1 /* $OpenBSD: rsa_blinding.c,v 1.1 2023/08/09 09:23:03 tb Exp $ */ 2 /* ==================================================================== 3 * Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in 14 * the documentation and/or other materials provided with the 15 * distribution. 16 * 17 * 3. All advertising materials mentioning features or use of this 18 * software must display the following acknowledgment: 19 * "This product includes software developed by the OpenSSL Project 20 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 21 * 22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 23 * endorse or promote products derived from this software without 24 * prior written permission. For written permission, please contact 25 * openssl-core@openssl.org. 26 * 27 * 5. Products derived from this software may not be called "OpenSSL" 28 * nor may "OpenSSL" appear in their names without prior written 29 * permission of the OpenSSL Project. 30 * 31 * 6. Redistributions of any form whatsoever must retain the following 32 * acknowledgment: 33 * "This product includes software developed by the OpenSSL Project 34 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 35 * 36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 39 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 47 * OF THE POSSIBILITY OF SUCH DAMAGE. 48 * ==================================================================== 49 * 50 * This product includes cryptographic software written by Eric Young 51 * (eay@cryptsoft.com). This product includes software written by Tim 52 * Hudson (tjh@cryptsoft.com). 53 * 54 */ 55 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 56 * All rights reserved. 57 * 58 * This package is an SSL implementation written 59 * by Eric Young (eay@cryptsoft.com). 60 * The implementation was written so as to conform with Netscapes SSL. 61 * 62 * This library is free for commercial and non-commercial use as long as 63 * the following conditions are aheared to. The following conditions 64 * apply to all code found in this distribution, be it the RC4, RSA, 65 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 66 * included with this distribution is covered by the same copyright terms 67 * except that the holder is Tim Hudson (tjh@cryptsoft.com). 68 * 69 * Copyright remains Eric Young's, and as such any Copyright notices in 70 * the code are not to be removed. 71 * If this package is used in a product, Eric Young should be given attribution 72 * as the author of the parts of the library used. 73 * This can be in the form of a textual message at program startup or 74 * in documentation (online or textual) provided with the package. 75 * 76 * Redistribution and use in source and binary forms, with or without 77 * modification, are permitted provided that the following conditions 78 * are met: 79 * 1. Redistributions of source code must retain the copyright 80 * notice, this list of conditions and the following disclaimer. 81 * 2. Redistributions in binary form must reproduce the above copyright 82 * notice, this list of conditions and the following disclaimer in the 83 * documentation and/or other materials provided with the distribution. 84 * 3. All advertising materials mentioning features or use of this software 85 * must display the following acknowledgement: 86 * "This product includes cryptographic software written by 87 * Eric Young (eay@cryptsoft.com)" 88 * The word 'cryptographic' can be left out if the rouines from the library 89 * being used are not cryptographic related :-). 