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1 | /* crypto/ec/ec2_smpt.c */ |
2 | /* This code was originally written by Douglas Stebila | |
3 | * <dstebila@student.math.uwaterloo.ca> for the OpenSSL project. | |
4 | */ | |
5 | /* ==================================================================== | |
6 | * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved. | |
7 | * | |
8 | * Redistribution and use in source and binary forms, with or without | |
9 | * modification, are permitted provided that the following conditions | |
10 | * are met: | |
11 | * | |
12 | * 1. Redistributions of source code must retain the above copyright | |
13 | * notice, this list of conditions and the following disclaimer. | |
14 | * | |
15 | * 2. Redistributions in binary form must reproduce the above copyright | |
16 | * notice, this list of conditions and the following disclaimer in | |
17 | * the documentation and/or other materials provided with the | |
18 | * distribution. | |
19 | * | |
20 | * 3. All advertising materials mentioning features or use of this | |
21 | * software must display the following acknowledgment: | |
22 | * "This product includes software developed by the OpenSSL Project | |
23 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
24 | * | |
25 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
26 | * endorse or promote products derived from this software without | |
27 | * prior written permission. For written permission, please contact | |
28 | * openssl-core@openssl.org. | |
29 | * | |
30 | * 5. Products derived from this software may not be called "OpenSSL" | |
31 | * nor may "OpenSSL" appear in their names without prior written | |
32 | * permission of the OpenSSL Project. | |
33 | * | |
34 | * 6. Redistributions of any form whatsoever must retain the following | |
35 | * acknowledgment: | |
36 | * "This product includes software developed by the OpenSSL Project | |
37 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
38 | * | |
39 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
40 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
41 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
42 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
43 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
44 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
45 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
46 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
47 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
48 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
49 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
50 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
51 | * ==================================================================== | |
52 | * | |
53 | * This product includes cryptographic software written by Eric Young | |
54 | * (eay@cryptsoft.com). This product includes software written by Tim | |
55 | * Hudson (tjh@cryptsoft.com). | |
56 | * | |
57 | */ | |
58 | ||
59 | ||
60 | /* Calaculates and sets the affine coordinates of an EC_POINT from the given | |
61 | * compressed coordinates. Uses algorithm 2.3.4 of SEC 1. | |
62 | * Note that the simple implementation only uses affine coordinates. | |
63 | * | |
64 | * This algorithm is patented by Certicom Corp. under US Patent 6,141,420. | |
65 | * This function is disabled by default and can be enabled by defining the | |
66 | * preprocessor macro OPENSSL_EC_BIN_PT_COMP at Configure-time. | |
67 | */ | |
35b73a1f | 68 | int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point, |
7793f30e BM |
69 | const BIGNUM *x_, int y_bit, BN_CTX *ctx) |
70 | { | |
71 | #ifndef OPENSSL_EC_BIN_PT_COMP | |
35b73a1f | 72 | ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_DISABLED); |
7793f30e BM |
73 | return 0; |
74 | #else | |
75 | BN_CTX *new_ctx = NULL; | |
76 | BIGNUM *tmp, *x, *y, *z; | |
77 | int ret = 0, z0; | |
78 | ||
79 | if (ctx == NULL) | |
80 | { | |
81 | ctx = new_ctx = BN_CTX_new(); | |
82 | if (ctx == NULL) | |
83 | return 0; | |
84 | } | |
85 | ||
86 | y_bit = (y_bit != 0) ? 1 : 0; | |
87 | ||
88 | BN_CTX_start(ctx); | |
89 | tmp = BN_CTX_get(ctx); | |
90 | x = BN_CTX_get(ctx); | |
91 | y = BN_CTX_get(ctx); | |
92 | z = BN_CTX_get(ctx); | |
93 | if (z == NULL) goto err; | |
94 | ||
95 | if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err; | |
96 | if (BN_is_zero(x)) | |
97 | { | |
98 | if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) goto err; | |
99 | } | |
100 | else | |
101 | { | |
102 | if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err; | |
103 | if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) goto err; | |
104 | if (!BN_GF2m_add(tmp, &group->a, tmp)) goto err; | |
105 | if (!BN_GF2m_add(tmp, x, tmp)) goto err; | |
106 | if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) goto err; | |
107 | z0 = (BN_is_odd(z)) ? 1 : 0; | |
108 | if (!group->meth->field_mul(group, y, x, z, ctx)) goto err; | |
109 | if (z0 != y_bit) | |
110 | { | |
111 | if (!BN_GF2m_add(y, y, x)) goto err; | |
112 | } | |
113 | } | |
114 | ||
115 | if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err; | |
116 | ||
117 | ret = 1; | |
118 | ||
119 | err: | |
120 | BN_CTX_end(ctx); | |
121 | if (new_ctx != NULL) | |
122 | BN_CTX_free(new_ctx); | |
123 | return ret; | |
124 | #endif | |
125 | } |