1 /* crypto/ec/ec2_smpl.c */
2 /* ====================================================================
3 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
5 * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
6 * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
7 * to the OpenSSL project.
9 * The ECC Code is licensed pursuant to the OpenSSL open source
10 * license provided below.
12 * The software is originally written by Sheueling Chang Shantz and
13 * Douglas Stebila of Sun Microsystems Laboratories.
16 /* ====================================================================
17 * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
23 * 1. Redistributions of source code must retain the above copyright
24 * notice, this list of conditions and the following disclaimer.
26 * 2. Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in
28 * the documentation and/or other materials provided with the
31 * 3. All advertising materials mentioning features or use of this
32 * software must display the following acknowledgment:
33 * "This product includes software developed by the OpenSSL Project
34 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
36 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
37 * endorse or promote products derived from this software without
38 * prior written permission. For written permission, please contact
39 * openssl-core@openssl.org.
41 * 5. Products derived from this software may not be called "OpenSSL"
42 * nor may "OpenSSL" appear in their names without prior written
43 * permission of the OpenSSL Project.
45 * 6. Redistributions of any form whatsoever must retain the following
47 * "This product includes software developed by the OpenSSL Project
48 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
50 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
51 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
53 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
54 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
55 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
56 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
57 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
58 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
59 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
60 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
61 * OF THE POSSIBILITY OF SUCH DAMAGE.
62 * ====================================================================
64 * This product includes cryptographic software written by Eric Young
65 * (eay@cryptsoft.com). This product includes software written by Tim
66 * Hudson (tjh@cryptsoft.com).
70 #include <openssl/err.h>
74 #ifndef OPENSSL_NO_EC2M
77 const EC_METHOD *EC_GF2m_simple_method(void)
79 static const EC_METHOD ret = {
81 NID_X9_62_characteristic_two_field,
82 ec_GF2m_simple_group_init,
83 ec_GF2m_simple_group_finish,
84 ec_GF2m_simple_group_clear_finish,
85 ec_GF2m_simple_group_copy,
86 ec_GF2m_simple_group_set_curve,
87 ec_GF2m_simple_group_get_curve,
88 ec_GF2m_simple_group_get_degree,
89 ec_GF2m_simple_group_check_discriminant,
90 ec_GF2m_simple_point_init,
91 ec_GF2m_simple_point_finish,
92 ec_GF2m_simple_point_clear_finish,
93 ec_GF2m_simple_point_copy,
94 ec_GF2m_simple_point_set_to_infinity,
95 0 /* set_Jprojective_coordinates_GFp */,
96 0 /* get_Jprojective_coordinates_GFp */,
97 ec_GF2m_simple_point_set_affine_coordinates,
98 ec_GF2m_simple_point_get_affine_coordinates,
102 ec_GF2m_simple_invert,
103 ec_GF2m_simple_is_at_infinity,
104 ec_GF2m_simple_is_on_curve,
106 ec_GF2m_simple_make_affine,
107 ec_GF2m_simple_points_make_affine,
109 /* the following three method functions are defined in ec2_mult.c */
111 ec_GF2m_precompute_mult,
112 ec_GF2m_have_precompute_mult,
114 ec_GF2m_simple_field_mul,
115 ec_GF2m_simple_field_sqr,
116 ec_GF2m_simple_field_div,
117 0 /* field_encode */,
118 0 /* field_decode */,
119 0 /* field_set_to_one */ };
125 /* Initialize a GF(2^m)-based EC_GROUP structure.
126 * Note that all other members are handled by EC_GROUP_new.
128 int ec_GF2m_simple_group_init(EC_GROUP *group)
130 BN_init(&group->field);
137 /* Free a GF(2^m)-based EC_GROUP structure.
138 * Note that all other members are handled by EC_GROUP_free.
140 void ec_GF2m_simple_group_finish(EC_GROUP *group)
142 BN_free(&group->field);
148 /* Clear and free a GF(2^m)-based EC_GROUP structure.
149 * Note that all other members are handled by EC_GROUP_clear_free.
