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0f113f3e | 1 | /* |
4f22f405 | 2 | * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved. |
7b1a0451 | 3 | * |
4f22f405 RS |
4 | * Licensed under the OpenSSL license (the "License"). You may not use |
5 | * this file except in compliance with the License. You can obtain a copy | |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
7b1a0451 DSH |
8 | */ |
9 | ||
10 | #include <stdio.h> | |
11 | #include <openssl/bn.h> | |
85bcf27c | 12 | #include "bn_lcl.h" |
7b1a0451 DSH |
13 | |
14 | /* X9.31 routines for prime derivation */ | |
15 | ||
0f113f3e MC |
16 | /* |
17 | * X9.31 prime derivation. This is used to generate the primes pi (p1, p2, | |
18 | * q1, q2) from a parameter Xpi by checking successive odd integers. | |
7b1a0451 DSH |
19 | */ |
20 | ||
21 | static int bn_x931_derive_pi(BIGNUM *pi, const BIGNUM *Xpi, BN_CTX *ctx, | |
0f113f3e MC |
22 | BN_GENCB *cb) |
23 | { | |
24 | int i = 0; | |
25 | if (!BN_copy(pi, Xpi)) | |
26 | return 0; | |
27 | if (!BN_is_odd(pi) && !BN_add_word(pi, 1)) | |
28 | return 0; | |
29 | for (;;) { | |
30 | i++; | |
31 | BN_GENCB_call(cb, 0, i); | |
0d4fb843 | 32 | /* NB 27 MR is specified in X9.31 */ |
0f113f3e MC |
33 | if (BN_is_prime_fasttest_ex(pi, 27, ctx, 1, cb)) |
34 | break; | |
35 | if (!BN_add_word(pi, 2)) | |
36 | return 0; | |
37 | } | |
38 | BN_GENCB_call(cb, 2, i); | |
39 | return 1; | |
40 | } | |
41 | ||
42 | /* | |
43 | * This is the main X9.31 prime derivation function. From parameters Xp1, Xp2 | |
44 | * and Xp derive the prime p. If the parameters p1 or p2 are not NULL they | |
45 | * will be returned too: this is needed for testing. | |
7b1a0451 DSH |
46 | */ |
47 | ||
48 | int BN_X931_derive_prime_ex(BIGNUM *p, BIGNUM *p1, BIGNUM *p2, | |
0f113f3e MC |
49 | const BIGNUM *Xp, const BIGNUM *Xp1, |
50 | const BIGNUM *Xp2, const BIGNUM *e, BN_CTX *ctx, | |
51 | BN_GENCB *cb) | |
52 | { | |
53 | int ret = 0; | |
7b1a0451 | 54 | |
0f113f3e | 55 | BIGNUM *t, *p1p2, *pm1; |
7b1a0451 | 56 | |
0f113f3e MC |
57 | /* Only even e supported */ |
58 | if (!BN_is_odd(e)) | |
59 | return 0; | |
7b1a0451 | 60 | |
0f113f3e MC |
61 | BN_CTX_start(ctx); |
62 | if (!p1) | |
63 | p1 = BN_CTX_get(ctx); | |
7b1a0451 | 64 | |
0f113f3e MC |
65 | if (!p2) |
66 | p2 = BN_CTX_get(ctx); | |
7b1a0451 | 67 | |
0f113f3e | 68 | t = BN_CTX_get(ctx); |
7b1a0451 | 69 | |
0f113f3e | 70 | p1p2 = BN_CTX_get(ctx); |
7b1a0451 | 71 | |
0f113f3e | 72 | pm1 = BN_CTX_get(ctx); |
7b1a0451 | 73 | |
0f113f3e MC |
74 | if (!bn_x931_derive_pi(p1, Xp1, ctx, cb)) |
75 | goto err; | |
7b1a0451 | 76 | |
0f113f3e MC |
77 | if (!bn_x931_derive_pi(p2, Xp2, ctx, cb)) |
78 | goto err; | |
7b1a0451 | 79 | |
0f113f3e MC |
80 | if (!BN_mul(p1p2, p1, p2, ctx)) |
81 | goto err; | |
7b1a0451 | 82 | |
0f113f3e | 83 | /* First set p to value of Rp */ |
7b1a0451 | 84 | |
0f113f3e MC |
85 | if (!BN_mod_inverse(p, p2, p1, ctx)) |
86 | goto err; | |
7b1a0451 | 87 | |
0f113f3e MC |
88 | if (!BN_mul(p, p, p2, ctx)) |
89 | goto err; | |
7b1a0451 | 90 | |
0f113f3e MC |
91 | if (!BN_mod_inverse(t, p1, p2, ctx)) |
92 | goto err; | |
7b1a0451 | 93 | |
0f113f3e MC |
94 | if (!BN_mul(t, t, p1, ctx)) |
95 | goto err; | |
7b1a0451 | 96 | |
0f113f3e MC |
97 | if (!BN_sub(p, p, t)) |
98 | goto err; | |
7b1a0451 | 99 | |
0f113f3e MC |
100 | if (p->neg && !BN_add(p, p, p1p2)) |
101 | goto err; | |
7b1a0451 | 102 | |
0f113f3e | 103 | /* p now equals Rp */ |
7b1a0451 | 104 | |
0f113f3e MC |
105 | if (!BN_mod_sub(p, p, Xp, p1p2, ctx)) |
106 | goto err; | |
7b1a0451 | 107 | |
0f113f3e MC |
108 | if (!BN_add(p, p, Xp)) |
109 | goto err; | |
7b1a0451 | 110 | |
0f113f3e | 111 | /* p now equals Yp0 */ |
