1 /* $OpenBSD: rsa_gen.c,v 1.17 2015/02/09 15:49:22 jsing Exp $ */ 2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay@cryptsoft.com). 7 * The implementation was written so as to conform with Netscapes SSL. 8 * 9 * This library is free for commercial and non-commercial use as long as 10 * the following conditions are aheared to. The following conditions 11 * apply to all code found in this distribution, be it the RC4, RSA, 12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 13 * included with this distribution is covered by the same copyright terms 14 * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15 * 16 * Copyright remains Eric Young's, and as such any Copyright notices in 17 * the code are not to be removed. 18 * If this package is used in a product, Eric Young should be given attribution 19 * as the author of the parts of the library used. 20 * This can be in the form of a textual message at program startup or 21 * in documentation (online or textual) provided with the package. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 26 * 1. Redistributions of source code must retain the copyright 27 * notice, this list of conditions and the following disclaimer. 28 * 2. Redistributions in binary form must reproduce the above copyright 29 * notice, this list of conditions and the following disclaimer in the 30 * documentation and/or other materials provided with the distribution. 31 * 3. All advertising materials mentioning features or use of this software 32 * must display the following acknowledgement: 33 * "This product includes cryptographic software written by 34 * Eric Young (eay@cryptsoft.com)" 35 * The word 'cryptographic' can be left out if the rouines from the library 36 * being used are not cryptographic related :-). 37 * 4. If you include any Windows specific code (or a derivative thereof) from 38 * the apps directory (application code) you must include an acknowledgement: 39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40 * 41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51 * SUCH DAMAGE. 52 * 53 * The licence and distribution terms for any publically available version or 54 * derivative of this code cannot be changed. i.e. this code cannot simply be 55 * copied and put under another distribution licence 56 * [including the GNU Public Licence.] 57 */ 58 59 60 /* NB: these functions have been "upgraded", the deprecated versions (which are 61 * compatibility wrappers using these functions) are in rsa_depr.c. 62 * - Geoff 63 */ 64 65 #include <stdio.h> 66 #include <time.h> 67 68 #include <openssl/bn.h> 69 #include <openssl/err.h> 70 #include <openssl/rsa.h> 71 72 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb); 73 74 /* 75 * NB: this wrapper would normally be placed in rsa_lib.c and the static 76 * implementation would probably be in rsa_eay.c. Nonetheless, is kept here so 77 * that we don't introduce a new linker dependency. Eg. any application that 78 * wasn't previously linking object code related to key-generation won't have to 79 * now just because key-generation is part of RSA_METHOD. 80 */ 81 int 82 RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) 83 { 84 if (rsa->meth->rsa_keygen) 85 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); 86 return rsa_builtin_keygen(rsa, bits, e_value, cb); 87 } 88 89 static int 90 rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) 91 { 92 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp; 93 BIGNUM local_r0, local_d, local_p; 94 BIGNUM *pr0, *d, *p; 95 int bitsp, bitsq, ok = -1, n = 0; 96 BN_CTX *ctx = NULL; 97 98 ctx = BN_CTX_new(); 99 if (ctx == NULL) 100 goto err; 101 BN_CTX_start(ctx); 102 if ((r0 = BN_CTX_get(ctx)) == NULL) 103 goto err; 104 if ((r1 = BN_CTX_get(ctx)) == NULL) 105 goto err; 106 if ((r2 = BN_CTX_get(ctx)) == NULL) 107 goto err; 108 if ((r3 = BN_CTX_get(ctx)) == NULL) 109 goto err; 110 111 bitsp = (bits + 1) / 2; 112 bitsq = bits - bitsp; 113 114 /* We need the RSA components non-NULL */ 115 if (!rsa->n && ((rsa->n = BN_new()) == NULL)) 116 goto err; 117 if (!rsa->d && ((rsa->d = BN_new()) == NULL)) 118 goto err; 119 if (!rsa->e && ((rsa->e = BN_new()) == NULL)) 120 goto err; 121 if (!rsa->p && ((rsa->p = BN_new()) == NULL)) 122 goto err; 123 if (!rsa->q && ((rsa->q = BN_new()) == NULL)) 124 goto err; 125 if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL)) 126 goto err; 127 if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL)) 128 goto err; 129 if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL)) 130 goto err; 131 132 BN_copy(rsa->e, e_value); 133 134 /* generate p and q */ 135 for (;;) { 136 if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb)) 137 goto err; 138 if (!BN_sub(r2, rsa->p, BN_value_one())) 139 goto err; 140 if (!BN_gcd(r1, r2, rsa->e, ctx)) 141 goto err; 142 if (BN_is_one(r1)) 143 break; 144 if (!BN_GENCB_call(cb, 2, n++)) 145 goto err; 146 } 147 if (!BN_GENCB_call(cb, 3, 0)) 148 goto err; 149 for (;;) { 150 /* 151 * When generating ridiculously small keys, we can get stuck 152 * continually regenerating the same prime values. Check for 153 * this and bail if it happens 3 times. 154 */ 155 unsigned int degenerate = 0; 156 do { 157 if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, 158 cb)) 159 goto err; 160 } while (BN_cmp(rsa->p, rsa->q) == 0 && 161 ++degenerate < 3); 162 if (degenerate == 3) { 163 ok = 0; /* we set our own err */ 164 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, 165 RSA_R_KEY_SIZE_TOO_SMALL); 166 goto err; 167 } 168 if (!BN_sub(r2, rsa->q, BN_value_one())) 169 goto err; 170 if (!BN_gcd(r1, r2, rsa->e, ctx)) 171 goto err; 172 if (BN_is_one(r1)) 173 break; 174 if (!BN_GENCB_call(cb, 2, n++)) 175 goto err; 176 } 177 if (!BN_GENCB_call(cb, 3, 1)) 178 goto err; 179 if (BN_cmp(rsa->p, rsa->q) < 0) { 180 tmp = rsa->p; 181 rsa->p = rsa->q; 182 rsa->q = tmp; 183 } 184 185 /* calculate n */ 186 if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx)) 187 goto err; 188 189 /* calculate d */ 190 if (!BN_sub(r1, rsa->p, BN_value_one())) /* p-1 */ 191 goto err; 192 if (!BN_sub(r2, rsa->q, BN_value_one())) /* q-1 */ 193 goto err; 194 if (!BN_mul(r0, r1, r2, ctx)) /* (p-1)(q-1) */ 195 goto err; 196 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) { 197 pr0 = &local_r0; 198 BN_with_flags(pr0, r0, BN_FLG_CONSTTIME); 199 } else 200 pr0 = r0; 201 if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) /* d */ 202 goto err; 203 204 /* set up d for correct BN_FLG_CONSTTIME flag */ 205 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) { 206 d = &local_d; 207 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME); 208 } else 209 d = rsa->d; 210 211 /* calculate d mod (p-1) */ 212 if (!BN_mod(rsa->dmp1, d, r1, ctx)) 213 goto err; 214 215 /* calculate d mod (q-1) */ 216 if (!BN_mod(rsa->dmq1, d, r2, ctx)) 217 goto err; 218 219 /* calculate inverse of q mod p */ 220 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) { 221 p = &local_p; 222 BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME); 223 } else 224 p = rsa->p; 225 if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) 226 goto err; 227 228 ok = 1; 229 err: 230 if (ok == -1) { 231 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN); 232 ok = 0; 233 } 234 if (ctx != NULL) { 235 BN_CTX_end(ctx); 236 BN_CTX_free(ctx); 237 } 238 239 return ok; 240 } 241