordinates
989 * where (X, Y, Z) represents (x, y) = (X/Z^2, Y/Z^3).
990 * Substituting this and multiplying by Z^6 transforms the above equation into
991 * Y^2 = X^3 + a*X*Z^4 + b*Z^6.
992 * To test this, we add up the right-hand side in 'rh'.
996 if (!field_sqr(group, rh, point->X, ctx))
999 if (!point->Z_is_one) {
1000 if (!field_sqr(group, tmp, point->Z, ctx))
1002 if (!field_sqr(group, Z4, tmp, ctx))
1004 if (!field_mul(group, Z6, Z4, tmp, ctx))
1007 /* rh := (rh + a*Z^4)*X */
1008 if (group->a_is_minus3) {
1009 if (!BN_mod_lshift1_quick(tmp, Z4, p))
1011 if (!BN_mod_add_quick(tmp, tmp, Z4, p))
1013 if (!BN_mod_sub_quick(rh, rh, tmp, p))
1015 if (!field_mul(group, rh, rh, point->X, ctx))
1018 if (!field_mul(group, tmp, Z4, group->a, ctx))
1020 if (!BN_mod_add_quick(rh, rh, tmp, p))
1022 if (!field_mul(group, rh, rh, point->X, ctx))
1026 /* rh := rh + b*Z^6 */
1027 if (!field_mul(group, tmp, group->b, Z6, ctx))
1029 if (!BN_mod_add_quick(rh, rh, tmp, p))
1032 /* point->Z_is_one */
1034 /* rh := (rh + a)*X */
1035 if (!BN_mod_add_quick(rh, rh, group->a, p))
1037 if (!field_mul(group, rh, rh, point->X, ctx))
1040 if (!BN_mod_add_quick(rh, rh, group->b, p))
1045 if (!field_sqr(group, tmp, point->Y, ctx))
1048 ret = (0 == BN_ucmp(tmp, rh));
1052 BN_CTX_free(new_ctx);
1056 int ec_GFp_simple_cmp(const EC_GROUP *group, const EC_POINT *a,
1057 const EC_POINT *b, BN_CTX *ctx)
1062 * 0 equal (in affine coordinates)
1066 int (*field_mul) (const EC_GROUP *, BIGNUM *, const BIGNUM *,
1067 const BIGNUM *, BN_CTX *);
1068 int (*field_sqr) (const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
1069 BN_CTX *new_ctx = NULL;
1070 BIGNUM *tmp1, *tmp2, *Za23, *Zb23;
1071 const BIGNUM *tmp1_, *tmp2_;
1074 if (EC_POINT_is_at_infinity(group, a)) {
1075 return EC_POINT_is_at_infinity(group, b) ? 0 : 1;
1078 if (EC_POINT_is_at_infinity(group, b))
1081 if (a->Z_is_one && b->Z_is_one) {
1082 return ((BN_cmp(a->X, b->X) == 0) && BN_cmp(a->Y, b->Y) == 0) ? 0 : 1;
1085 field_mul = group->meth->field_mul;
1086 field_sqr = group->meth->field_sqr;
1089 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
1095 tmp1 = BN_CTX_get(ctx);
1096 tmp2 = BN_CTX_get(ctx);
1097 Za23 = BN_CTX_get(ctx);
1098 Zb23 = BN_CTX_get(ctx);
1103 * We have to decide whether
1104 * (X_a/Z_a^2, Y_a/Z_a^3) = (X_b/Z_b^2, Y_b/Z_b^3),
1105 * or equivalently, whether
1106 * (X_a*Z_b^2, Y_a*Z_b^3) = (X_b*Z_a^2, Y_b*Z_a^3).