151 void ec_GF2m_simple_group_clear_finish(EC_GROUP *group)
153 BN_clear_free(&group->field);
154 BN_clear_free(&group->a);
155 BN_clear_free(&group->b);
165 /* Copy a GF(2^m)-based EC_GROUP structure.
166 * Note that all other members are handled by EC_GROUP_copy.
168 int ec_GF2m_simple_group_copy(EC_GROUP *dest, const EC_GROUP *src)
171 if (!BN_copy(&dest->field, &src->field)) return 0;
172 if (!BN_copy(&dest->a, &src->a)) return 0;
173 if (!BN_copy(&dest->b, &src->b)) return 0;
174 dest->poly[0] = src->poly[0];
175 dest->poly[1] = src->poly[1];
176 dest->poly[2] = src->poly[2];
177 dest->poly[3] = src->poly[3];
178 dest->poly[4] = src->poly[4];
179 dest->poly[5] = src->poly[5];
180 if (bn_wexpand(&dest->a, (int)(dest->poly[0] + BN_BITS2 - 1) / BN_BITS2) == NULL) return 0;
181 if (bn_wexpand(&dest->b, (int)(dest->poly[0] + BN_BITS2 - 1) / BN_BITS2) == NULL) return 0;
182 for (i = dest->a.top; i < dest->a.dmax; i++) dest->a.d[i] = 0;
183 for (i = dest->b.top; i < dest->b.dmax; i++) dest->b.d[i] = 0;
188 /* Set the curve parameters of an EC_GROUP structure. */
189 int ec_GF2m_simple_group_set_curve(EC_GROUP *group,
190 const BIGNUM *p, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
195 if (!BN_copy(&group->field, p)) goto err;
196 i = BN_GF2m_poly2arr(&group->field, group->poly, 6) - 1;
197 if ((i != 5) && (i != 3))
199 ECerr(EC_F_EC_GF2M_SIMPLE_GROUP_SET_CURVE, EC_R_UNSUPPORTED_FIELD);
204 if (!BN_GF2m_mod_arr(&group->a, a, group->poly)) goto err;
205 if(bn_wexpand(&group->a, (int)(group->poly[0] + BN_BITS2 - 1) / BN_BITS2) == NULL) goto err;
206 for (i = group->a.top; i < group->a.dmax; i++) group->a.d[i] = 0;
209 if (!BN_GF2m_mod_arr(&group->b, b, group->poly)) goto err;
210 if(bn_wexpand(&group->b, (int)(group->poly[0] + BN_BITS2 - 1) / BN_BITS2) == NULL) goto err;
211 for (i = group->b.top; i < group->b.dmax; i++) group->b.d[i] = 0;
219 /* Get the curve parameters of an EC_GROUP structure.
220 * If p, a, or b are NULL then there values will not be set but the method will return with success.
222 int ec_GF2m_simple_group_get_curve(const EC_GROUP *group, BIGNUM *p, BIGNUM *a, BIGNUM *b, BN_CTX *ctx)
228 if (!BN_copy(p, &group->field)) return 0;
233 if (!BN_copy(a, &group->a)) goto err;
238 if (!BN_copy(b, &group->b)) goto err;
248 /* Gets the degree of the field. For a curve over GF(2^m) this is the value m. */
249 int ec_GF2m_simple_group_get_degree(const EC_GROUP *group)
251 return BN_num_bits(&group->field)-1;
255 /* Checks the discriminant of the curve.