90 * 4. If you include any Windows specific code (or a derivative thereof) from 91 * the apps directory (application code) you must include an acknowledgement: 92 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 93 * 94 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 95 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 96 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 97 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 98 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 99 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 100 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 101 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 102 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 103 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 104 * SUCH DAMAGE. 105 * 106 * The licence and distribution terms for any publically available version or 107 * derivative of this code cannot be changed. i.e. this code cannot simply be 108 * copied and put under another distribution licence 109 * [including the GNU Public Licence.] 110 */ 111 112 #include <stdio.h> 113 114 #include <openssl/opensslconf.h> 115 116 #include <openssl/err.h> 117 #include <openssl/rsa.h> 118 119 #include "bn_local.h" 120 #include "rsa_local.h" 121 122 #define BN_BLINDING_COUNTER 32 123 124 struct bn_blinding_st { 125 BIGNUM *A; 126 BIGNUM *Ai; 127 BIGNUM *e; 128 BIGNUM *mod; 129 CRYPTO_THREADID tid; 130 int counter; 131 BN_MONT_CTX *m_ctx; 132 int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, 133 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); 134 }; 135 136 BN_BLINDING * 137 BN_BLINDING_new(const BIGNUM *e, const BIGNUM *mod, BN_CTX *ctx, 138 int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, 139 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx), BN_MONT_CTX *m_ctx) 140 { 141 BN_BLINDING *ret = NULL; 142 143 if ((ret = calloc(1, sizeof(BN_BLINDING))) == NULL) { 144 BNerror(ERR_R_MALLOC_FAILURE); 145 goto err; 146 } 147 if ((ret->A = BN_new()) == NULL) 148 goto err; 149 if ((ret->Ai = BN_new()) == NULL) 150 goto err; 151 if ((ret->e = BN_dup(e)) == NULL) 152 goto err; 153 if ((ret->mod = BN_dup(mod)) == NULL) 154 goto err; 155 if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0) 156 BN_set_flags(ret->mod, BN_FLG_CONSTTIME); 157 158 /* Update on first use. */ 159 ret->counter = BN_BLINDING_COUNTER - 1; 160 CRYPTO_THREADID_current(&ret->tid); 161 162 if (bn_mod_exp != NULL) 163 ret->bn_mod_exp = bn_mod_exp; 164 if (m_ctx != NULL) 165 ret->m_ctx = m_ctx; 166 167 return ret; 168 169 err: 170 BN_BLINDING_free(ret); 171 172 return NULL; 173 } 174 175 void 176 BN_BLINDING_free(BN_BLINDING *r) 177 { 178 if (r == NULL) 179 return; 180 181 BN_free(r->A); 182 BN_free(r->Ai); 183 BN_free(r->e); 184 BN_free(r->mod); 185 free(r); 186 } 187 188 static int 189 BN_BLINDING_setup(BN_BLINDING *b, BN_CTX *ctx) 190 { 191 if (!bn_rand_interval(b->A, 1, b->mod)) 192 return 0; 193 if (BN_mod_inverse_ct(b->Ai, b->A, b->mod, ctx) == NULL) 194 return 0; 195 196 if (b->bn_mod_exp != NULL && b->m_ctx != NULL) { 197 if (!b->bn_mod_exp(b->A, b->A, b->e, b->mod, ctx, b->m_ctx)) 198 return 0; 199 } else { 200 if (!BN_mod_exp_ct(b->A, b->A, b->e, b->mod, ctx)) 201 return 0; 202 } 203 204 return 1; 205 } 206 207 static int 208 BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx) 209 { 210 int ret = 0; 211 212 if (++b->counter >= BN_BLINDING_COUNTER) { 213 if (!BN_BLINDING_setup(b, ctx)) 214 goto err; 215 b->counter = 0; 216 } else { 217 if (!BN_mod_sqr(b->A, b->A, b->mod, ctx)) 218 goto err; 219 if (!BN_mod_sqr(b->Ai, b->Ai, b->mod, ctx)) 220 goto err; 221 } 222 223 ret = 1; 224 225 err: 226 return ret; 227 } 228 229 int 230 BN_BLINDING_convert(BIGNUM *n, BIGNUM *inv, BN_BLINDING *b, BN_CTX *ctx) 231 { 232 int ret = 0; 233 234 if (!BN_BLINDING_update(b, ctx)) 235 goto err; 236 237 if (inv != NULL) { 238 if (!bn_copy(inv, b->Ai)) 239 goto err; 240 } 241 242 ret = BN_mod_mul(n, n, b->A, b->mod, ctx); 243 244 err: 245 return ret; 246 } 247 248 int 249 BN_BLINDING_invert(BIGNUM *n, const BIGNUM *inv, BN_BLINDING *b, BN_CTX *ctx) 250 { 251 if (inv == NULL) 252 inv = b->Ai; 253 254 return BN_mod_mul(n, n, inv, b->mod, ctx); 255 } 256 257 CRYPTO_THREADID * 258 BN_BLINDING_thread_id(BN_BLINDING *b) 259 { 260 return &b->tid; 261 } 262