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Commit | Line | Data |
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4f22f405 | 1 | /* |
edea42c6 | 2 | * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved. |
dc434bbc | 3 | * |
367ace68 | 4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
4f22f405 RS |
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 | |
dc434bbc BM |
8 | */ |
9 | ||
dfeab068 | 10 | #include <stdio.h> |
b39fc560 | 11 | #include "internal/cryptlib.h" |
dfeab068 RE |
12 | #include "bn_lcl.h" |
13 | ||
0f113f3e | 14 | #define TABLE_SIZE 32 |
dfeab068 | 15 | |
020fc820 | 16 | int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, |
0f113f3e MC |
17 | const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m, |
18 | BN_CTX *ctx, BN_MONT_CTX *in_mont) | |
19 | { | |
20 | int i, j, bits, b, bits1, bits2, ret = | |
21 | 0, wpos1, wpos2, window1, window2, wvalue1, wvalue2; | |
22 | int r_is_one = 1; | |
23 | BIGNUM *d, *r; | |
24 | const BIGNUM *a_mod_m; | |
25 | /* Tables of variables obtained from 'ctx' */ | |
26 | BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE]; | |
27 | BN_MONT_CTX *mont = NULL; | |
28 | ||
29 | bn_check_top(a1); | |
30 | bn_check_top(p1); | |
31 | bn_check_top(a2); | |
32 | bn_check_top(p2); | |
33 | bn_check_top(m); | |
34 | ||
35 | if (!(m->d[0] & 1)) { | |
36 | BNerr(BN_F_BN_MOD_EXP2_MONT, BN_R_CALLED_WITH_EVEN_MODULUS); | |
26a7d938 | 37 | return 0; |
0f113f3e MC |
38 | } |
39 | bits1 = BN_num_bits(p1); | |
40 | bits2 = BN_num_bits(p2); | |
41 | if ((bits1 == 0) && (bits2 == 0)) { | |
42 | ret = BN_one(rr); | |
43 | return ret; | |
44 | } | |
dfeab068 | 45 | |
0f113f3e | 46 | bits = (bits1 > bits2) ? bits1 : bits2; |
dfeab068 | 47 | |
0f113f3e MC |
48 | BN_CTX_start(ctx); |
49 | d = BN_CTX_get(ctx); | |
50 | r = BN_CTX_get(ctx); | |
51 | val1[0] = BN_CTX_get(ctx); | |
52 | val2[0] = BN_CTX_get(ctx); | |
edea42c6 | 53 | if (val2[0] == NULL) |
0f113f3e | 54 | goto err; |
9b141126 | 55 | |
0f113f3e MC |
56 | if (in_mont != NULL) |
57 | mont = in_mont; | |
58 | else { | |
59 | if ((mont = BN_MONT_CTX_new()) == NULL) | |
60 | goto err; | |
61 | if (!BN_MONT_CTX_set(mont, m, ctx)) | |
62 | goto err; | |
63 | } | |
9b141126 | 64 | |
0f113f3e MC |
65 | window1 = BN_window_bits_for_exponent_size(bits1); |
66 | window2 = BN_window_bits_for_exponent_size(bits2); | |
dfeab068 | 67 | |
0f113f3e MC |
68 | /* |
69 | * Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1) | |
70 | */ | |
71 | if (a1->neg || BN_ucmp(a1, m) >= 0) { | |
72 | if (!BN_mod(val1[0], a1, m, ctx)) | |
73 | goto err; | |
74 | a_mod_m = val1[0]; | |
75 | } else | |
76 | a_mod_m = a1; | |
77 | if (BN_is_zero(a_mod_m)) { | |
78 | BN_zero(rr); | |
79 | ret = 1; | |
80 | goto err; | |
81 | } | |
dc434bbc | 82 | |
0f113f3e MC |
83 | if (!BN_to_montgomery(val1[0], a_mod_m, mont, ctx)) |
84 | goto err; | |
85 | if (window1 > 1) { | |
86 | if (!BN_mod_mul_montgomery(d, val1[0], val1[0], mont, ctx)) | |
87 | goto err; | |
73c2522c | 88 | |
0f113f3e MC |
89 | j = 1 << (window1 - 1); |
90 | for (i = 1; i < j; i++) { | |
91 | if (((val1[i] = BN_CTX_get(ctx)) == NULL) || | |
92 | !BN_mod_mul_montgomery(val1[i], val1[i - 1], d, mont, ctx)) | |
93 | goto err; | |
94 | } | |
95 | } | |
dc434bbc | 96 | |
0f113f3e MC |
97 | /* |
