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bn_mod.c (302408) bn_mod.c (337982)
1/* crypto/bn/bn_mod.c */
2/*
3 * Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
4 * for the OpenSSL project.
5 */
6/* ====================================================================
1/* crypto/bn/bn_mod.c */
2/*
3 * Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
4 * for the OpenSSL project.
5 */
6/* ====================================================================
7 * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
7 * Copyright (c) 1998-2018 The OpenSSL Project. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *

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144{
145 if (!BN_add(r, a, b))
146 return 0;
147 return BN_nnmod(r, r, m, ctx);
148}
149
150/*
151 * BN_mod_add variant that may be used if both a and b are non-negative and
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *

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144{
145 if (!BN_add(r, a, b))
146 return 0;
147 return BN_nnmod(r, r, m, ctx);
148}
149
150/*
151 * BN_mod_add variant that may be used if both a and b are non-negative and
152 * less than m
152 * less than m. The original algorithm was
153 *
154 * if (!BN_uadd(r, a, b))
155 * return 0;
156 * if (BN_ucmp(r, m) >= 0)
157 * return BN_usub(r, r, m);
158 *
159 * which is replaced with addition, subtracting modulus, and conditional
160 * move depending on whether or not subtraction borrowed.
153 */
161 */
154int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
155 const BIGNUM *m)
162int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
163 const BIGNUM *m)
156{
164{
157 if (!BN_uadd(r, a, b))
165 size_t i, ai, bi, mtop = m->top;
166 BN_ULONG storage[1024 / BN_BITS2];
167 BN_ULONG carry, temp, mask, *rp, *tp = storage;
168 const BN_ULONG *ap, *bp;
169
170 if (bn_wexpand(r, m->top) == NULL)
158 return 0;
171 return 0;
159 if (BN_ucmp(r, m) >= 0)
160 return BN_usub(r, r, m);
172
173 if (mtop > sizeof(storage) / sizeof(storage[0])
174 && (tp = OPENSSL_malloc(mtop * sizeof(BN_ULONG))) == NULL)
175 return 0;
176
177 ap = a->d != NULL ? a->d : tp;
178 bp = b->d != NULL ? b->d : tp;
179
180 for (i = 0, ai = 0, bi = 0, carry = 0; i < mtop;) {
181 mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1));
182 temp = ((ap[ai] & mask) + carry) & BN_MASK2;
183 carry = (temp < carry);
184
185 mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1));
186 tp[i] = ((bp[bi] & mask) + temp) & BN_MASK2;
187 carry += (tp[i] < temp);
188
189 i++;
190 ai += (i - a->dmax) >> (8 * sizeof(i) - 1);
191 bi += (i - b->dmax) >> (8 * sizeof(i) - 1);
192 }
193 rp = r->d;
194 carry -= bn_sub_words(rp, tp, m->d, mtop);
195 for (i = 0; i < mtop; i++) {
196 rp[i] = (carry & tp[i]) | (~carry & rp[i]);
197 ((volatile BN_ULONG *)tp)[i] = 0;
198 }
199 r->top = mtop;
200 r->neg = 0;
201
202 if (tp != storage)
203 OPENSSL_free(tp);
204
161 return 1;
162}
163
205 return 1;
206}
207
208int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
209 const BIGNUM *m)
210{
211 int ret = bn_mod_add_fixed_top(r, a, b, m);
212
213 if (ret)
214 bn_correct_top(r);
215
216 return ret;
217}
218
164int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
165 BN_CTX *ctx)
166{
167 if (!BN_sub(r, a, b))
168 return 0;
169 return BN_nnmod(r, r, m, ctx);
170}
171

--- 145 unchanged lines hidden --- 		219int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
220 BN_CTX *ctx)
221{
222 if (!BN_sub(r, a, b))
223 return 0;
224 return BN_nnmod(r, r, m, ctx);
225}
226

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