256 * y^2 + x*y = x^3 + a*x^2 + b is an elliptic curve <=> b != 0 (mod p)
258 int ec_GF2m_simple_group_check_discriminant(const EC_GROUP *group, BN_CTX *ctx)
262 BN_CTX *new_ctx = NULL;
266 ctx = new_ctx = BN_CTX_new();
269 ECerr(EC_F_EC_GF2M_SIMPLE_GROUP_CHECK_DISCRIMINANT, ERR_R_MALLOC_FAILURE);
275 if (b == NULL) goto err;
277 if (!BN_GF2m_mod_arr(b, &group->b, group->poly)) goto err;
279 /* check the discriminant:
280 * y^2 + x*y = x^3 + a*x^2 + b is an elliptic curve <=> b != 0 (mod p)
282 if (BN_is_zero(b)) goto err;
290 BN_CTX_free(new_ctx);
295 /* Initializes an EC_POINT. */
296 int ec_GF2m_simple_point_init(EC_POINT *point)
305 /* Frees an EC_POINT. */
306 void ec_GF2m_simple_point_finish(EC_POINT *point)
314 /* Clears and frees an EC_POINT. */
315 void ec_GF2m_simple_point_clear_finish(EC_POINT *point)
317 BN_clear_free(&point->X);
318 BN_clear_free(&point->Y);
319 BN_clear_free(&point->Z);
324 /* Copy the contents of one EC_POINT into another. Assumes dest is initialized. */
325 int ec_GF2m_simple_point_copy(EC_POINT *dest, const EC_POINT *src)
327 if (!BN_copy(&dest->X, &src->X)) return 0;
328 if (!BN_copy(&dest->Y, &src->Y)) return 0;
329 if (!BN_copy(&dest->Z, &src->Z)) return 0;
330 dest->Z_is_one = src->Z_is_one;
336 /* Set an EC_POINT to the point at infinity.
337 * A point at infinity is represented by having Z=0.
339 int ec_GF2m_simple_point_set_to_infinity(const EC_GROUP *group, EC_POINT *point)
347 /* Set the coordinates of an EC_POINT using affine coordinates.
348 * Note that the simple implementation only uses affine coordinates.
350 int ec_GF2m_simple_point_set_affine_coordinates(const EC_GROUP *group, EC_POINT *point,
351 const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx)
354 if (x == NULL || y == NULL)
356 ECerr(EC_F_EC_GF2M_SIMPLE_POINT_SET_AFFINE_COORDINATES, ERR_R_PASSED_NULL_PARAMETER);
360 if (!BN_copy(&point->X, x)) goto err;
361 BN_set_negative(&point->X, 0);
362 if (!BN_copy(&point->Y, y)) goto err;
363 BN_set_negative(&point->Y, 0);
364 if (!BN_copy(&point->Z, BN_value_one())) goto err;
365 BN_set_negative(&point->Z, 0);
374 /* Gets the affine coordinates of an EC_POINT.
375 * Note that the simple implementation only uses affine coordinates.
377 int ec_GF2m_simple_point_get_affine_coordinates(const EC_GROUP *group, const EC_POINT *point,
378 BIGNUM *x, BIGNUM *y, BN_CTX *ctx)
382 if (EC_POINT_is_at_infinity(group, point))
384 ECerr(EC_F_EC_GF2M_SIMPLE_POINT_GET_AFFINE_COORDINATES, EC_R_POINT_AT_INFINITY);
388 if (BN_cmp(&point->Z, BN_value_one()))
390 ECerr(EC_F_EC_GF2M_SIMPLE_POINT_GET_AFFINE_COORDINATES, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
395 if (!BN_copy(x, &point->X)) goto err;
396 BN_set_negative(x, 0);
400 if (!BN_copy(y, &point->Y)) goto err;
401 BN_set_negative(y, 0);
409 /* Computes a + b and stores the result in r. r could be a or b, a could be b.
410 * Uses algorithm A.10.2 of IEEE P1363.