1110 if (!field_sqr(group, Zb23, b->Z, ctx))
1112 if (!field_mul(group, tmp1, a->X, Zb23, ctx))
1118 if (!field_sqr(group, Za23, a->Z, ctx))
1120 if (!field_mul(group, tmp2, b->X, Za23, ctx))
1126 /* compare X_a*Z_b^2 with X_b*Z_a^2 */
1127 if (BN_cmp(tmp1_, tmp2_) != 0) {
1128 ret = 1; /* points differ */
1133 if (!field_mul(group, Zb23, Zb23, b->Z, ctx))
1135 if (!field_mul(group, tmp1, a->Y, Zb23, ctx))
1141 if (!field_mul(group, Za23, Za23, a->Z, ctx))
1143 if (!field_mul(group, tmp2, b->Y, Za23, ctx))
1149 /* compare Y_a*Z_b^3 with Y_b*Z_a^3 */
1150 if (BN_cmp(tmp1_, tmp2_) != 0) {
1151 ret = 1; /* points differ */
1155 /* points are equal */
1160 BN_CTX_free(new_ctx);
1164 int ec_GFp_simple_make_affine(const EC_GROUP *group, EC_POINT *point,
1167 BN_CTX *new_ctx = NULL;
1171 if (point->Z_is_one || EC_POINT_is_at_infinity(group, point))
1175 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
1181 x = BN_CTX_get(ctx);
1182 y = BN_CTX_get(ctx);
1186 if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx))
1188 if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
1190 if (!point->Z_is_one) {
1191 ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
1199 BN_CTX_free(new_ctx);
1203 int ec_GFp_simple_points_make_affine(const EC_GROUP *group, size_t num,
1204 EC_POINT *points[], BN_CTX *ctx)
1206 BN_CTX *new_ctx = NULL;
1207 BIGNUM *tmp, *tmp_Z;
1208 BIGNUM **prod_Z = NULL;
1216 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
1222 tmp = BN_CTX_get(ctx);
1223 tmp_Z = BN_CTX_get(ctx);
1227 prod_Z = OPENSSL_malloc(num * sizeof(prod_Z[0]));
1230 for (i = 0; i < num; i++) {
1231 prod_Z[i] = BN_new();
1232 if (prod_Z[i] == NULL)
1237 * Set each prod_Z[i] to the product of points[0]->Z .. points[i]->Z,
1238 * skipping any zero-valued inputs (pretend that they're 1).
1241 if (!BN_is_zero(points[0]->Z)) {
1242 if (!BN_copy(prod_Z[0], points[0]->Z))
1245 if (group->meth->field_set_to_one != 0) {
1246 if (!group->meth->field_set_to_one(group, prod_Z[0], ctx))
1249 if (!BN_one(prod_Z[0]))
1254 for (i = 1; i < num; i++) {
1255 if (!BN_is_zero(points[i]->Z)) {
1257 meth->field_mul(group, prod_Z[i], prod_Z[i - 1], points[i]->Z,
1261 if (!BN_copy(prod_Z[i], prod_Z[i - 1]))
1267 * Now use a single explicit inversion to replace every non-zero
1268 * points[i]->Z by its inverse.
1271 if (!group->meth->field_inv(group, tmp, prod_Z[num - 1], ctx)) {
1272 ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
1275 if (group->meth->field_encode != 0) {
1277 * In the Montgomery case, we just turned R*H (representing H) into
1278 * 1/(R*H), but we need R*(1/H) (representing 1/H); i.e. we need to
1279 * multiply by the Montgomery factor twice.
1281 if (!group->meth->field_encode(group, tmp, tmp, ctx))
1283 if (!group->meth->field_encode(group, tmp, tmp, ctx))
1287 for (i = num - 1; i > 0; --i) {
1289 * Loop invariant: tmp is the product of the inverses of points[0]->Z
1290 * .. points[i]->Z (zero-valued inputs skipped).
1292 if (!BN_is_zero(points[i]->Z)) {
1294 * Set tmp_Z to the inverse of points[i]->Z (as product of Z
1295 * inverses 0 .. i, Z values 0 .. i - 1).
1298 meth->field_mul(group, tmp_Z, prod_Z[i - 1], tmp, ctx))
1301 * Update tmp to satisfy the loop invariant for i - 1.
