1 /* $OpenBSD: rsa_gen.c,v 1.29 2023/04/13 15:18:29 tb 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 #include <stdio.h> 60 #include <time.h> 61 62 #include <openssl/bn.h> 63 #include <openssl/err.h> 64 #include <openssl/rsa.h> 65 66 #include "bn_local.h" 67 #include "rsa_local.h" 68 69 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb); 70 71 int 72 RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) 73 { 74 if (rsa->meth->rsa_keygen) 75 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); 76 return rsa_builtin_keygen(rsa, bits, e_value, cb); 77 } 78 79 static int 80 rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) 81 { 82 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp; 83 BIGNUM pr0, d, p; 84 int bitsp, bitsq, ok = -1, n = 0; 85 BN_CTX *ctx = NULL; 86 87 ctx = BN_CTX_new(); 88 if (ctx == NULL) 89 goto err; 90 BN_CTX_start(ctx); 91 if ((r0 = BN_CTX_get(ctx)) == NULL) 92 goto err; 93 if ((r1 = BN_CTX_get(ctx)) == NULL) 94 goto err; 95 if ((r2 = BN_CTX_get(ctx)) == NULL) 96 goto err; 97 if ((r3 = BN_CTX_get(ctx)) == NULL) 98 goto err; 99 100 bitsp = (bits + 1) / 2; 101 bitsq = bits - bitsp; 102 103 /* We need the RSA components non-NULL */ 104 if (!rsa->n && ((rsa->n = BN_new()) == NULL)) 105 goto err; 106 if (!rsa->d && ((rsa->d = BN_new()) == NULL)) 107 goto err; 108 if (!rsa->e && ((rsa->e = BN_new()) == NULL)) 109 goto err; 110 if (!rsa->p && ((rsa->p = BN_new()) == NULL)) 111 goto err; 112 if (!rsa->q && ((rsa->q = BN_new()) == NULL)) 113 goto err; 114 if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL)) 115 goto err; 116 if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL)) 117 goto err; 118 if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL)) 119 goto err; 120 121 if (!bn_copy(rsa->e, e_value)) 122 goto err; 123 124 /* generate p and q */ 125 for (;;) { 126 if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb)) 127 goto err; 128 if (!BN_sub(r2, rsa->p, BN_value_one())) 129 goto err; 130 if (!BN_gcd_ct(r1, r2, rsa->e, ctx)) 131 goto err; 132 if (BN_is_one(r1)) 133 break; 134 if (!BN_GENCB_call(cb, 2, n++)) 135 goto err; 136 } 137 if (!BN_GENCB_call(cb, 3, 0)) 138 goto err; 139 for (;;) { 140 /* 141 * When generating ridiculously small keys, we can get stuck 142 * continually regenerating the same prime values. Check for 143 * this and bail if it happens 3 times. 144 */ 145 unsigned int degenerate = 0; 146 do { 147 if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, 148 cb)) 149 goto err; 150 } while (BN_cmp(rsa->p, rsa->q) == 0 && 151 ++degenerate < 3); 152 if (degenerate == 3) { 153 ok = 0; /* we set our own err */ 154 RSAerror(RSA_R_KEY_SIZE_TOO_SMALL); 155 goto err; 156 } 157 if (!BN_sub(r2, rsa->q, BN_value_one())) 158 goto err; 159 if (!BN_gcd_ct(r1, r2, rsa->e, ctx)) 160 goto err; 161 if (BN_is_one(r1)) 162 break; 163 if (!BN_GENCB_call(cb, 2, n++)) 164 goto err; 165 } 166 if (!BN_GENCB_call(cb, 3, 1)) 167 goto err; 168 if (BN_cmp(rsa->p, rsa->q) < 0) { 169 tmp = rsa->p; 170 rsa->p = rsa->q; 171 rsa->q = tmp; 172 } 173 174 /* calculate n */ 175 if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx)) 176 goto err; 177 178 /* calculate d */ 179 if (!BN_sub(r1, rsa->p, BN_value_one())) /* p-1 */ 180 goto err; 181 if (!BN_sub(r2, rsa->q, BN_value_one())) /* q-1 */ 182 goto err; 183 if (!BN_mul(r0, r1, r2, ctx)) /* (p-1)(q-1) */ 184 goto err; 185 186 BN_init(&pr0); 187 BN_with_flags(&pr0, r0, BN_FLG_CONSTTIME); 188 189 if (BN_mod_inverse_ct(rsa->d, rsa->e, &pr0, ctx) == NULL) /* d */ 190 goto err; 191 192 /* set up d for correct BN_FLG_CONSTTIME flag */ 193 BN_init(&d); 194 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME); 195 196 /* calculate d mod (p-1) */ 197 if (!BN_mod_ct(rsa->dmp1, &d, r1, ctx)) 198 goto err; 199 200 /* calculate d mod (q-1) */ 201 if (!BN_mod_ct(rsa->dmq1, &d, r2, ctx)) 202 goto err; 203 204 /* calculate inverse of q mod p */ 205 BN_init(&p); 206 BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME); 207 if (BN_mod_inverse_ct(rsa->iqmp, rsa->q, &p, ctx) == NULL) 208 goto err; 209 210 ok = 1; 211 err: 212 if (ok == -1) { 213 RSAerror(ERR_LIB_BN); 214 ok = 0; 215 } 216 if (ctx != NULL) { 217 BN_CTX_end(ctx); 218 BN_CTX_free(ctx); 219 } 220 221 return ok; 222 } 223 224 RSA * 225 RSA_generate_key(int bits, unsigned long e_value, 226 void (*callback)(int, int, void *), void *cb_arg) 227 { 228 BN_GENCB cb; 229 int i; 230 RSA *rsa = RSA_new(); 231 BIGNUM *e = BN_new(); 232 233 if (!rsa || !e) 234 goto err; 235 236 /* The problem is when building with 8, 16, or 32 BN_ULONG, 237 * unsigned long can be larger */ 238 for (i = 0; i < (int)sizeof(unsigned long) * 8; i++) { 239 if (e_value & (1UL << i)) 240 if (BN_set_bit(e, i) == 0) 241 goto err; 242 } 243 244 BN_GENCB_set_old(&cb, callback, cb_arg); 245 246 if (RSA_generate_key_ex(rsa, bits, e, &cb)) { 247 BN_free(e); 248 return rsa; 249 } 250 err: 251 BN_free(e); 252 RSA_free(rsa); 253 254 return 0; 255 } 256