98 | * Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1) | |
99 | */ | |
100 | if (a2->neg || BN_ucmp(a2, m) >= 0) { | |
101 | if (!BN_mod(val2[0], a2, m, ctx)) | |
102 | goto err; | |
103 | a_mod_m = val2[0]; | |
104 | } else | |
105 | a_mod_m = a2; | |
106 | if (BN_is_zero(a_mod_m)) { | |
107 | BN_zero(rr); | |
108 | ret = 1; | |
109 | goto err; | |
110 | } | |
111 | if (!BN_to_montgomery(val2[0], a_mod_m, mont, ctx)) | |
112 | goto err; | |
113 | if (window2 > 1) { | |
114 | if (!BN_mod_mul_montgomery(d, val2[0], val2[0], mont, ctx)) | |
115 | goto err; | |
dc434bbc | 116 | |
0f113f3e MC |
117 | j = 1 << (window2 - 1); |
118 | for (i = 1; i < j; i++) { | |
119 | if (((val2[i] = BN_CTX_get(ctx)) == NULL) || | |
120 | !BN_mod_mul_montgomery(val2[i], val2[i - 1], d, mont, ctx)) | |
121 | goto err; | |
122 | } | |
123 | } | |
dc434bbc | 124 | |
0f113f3e MC |
125 | /* Now compute the power product, using independent windows. */ |
126 | r_is_one = 1; | |
127 | wvalue1 = 0; /* The 'value' of the first window */ | |
128 | wvalue2 = 0; /* The 'value' of the second window */ | |
129 | wpos1 = 0; /* If wvalue1 > 0, the bottom bit of the | |
130 | * first window */ | |
131 | wpos2 = 0; /* If wvalue2 > 0, the bottom bit of the | |
132 | * second window */ | |
dc434bbc | 133 | |
0f113f3e MC |
134 | if (!BN_to_montgomery(r, BN_value_one(), mont, ctx)) |
135 | goto err; | |
136 | for (b = bits - 1; b >= 0; b--) { | |
137 | if (!r_is_one) { | |
138 | if (!BN_mod_mul_montgomery(r, r, r, mont, ctx)) | |
139 | goto err; | |
140 | } | |
dc434bbc | 141 | |
0f113f3e MC |
142 | if (!wvalue1) |
143 | if (BN_is_bit_set(p1, b)) { | |
144 | /* | |
145 | * consider bits b-window1+1 .. b for this window | |
146 | */ | |
147 | i = b - window1 + 1; | |
148 | while (!BN_is_bit_set(p1, i)) /* works for i<0 */ | |
149 | i++; | |
150 | wpos1 = i; | |
151 | wvalue1 = 1; | |
152 | for (i = b - 1; i >= wpos1; i--) { | |
153 | wvalue1 <<= 1; | |
154 | if (BN_is_bit_set(p1, i)) | |
155 | wvalue1++; | |
156 | } | |
157 | } | |
dc434bbc | 158 | |
0f113f3e MC |
159 | if (!wvalue2) |
160 | if (BN_is_bit_set(p2, b)) { | |
161 | /* | |
162 | * consider bits b-window2+1 .. b for this window | |
163 | */ | |
164 | i = b - window2 + 1; | |
165 | while (!BN_is_bit_set(p2, i)) | |
166 | i++; | |
167 | wpos2 = i; | |
168 | wvalue2 = 1; | |
169 | for (i = b - 1; i >= wpos2; i--) { | |
170 | wvalue2 <<= 1; | |
171 | if (BN_is_bit_set(p2, i)) | |
172 | wvalue2++; | |
173 | } | |
174 | } | |
dc434bbc | 175 | |
0f113f3e MC |
176 | if (wvalue1 && b == wpos1) { |
177 | /* wvalue1 is odd and < 2^window1 */ | |
178 | if (!BN_mod_mul_montgomery(r, r, val1[wvalue1 >> 1], mont, ctx)) | |
179 | goto err; | |
180 | wvalue1 = 0; | |
181 | r_is_one = 0; | |
182 | } | |
dc434bbc | 183 | |
0f113f3e MC |
184 | if (wvalue2 && b == wpos2) { |
185 | /* wvalue2 is odd and < 2^window2 */ | |
186 | if (!BN_mod_mul_montgomery(r, r, val2[wvalue2 >> 1], mont, ctx)) | |
187 | goto err; | |
188 | wvalue2 = 0; | |
189 | r_is_one = 0; | |
190 | } | |
191 | } | |
192 | if (!BN_from_montgomery(rr, r, mont, ctx)) | |
193 | goto err; | |
194 | ret = 1; | |
195 | err: | |
23a1d5e9 | 196 | if (in_mont == NULL) |
0f113f3e MC |
197 | BN_MONT_CTX_free(mont); |
198 | BN_CTX_end(ctx); | |
199 | bn_check_top(rr); | |
26a7d938 | 200 | return ret; |
0f113f3e | 201 | } |