1303 if (!group->meth->field_mul(group, tmp, tmp, points[i]->Z, ctx))
1305 /* Replace points[i]->Z by its inverse. */
1306 if (!BN_copy(points[i]->Z, tmp_Z))
1311 if (!BN_is_zero(points[0]->Z)) {
1312 /* Replace points[0]->Z by its inverse. */
1313 if (!BN_copy(points[0]->Z, tmp))
1317 /* Finally, fix up the X and Y coordinates for all points. */
1319 for (i = 0; i < num; i++) {
1320 EC_POINT *p = points[i];
1322 if (!BN_is_zero(p->Z)) {
1323 /* turn (X, Y, 1/Z) into (X/Z^2, Y/Z^3, 1) */
1325 if (!group->meth->field_sqr(group, tmp, p->Z, ctx))
1327 if (!group->meth->field_mul(group, p->X, p->X, tmp, ctx))
1330 if (!group->meth->field_mul(group, tmp, tmp, p->Z, ctx))
1332 if (!group->meth->field_mul(group, p->Y, p->Y, tmp, ctx))
1335 if (group->meth->field_set_to_one != 0) {
1336 if (!group->meth->field_set_to_one(group, p->Z, ctx))
1350 BN_CTX_free(new_ctx);
1351 if (prod_Z != NULL) {
1352 for (i = 0; i < num; i++) {
1353 if (prod_Z[i] == NULL)
1355 BN_clear_free(prod_Z[i]);
1357 OPENSSL_free(prod_Z);
1362 int ec_GFp_simple_field_mul(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
1363 const BIGNUM *b, BN_CTX *ctx)
1365 return BN_mod_mul(r, a, b, group->field, ctx);
1368 int ec_GFp_simple_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
1371 return BN_mod_sqr(r, a, group->field, ctx);
1375 * Computes the multiplicative inverse of a in GF(p), storing the result in r.
1376 * If a is zero (or equivalent), you'll get a EC_R_CANNOT_INVERT error.
1377 * Since we don't have a Mont structure here, SCA hardening is with blinding.
1378 * NB: "a" must be in _decoded_ form. (i.e. field_decode must precede.)
1380 int ec_GFp_simple_field_inv(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
1384 BN_CTX *new_ctx = NULL;
1388 && (ctx = new_ctx = BN_CTX_secure_new_ex(group->libctx)) == NULL)
1392 if ((e = BN_CTX_get(ctx)) == NULL)
1396 if (!BN_priv_rand_range_ex(e, group->field, ctx))
1398 } while (BN_is_zero(e));
1401 if (!group->meth->field_mul(group, r, a, e, ctx))
1403 /* r := 1/(a * e) */
1404 if (!BN_mod_inverse(r, r, group->field, ctx)) {
1405 ERR_raise(ERR_LIB_EC, EC_R_CANNOT_INVERT);
1408 /* r := e/(a * e) = 1/a */
1409 if (!group->meth->field_mul(group, r, r, e, ctx))
1416 BN_CTX_free(new_ctx);
1421 * Apply randomization of EC point projective coordinates:
1423 * (X, Y ,Z ) = (lambda^2*X, lambda^3*Y, lambda*Z)
1424 * lambda = [1,group->field)
1427 int ec_GFp_simple_blind_coordinates(const EC_GROUP *group, EC_POINT *p,
1431 BIGNUM *lambda = NULL;
1432 BIGNUM *temp = NULL;
1435 lambda = BN_CTX_get(ctx);
1436 temp = BN_CTX_get(ctx);
1438 ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
1443 * Make sure lambda is not zero.
1444 * If the RNG fails, we cannot blind but nevertheless want
1445 * code to continue smoothly and not clobber the error stack.