7b1a0451 | 112 | |
0f113f3e MC |
113 | for (;;) { |
114 | int i = 1; | |
115 | BN_GENCB_call(cb, 0, i++); | |
116 | if (!BN_copy(pm1, p)) | |
117 | goto err; | |
118 | if (!BN_sub_word(pm1, 1)) | |
119 | goto err; | |
120 | if (!BN_gcd(t, pm1, e, ctx)) | |
121 | goto err; | |
122 | if (BN_is_one(t) | |
123 | /* | |
124 | * X9.31 specifies 8 MR and 1 Lucas test or any prime test | |
125 | * offering similar or better guarantees 50 MR is considerably | |
126 | * better. | |
127 | */ | |
128 | && BN_is_prime_fasttest_ex(p, 50, ctx, 1, cb)) | |
129 | break; | |
130 | if (!BN_add(p, p, p1p2)) | |
131 | goto err; | |
132 | } | |
7b1a0451 | 133 | |
0f113f3e | 134 | BN_GENCB_call(cb, 3, 0); |
7b1a0451 | 135 | |
0f113f3e | 136 | ret = 1; |
7b1a0451 | 137 | |
0f113f3e | 138 | err: |
7b1a0451 | 139 | |
0f113f3e | 140 | BN_CTX_end(ctx); |
7b1a0451 | 141 | |
0f113f3e MC |
142 | return ret; |
143 | } | |
7b1a0451 | 144 | |
0f113f3e MC |
145 | /* |
146 | * Generate pair of parameters Xp, Xq for X9.31 prime generation. Note: nbits | |
147 | * parameter is sum of number of bits in both. | |
7b1a0451 DSH |
148 | */ |
149 | ||
150 | int BN_X931_generate_Xpq(BIGNUM *Xp, BIGNUM *Xq, int nbits, BN_CTX *ctx) | |
0f113f3e MC |
151 | { |
152 | BIGNUM *t; | |
153 | int i; | |
154 | /* | |
155 | * Number of bits for each prime is of the form 512+128s for s = 0, 1, | |
156 | * ... | |
157 | */ | |
158 | if ((nbits < 1024) || (nbits & 0xff)) | |
159 | return 0; | |
160 | nbits >>= 1; | |
161 | /* | |
162 | * The random value Xp must be between sqrt(2) * 2^(nbits-1) and 2^nbits | |
163 | * - 1. By setting the top two bits we ensure that the lower bound is | |
164 | * exceeded. | |
165 | */ | |
166 | if (!BN_rand(Xp, nbits, 1, 0)) | |
3f6c7691 | 167 | goto err; |
0f113f3e MC |
168 | |
169 | BN_CTX_start(ctx); | |
170 | t = BN_CTX_get(ctx); | |
171 | ||
172 | for (i = 0; i < 1000; i++) { | |
173 | if (!BN_rand(Xq, nbits, 1, 0)) | |
3f6c7691 | 174 | goto err; |
0f113f3e MC |
175 | /* Check that |Xp - Xq| > 2^(nbits - 100) */ |
176 | BN_sub(t, Xp, Xq); | |
177 | if (BN_num_bits(t) > (nbits - 100)) | |
178 | break; | |
179 | } | |
180 | ||
181 | BN_CTX_end(ctx); | |
182 | ||
183 | if (i < 1000) | |
184 | return 1; | |
185 | ||
186 | return 0; | |
187 | ||
3f6c7691 AG |
188 | err: |
189 | BN_CTX_end(ctx); | |
190 | return 0; | |
0f113f3e MC |
191 | } |
192 | ||
193 | /* | |
194 | * Generate primes using X9.31 algorithm. Of the values p, p1, p2, Xp1 and | |
195 | * Xp2 only 'p' needs to be non-NULL. If any of the others are not NULL the | |
196 | * relevant parameter will be stored in it. Due to the fact that |Xp - Xq| > | |
197 | * 2^(nbits - 100) must be satisfied Xp and Xq are generated using the | |
198 | * previous function and supplied as input. | |
7b1a0451 DSH |
199 | */ |
200 | ||
201 | int BN_X931_generate_prime_ex(BIGNUM *p, BIGNUM *p1, BIGNUM *p2, | |
0f113f3e MC |
202 | BIGNUM *Xp1, BIGNUM *Xp2, |
203 | const BIGNUM *Xp, | |
204 | const BIGNUM *e, BN_CTX *ctx, BN_GENCB *cb) | |
205 | { | |
206 | int ret = 0; | |
7b1a0451 | 207 | |
0f113f3e MC |
208 | BN_CTX_start(ctx); |
209 | if (!Xp1) | |
210 | Xp1 = BN_CTX_get(ctx); | |
211 | if (!Xp2) | |
212 | Xp2 = BN_CTX_get(ctx); | |
7b1a0451 | 213 | |
0f113f3e MC |
214 | if (!BN_rand(Xp1, 101, 0, 0)) |
215 | goto error; | |
216 | if (!BN_rand(Xp2, 101, 0, 0)) | |
217 | goto error; | |
218 | if (!BN_X931_derive_prime_ex(p, p1, p2, Xp, Xp1, Xp2, e, ctx, cb)) | |
219 | goto error; | |
7b1a0451 | 220 | |
0f113f3e | 221 | ret = 1; |
7b1a0451 | 222 | |
0f113f3e MC |
223 | error: |
224 | BN_CTX_end(ctx); | |
7b1a0451 | 225 | |
0f113f3e | 226 | return ret; |
7b1a0451 | 227 | |
0f113f3e | 228 | } |