412 int ec_GF2m_simple_add(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a, const EC_POINT *b, BN_CTX *ctx)
414 BN_CTX *new_ctx = NULL;
415 BIGNUM *x0, *y0, *x1, *y1, *x2, *y2, *s, *t;
418 if (EC_POINT_is_at_infinity(group, a))
420 if (!EC_POINT_copy(r, b)) return 0;
424 if (EC_POINT_is_at_infinity(group, b))
426 if (!EC_POINT_copy(r, a)) return 0;
432 ctx = new_ctx = BN_CTX_new();
438 x0 = BN_CTX_get(ctx);
439 y0 = BN_CTX_get(ctx);
440 x1 = BN_CTX_get(ctx);
441 y1 = BN_CTX_get(ctx);
442 x2 = BN_CTX_get(ctx);
443 y2 = BN_CTX_get(ctx);
446 if (t == NULL) goto err;
450 if (!BN_copy(x0, &a->X)) goto err;
451 if (!BN_copy(y0, &a->Y)) goto err;
455 if (!EC_POINT_get_affine_coordinates_GF2m(group, a, x0, y0, ctx)) goto err;
459 if (!BN_copy(x1, &b->X)) goto err;
460 if (!BN_copy(y1, &b->Y)) goto err;
464 if (!EC_POINT_get_affine_coordinates_GF2m(group, b, x1, y1, ctx)) goto err;
468 if (BN_GF2m_cmp(x0, x1))
470 if (!BN_GF2m_add(t, x0, x1)) goto err;
471 if (!BN_GF2m_add(s, y0, y1)) goto err;
472 if (!group->meth->field_div(group, s, s, t, ctx)) goto err;
473 if (!group->meth->field_sqr(group, x2, s, ctx)) goto err;
474 if (!BN_GF2m_add(x2, x2, &group->a)) goto err;
475 if (!BN_GF2m_add(x2, x2, s)) goto err;
476 if (!BN_GF2m_add(x2, x2, t)) goto err;
480 if (BN_GF2m_cmp(y0, y1) || BN_is_zero(x1))
482 if (!EC_POINT_set_to_infinity(group, r)) goto err;
486 if (!group->meth->field_div(group, s, y1, x1, ctx)) goto err;
487 if (!BN_GF2m_add(s, s, x1)) goto err;
489 if (!group->meth->field_sqr(group, x2, s, ctx)) goto err;
490 if (!BN_GF2m_add(x2, x2, s)) goto err;
491 if (!BN_GF2m_add(x2, x2, &group->a)) goto err;
494 if (!BN_GF2m_add(y2, x1, x2)) goto err;
495 if (!group->meth->field_mul(group, y2, y2, s, ctx)) goto err;
496 if (!BN_GF2m_add(y2, y2, x2)) goto err;
497 if (!BN_GF2m_add(y2, y2, y1)) goto err;
499 if (!EC_POINT_set_affine_coordinates_GF2m(group, r, x2, y2, ctx)) goto err;
506 BN_CTX_free(new_ctx);
511 /* Computes 2 * a and stores the result in r. r could be a.
512 * Uses algorithm A.10.2 of IEEE P1363.
514 int ec_GF2m_simple_dbl(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a, BN_CTX *ctx)
516 return ec_GF2m_simple_add(group, r, a, a, ctx);
520 int ec_GF2m_simple_invert(const EC_GROUP *group, EC_POINT *point, BN_CTX *ctx)
522 if (EC_POINT_is_at_infinity(group, point) || BN_is_zero(&point->Y))
523 /* point is its own inverse */
526 if (!EC_POINT_make_affine(group, point, ctx)) return 0;
527 return BN_GF2m_add(&point->Y, &point->X, &point->Y);
531 /* Indicates whether the given point is the point at infinity. */
532 int ec_GF2m_simple_is_at_infinity(const EC_GROUP *group, const EC_POINT *point)
534 return BN_is_zero(&point->Z);
538 /* Determines whether the given EC_POINT is an actual point on the curve defined
539 * in the EC_GROUP. A point is valid if it satisfies the Weierstrass equation:
540 * y^2 + x*y = x^3 + a*x^2 + b.
542 int ec_GF2m_simple_is_on_curve(const EC_GROUP *group, const EC_POINT *point, BN_CTX *ctx)
545 BN_CTX *new_ctx = NULL;
547 int (*field_mul)(const EC_GROUP *, BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
548 int (*field_sqr)(const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
550 if (EC_POINT_is_at_infinity(group, point))
553 field_mul = group->meth->field_mul;
554 field_sqr = group->meth->field_sqr;
556 /* only support affine coordinates */
557 if (!point->Z_is_one) goto err;
561 ctx = new_ctx = BN_CTX_new();
567 y2 = BN_CTX_get(ctx);
568 lh = BN_CTX_get(ctx);
569 if (lh == NULL) goto err;
571 /* We have a curve defined by a Weierstrass equation
572 * y^2 + x*y = x^3 + a*x^2 + b.