1449 ret = BN_priv_rand_range_ex(lambda, group->field, ctx);
1455 } while (BN_is_zero(lambda));
1457 /* if field_encode defined convert between representations */
1458 if ((group->meth->field_encode != NULL
1459 && !group->meth->field_encode(group, lambda, lambda, ctx))
1460 || !group->meth->field_mul(group, p->Z, p->Z, lambda, ctx)
1461 || !group->meth->field_sqr(group, temp, lambda, ctx)
1462 || !group->meth->field_mul(group, p->X, p->X, temp, ctx)
1463 || !group->meth->field_mul(group, temp, temp, lambda, ctx)
1464 || !group->meth->field_mul(group, p->Y, p->Y, temp, ctx))
1477 * - p: affine coordinates
1480 * - s := p, r := 2p: blinded projective (homogeneous) coordinates
1482 * For doubling we use Formula 3 from Izu-Takagi "A fast parallel elliptic curve
1483 * multiplication resistant against side channel attacks" appendix, described at
1484 * https://hyperelliptic.org/EFD/g1p/auto-shortw-xz.html#doubling-dbl-2002-it-2
1485 * simplified for Z1=1.
1487 * Blinding uses the equivalence relation (\lambda X, \lambda Y, \lambda Z)
1488 * for any non-zero \lambda that holds for projective (homogeneous) coords.
1490 int ec_GFp_simple_ladder_pre(const EC_GROUP *group,
1491 EC_POINT *r, EC_POINT *s,
1492 EC_POINT *p, BN_CTX *ctx)
1494 BIGNUM *t1, *t2, *t3, *t4, *t5 = NULL;
1502 if (!p->Z_is_one /* r := 2p */
1503 || !group->meth->field_sqr(group, t3, p->X, ctx)
1504 || !BN_mod_sub_quick(t4, t3, group->a, group->field)
1505 || !group->meth->field_sqr(group, t4, t4, ctx)
1506 || !group->meth->field_mul(group, t5, p->X, group->b, ctx)
1507 || !BN_mod_lshift_quick(t5, t5, 3, group->field)
1508 /* r->X coord output */
1509 || !BN_mod_sub_quick(r->X, t4, t5, group->field)
1510 || !BN_mod_add_quick(t1, t3, group->a, group->field)
1511 || !group->meth->field_mul(group, t2, p->X, t1, ctx)
1512 || !BN_mod_add_quick(t2, group->b, t2, group->field)
1513 /* r->Z coord output */
1514 || !BN_mod_lshift_quick(r->Z, t2, 2, group->field))
1517 /* make sure lambda (r->Y here for storage) is not zero */
1519 if (!BN_priv_rand_range_ex(r->Y, group->field, ctx))
1521 } while (BN_is_zero(r->Y));
1523 /* make sure lambda (s->Z here for storage) is not zero */
1525 if (!BN_priv_rand_range_ex(s->Z, group->field, ctx))
1527 } while (BN_is_zero(s->Z));
1529 /* if field_encode defined convert between representations */
1530 if (group->meth->field_encode != NULL
1531 && (!group->meth->field_encode(group, r->Y, r->Y, ctx)
1532 || !group->meth->field_encode(group, s->Z, s->Z, ctx)))
1535 /* blind r and s independently */
1536 if (!group->meth->field_mul(group, r->Z, r->Z, r->Y, ctx)
1537 || !group->meth->field_mul(group, r->X, r->X, r->Y, ctx)
1538 || !group->meth->field_mul(group, s->X, p->X, s->Z, ctx)) /* s := p */
1549 * - s, r: projective (homogeneous) coordinates
1550 * - p: affine coordinates
1553 * - s := r + s, r := 2r: projective (homogeneous) coordinates
1555 * Differential addition-and-doubling using Eq. (9) and (10) from Izu-Takagi
