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 pr0, d, p; 94 int bitsp, bitsq, ok = -1, n = 0; 95 BN_CTX *ctx = NULL; 96 97 ctx = BN_CTX_new(); 98 if (ctx == NULL) 99 goto err; 100 BN_CTX_start(ctx); 101 if ((r0 = BN_CTX_get(ctx)) == NULL) 102 goto err; 103 if ((r1 = BN_CTX_get(ctx)) == NULL) 104 goto err; 105 if ((r2 = BN_CTX_get(ctx)) == NULL) 106 goto err; 107 if ((r3 = BN_CTX_get(ctx)) == NULL) 108 goto err; 109 110 bitsp = (bits + 1) / 2; 111 bitsq = bits - bitsp; 112 113 /* We need the RSA components non-NULL */ 114 if (!rsa->n && ((rsa->n = BN_new()) == NULL)) 115 goto err; 116 if (!rsa->d && ((rsa->d = BN_new()) == NULL)) 117 goto err; 118 if (!rsa->e && ((rsa->e = BN_new()) == NULL)) 119 goto err; 120 if (!rsa->p && ((rsa->p = BN_new()) == NULL)) 121 goto err; 122 if (!rsa->q && ((rsa->q = BN_new()) == NULL)) 123 goto err; 124 if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL)) 125 goto err; 126 if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL)) 127 goto err; 128 if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL)) 129 goto err; 130 131 BN_copy(rsa->e, e_value); 132 133 /* generate p and q */ 134 for (;;) { 135 if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb)) 136 goto err; 137 if (!BN_sub(r2, rsa->p, BN_value_one())) 138 goto err; 139 if (!BN_gcd(r1, r2, rsa->e, ctx)) 140 goto err; 141 if (BN_is_one(r1)) 142 break; 143 if (!BN_GENCB_call(cb, 2, n++)) 144 goto err; 145 } 146 if (!BN_GENCB_call(cb, 3, 0)) 147 goto err; 148 for (;;) { 149 /* 150 * When generating ridiculously small keys, we can get stuck 151 * continually regenerating the same prime values. Check for 152 * this and bail if it happens 3 times. 153 */ 154 unsigned int degenerate = 0; 155 do { 156 if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, 157 cb)) 158 goto err; 159 } while (BN_cmp(rsa->p, rsa->q) == 0 && 160 ++degenerate < 3); 161 if (degenerate == 3) { 162 ok = 0; /* we set our own err */ 163 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, 164 RSA_R_KEY_SIZE_TOO_SMALL); 165 goto err; 166 } 167 if (!BN_sub(r2, rsa->q, BN_value_one())) 168 goto err; 169 if (!BN_gcd(r1, r2, rsa->e, ctx)) 170 goto err; 171 if (BN_is_one(r1)) 172 break; 173 if (!BN_GENCB_call(cb, 2, n++)) 174 goto err; 175 } 176 if (!BN_GENCB_call(cb, 3, 1)) 177 goto err; 178 if (BN_cmp(rsa->p, rsa->q) < 0) { 179 tmp = rsa->p; 180 rsa->p = rsa->q; 181 rsa->q = tmp; 182 } 183 184 /* calculate n */ 185 if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx)) 186 goto err; 187 188 /* calculate d */ 189 if (!BN_sub(r1, rsa->p, BN_value_one())) /* p-1 */ 190 goto err; 191 if (!BN_sub(r2, rsa->q, BN_value_one())) /* q-1 */ 192 goto err; 193 if (!BN_mul(r0, r1, r2, ctx)) /* (p-1)(q-1) */ 194 goto err; 195 196 BN_with_flags(&pr0, r0, BN_FLG_CONSTTIME); 197 198 if (!BN_mod_inverse(rsa->d, rsa->e, &pr0, ctx)) /* d */ 199 goto err; 200 201 /* set up d for correct BN_FLG_CONSTTIME flag */ 202 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME); 203 204 /* calculate d mod (p-1) */ 205 if (!BN_mod(rsa->dmp1, &d, r1, ctx)) 206 goto err; 207 208 /* calculate d mod (q-1) */ 209 if (!BN_mod(rsa->dmq1, &d, r2, ctx)) 210 goto err; 211 212 /* calculate inverse of q mod p */ 213 BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME); 214 if (!BN_mod_inverse(rsa->iqmp, rsa->q, &p, ctx)) 215 goto err; 216 217 ok = 1; 218 err: 219 if (ok == -1) { 220 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN); 221 ok = 0; 222 } 223 if (ctx != NULL) { 224 BN_CTX_end(ctx); 225 BN_CTX_free(ctx); 226 } 227 228 return ok; 229 } 230