573 * <=> x^3 + a*x^2 + x*y + b + y^2 = 0
574 * <=> ((x + a) * x + y ) * x + b + y^2 = 0
576 if (!BN_GF2m_add(lh, &point->X, &group->a)) goto err;
577 if (!field_mul(group, lh, lh, &point->X, ctx)) goto err;
578 if (!BN_GF2m_add(lh, lh, &point->Y)) goto err;
579 if (!field_mul(group, lh, lh, &point->X, ctx)) goto err;
580 if (!BN_GF2m_add(lh, lh, &group->b)) goto err;
581 if (!field_sqr(group, y2, &point->Y, ctx)) goto err;
582 if (!BN_GF2m_add(lh, lh, y2)) goto err;
583 ret = BN_is_zero(lh);
585 if (ctx) BN_CTX_end(ctx);
586 if (new_ctx) BN_CTX_free(new_ctx);
591 /* Indicates whether two points are equal.
594 * 0 equal (in affine coordinates)
597 int ec_GF2m_simple_cmp(const EC_GROUP *group, const EC_POINT *a, const EC_POINT *b, BN_CTX *ctx)
599 BIGNUM *aX, *aY, *bX, *bY;
600 BN_CTX *new_ctx = NULL;
603 if (EC_POINT_is_at_infinity(group, a))
605 return EC_POINT_is_at_infinity(group, b) ? 0 : 1;
608 if (EC_POINT_is_at_infinity(group, b))
611 if (a->Z_is_one && b->Z_is_one)
613 return ((BN_cmp(&a->X, &b->X) == 0) && BN_cmp(&a->Y, &b->Y) == 0) ? 0 : 1;
618 ctx = new_ctx = BN_CTX_new();
624 aX = BN_CTX_get(ctx);
625 aY = BN_CTX_get(ctx);
626 bX = BN_CTX_get(ctx);
627 bY = BN_CTX_get(ctx);
628 if (bY == NULL) goto err;
630 if (!EC_POINT_get_affine_coordinates_GF2m(group, a, aX, aY, ctx)) goto err;
631 if (!EC_POINT_get_affine_coordinates_GF2m(group, b, bX, bY, ctx)) goto err;
632 ret = ((BN_cmp(aX, bX) == 0) && BN_cmp(aY, bY) == 0) ? 0 : 1;
635 if (ctx) BN_CTX_end(ctx);
636 if (new_ctx) BN_CTX_free(new_ctx);
641 /* Forces the given EC_POINT to internally use affine coordinates. */
642 int ec_GF2m_simple_make_affine(const EC_GROUP *group, EC_POINT *point, BN_CTX *ctx)
644 BN_CTX *new_ctx = NULL;
648 if (point->Z_is_one || EC_POINT_is_at_infinity(group, point))
653 ctx = new_ctx = BN_CTX_new();
661 if (y == NULL) goto err;
663 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
664 if (!BN_copy(&point->X, x)) goto err;
665 if (!BN_copy(&point->Y, y)) goto err;
666 if (!BN_one(&point->Z)) goto err;
671 if (ctx) BN_CTX_end(ctx);
672 if (new_ctx) BN_CTX_free(new_ctx);
677 /* Forces each of the EC_POINTs in the given array to use affine coordinates. */
678 int ec_GF2m_simple_points_make_affine(const EC_GROUP *group, size_t num, EC_POINT *points[], BN_CTX *ctx)
682 for (i = 0; i < num; i++)
684 if (!group->meth->make_affine(group, points[i], ctx)) return 0;
691 /* Wrapper to simple binary polynomial field multiplication implementation. */
692 int ec_GF2m_simple_field_mul(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
694 return BN_GF2m_mod_mul_arr(r, a, b, group->poly, ctx);
698 /* Wrapper to simple binary polynomial field squaring implementation. */
699 int ec_GF2m_simple_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
701 return BN_GF2m_mod_sqr_arr(r, a, group->poly, ctx);
705 /* Wrapper to simple binary polynomial field division implementation. */
706 int ec_GF2m_simple_field_div(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
708 return BN_GF2m_mod_div(r, a, b, &group->field, ctx);