1556 * "A fast parallel elliptic curve multiplication resistant against side channel
1557 * attacks", as described at
1558 * https://hyperelliptic.org/EFD/g1p/auto-shortw-xz.html#ladder-mladd-2002-it-4
1560 int ec_GFp_simple_ladder_step(const EC_GROUP *group,
1561 EC_POINT *r, EC_POINT *s,
1562 EC_POINT *p, BN_CTX *ctx)
1565 BIGNUM *t0, *t1, *t2, *t3, *t4, *t5, *t6 = NULL;
1568 t0 = BN_CTX_get(ctx);
1569 t1 = BN_CTX_get(ctx);
1570 t2 = BN_CTX_get(ctx);
1571 t3 = BN_CTX_get(ctx);
1572 t4 = BN_CTX_get(ctx);
1573 t5 = BN_CTX_get(ctx);
1574 t6 = BN_CTX_get(ctx);
1577 || !group->meth->field_mul(group, t6, r->X, s->X, ctx)
1578 || !group->meth->field_mul(group, t0, r->Z, s->Z, ctx)
1579 || !group->meth->field_mul(group, t4, r->X, s->Z, ctx)
1580 || !group->meth->field_mul(group, t3, r->Z, s->X, ctx)
1581 || !group->meth->field_mul(group, t5, group->a, t0, ctx)
1582 || !BN_mod_add_quick(t5, t6, t5, group->field)
1583 || !BN_mod_add_quick(t6, t3, t4, group->field)
1584 || !group->meth->field_mul(group, t5, t6, t5, ctx)
1585 || !group->meth->field_sqr(group, t0, t0, ctx)
1586 || !BN_mod_lshift_quick(t2, group->b, 2, group->field)
1587 || !group->meth->field_mul(group, t0, t2, t0, ctx)
1588 || !BN_mod_lshift1_quick(t5, t5, group->field)
1589 || !BN_mod_sub_quick(t3, t4, t3, group->field)
1590 /* s->Z coord output */
1591 || !group->meth->field_sqr(group, s->Z, t3, ctx)
1592 || !group->meth->field_mul(group, t4, s->Z, p->X, ctx)
1593 || !BN_mod_add_quick(t0, t0, t5, group->field)
1594 /* s->X coord output */
1595 || !BN_mod_sub_quick(s->X, t0, t4, group->field)
1596 || !group->meth->field_sqr(group, t4, r->X, ctx)
1597 || !group->meth->field_sqr(group, t5, r->Z, ctx)
1598 || !group->meth->field_mul(group, t6, t5, group->a, ctx)
1599 || !BN_mod_add_quick(t1, r->X, r->Z, group->field)
1600 || !group->meth->field_sqr(group, t1, t1, ctx)
1601 || !BN_mod_sub_quick(t1, t1, t4, group->field)
1602 || !BN_mod_sub_quick(t1, t1, t5, group->field)
1603 || !BN_mod_sub_quick(t3, t4, t6, group->field)
1604 || !group->meth->field_sqr(group, t3, t3, ctx)
1605 || !group->meth->field_mul(group, t0, t5, t1, ctx)
1606 || !group->meth->field_mul(group, t0, t2, t0, ctx)
1607 /* r->X coord output */
1608 || !BN_mod_sub_quick(r->X, t3, t0, group->field)
1609 || !BN_mod_add_quick(t3, t4, t6, group->field)
1610 || !group->meth->field_sqr(group, t4, t5, ctx)
1611 || !group->meth->field_mul(group, t4, t4, t2, ctx)
1612 || !group->meth->field_mul(group, t1, t1, t3, ctx)
1613 || !BN_mod_lshift1_quick(t1, t1, group->field)
1614 /* r->Z coord output */
1615 || !BN_mod_add_quick(r->Z, t4, t1, group->field))
1627 * - s, r: projective (homogeneous) coordinates
1628 * - p: affine coordinates
1631 * - r := (x,y): affine coordinates
1633 * Recovers the y-coordinate of r using Eq. (8) from Brier-Joye, "Weierstrass
1634 * Elliptic Curves and Side-Channel Attacks", modified to work in mixed
1635 * projective coords, i.e. p is affine and (r,s) in projective (homogeneous)
1636 * coords, and return r in affine coordinates.
1638 * X4 = two*Y1*X2*Z3*Z2;
1639 * Y4 = two*b*Z3*SQR(Z2) + Z3*(a*Z2+X1*X2)*(X1*Z2+X2) - X3*SQR(X1*Z2-X2);
1640 * Z4 = two*Y1*Z3*SQR(Z2);
1643 * - Z2==0 implies r is at infinity (handled by the BN_is_zero(r->Z) branch);
1644 * - Z3==0 implies s is at infinity (handled by the BN_is_zero(s->Z) branch);
1645 * - Y1==0 implies p has order 2, so either r or s are infinity and handled by
1646 * one of the BN_is_zero(...) branches.
1648 int ec_GFp_simple_ladder_post(const EC_GROUP *group,
1649 EC_POINT *r, EC_POINT *s,
1650 EC_POINT *p, BN_CTX *ctx)
1653 BIGNUM *t0, *t1, *t2, *t3, *t4, *t5, *t6 = NULL;
1655 if (BN_is_zero(r->Z))
1656 return EC_POINT_set_to_infinity(group, r);
1658 if (BN_is_zero(s->Z)) {
1659 if (!EC_POINT_copy(r, p)
1660 || !EC_POINT_invert(group, r, ctx))
1666 t0 = BN_CTX_get(ctx);
1667 t1 = BN_CTX_get(ctx);
1668 t2 = BN_CTX_get(ctx);
1669 t3 = BN_CTX_get(ctx);
1670 t4 = BN_CTX_get(ctx);
1671 t5 = BN_CTX_get(ctx);
1672 t6 = BN_CTX_get(ctx);
1675 || !BN_mod_lshift1_quick(t4, p->Y, group->field)
1676 || !group->meth->field_mul(group, t6, r->X, t4, ctx)
1677 || !group->meth->field_mul(group, t6, s->Z, t6, ctx)
1678 || !group->meth->field_mul(group, t5, r->Z, t6, ctx)
1679 || !BN_mod_lshift1_quick(t1, group->b, group->field)
1680 || !group->meth->field_mul(group, t1, s->Z, t1, ctx)
1681 || !group->meth->field_sqr(group, t3, r->Z, ctx)
1682 || !group->meth->field_mul(group, t2, t3, t1, ctx)
1683 || !group->meth->field_mul(group, t6, r->Z, group->a, ctx)
1684 || !group->meth->field_mul(group, t1, p->X, r->X, ctx)
1685 || !BN_mod_add_quick(t1, t1, t6, group->field)
1686 || !group->meth->field_mul(group, t1, s->Z, t1, ctx)
1687 || !group->meth->field_mul(group, t0, p->X, r->Z, ctx)
1688 || !BN_mod_add_quick(t6, r->X, t0, group->field)
1689 || !group->meth->field_mul(group, t6, t6, t1, ctx)
1690 || !BN_mod_add_quick(t6, t6, t2, group->field)
1691 || !BN_mod_sub_quick(t0, t0, r->X, group->field)
1692 || !group->meth->field_sqr(group, t0, t0, ctx)
1693 || !group->meth->field_mul(group, t0, t0, s->X, ctx)
1694 || !BN_mod_sub_quick(t0, t6, t0, group->field)
1695 || !group->meth->field_mul(group, t1, s->Z, t4, ctx)
1696 || !group->meth->field_mul(group, t1, t3, t1, ctx)
1697 || (group->meth->field_decode != NULL
1698 && !group->meth->field_decode(group, t1, t1, ctx))
1699 || !group->meth->field_inv(group, t1, t1, ctx)
1700 || (group->meth->field_encode != NULL
1701 && !group->meth->field_encode(group, t1, t1, ctx))
1702 || !group->meth->field_mul(group, r->X, t5, t1, ctx)
1703 || !group->meth->field_mul(group, r->Y, t0, t1, ctx))
1706 if (group->meth->field_set_to_one != NULL) {
1707 if (!group->meth->field_set_to_one(group, r->Z, ctx))