1/* $OpenBSD: rsa_gen.c,v 1.30 2023/07/08 12:26:45 beck 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 69static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb); 70 71int 72RSA_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} 78LCRYPTO_ALIAS(RSA_generate_key_ex); 79 80static int 81rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) 82{ 83 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp; 84 BIGNUM pr0, d, p; 85 int bitsp, bitsq, ok = -1, n = 0; 86 BN_CTX *ctx = NULL; 87 88 ctx = BN_CTX_new(); 89 if (ctx == NULL) 90 goto err; 91 BN_CTX_start(ctx); 92 if ((r0 = BN_CTX_get(ctx)) == NULL) 93 goto err; 94 if ((r1 = BN_CTX_get(ctx)) == NULL) 95 goto err; 96 if ((r2 = BN_CTX_get(ctx)) == NULL) 97 goto err; 98 if ((r3 = BN_CTX_get(ctx)) == NULL) 99 goto err; 100 101 bitsp = (bits + 1) / 2; 102 bitsq = bits - bitsp; 103 104 /* We need the RSA components non-NULL */ 105 if (!rsa->n && ((rsa->n = BN_new()) == NULL)) 106 goto err; 107 if (!rsa->d && ((rsa->d = BN_new()) == NULL)) 108 goto err; 109 if (!rsa->e && ((rsa->e = BN_new()) == NULL)) 110 goto err; 111 if (!rsa->p && ((rsa->p = BN_new()) == NULL)) 112 goto err; 113 if (!rsa->q && ((rsa->q = BN_new()) == NULL)) 114 goto err; 115 if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL)) 116 goto err; 117 if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL)) 118 goto err; 119 if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL)) 120 goto err; 121 122 if (!bn_copy(rsa->e, e_value)) 123 goto err; 124 125 /* generate p and q */ 126 for (;;) { 127 if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb)) 128 goto err; 129 if (!BN_sub(r2, rsa->p, BN_value_one())) 130 goto err; 131 if (!BN_gcd_ct(r1, r2, rsa->e, ctx)) 132 goto err; 133 if (BN_is_one(r1)) 134 break; 135 if (!BN_GENCB_call(cb, 2, n++)) 136 goto err; 137 } 138 if (!BN_GENCB_call(cb, 3, 0)) 139 goto err; 140 for (;;) { 141 /* 142 * When generating ridiculously small keys, we can get stuck 143 * continually regenerating the same prime values. Check for 144 * this and bail if it happens 3 times. 145 */ 146 unsigned int degenerate = 0; 147 do { 148 if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, 149 cb)) 150 goto err; 151 } while (BN_cmp(rsa->p, rsa->q) == 0 && 152 ++degenerate < 3); 153 if (degenerate == 3) { 154 ok = 0; /* we set our own err */ 155 RSAerror(RSA_R_KEY_SIZE_TOO_SMALL); 156 goto err; 157 } 158 if (!BN_sub(r2, rsa->q, BN_value_one())) 159 goto err; 160 if (!BN_gcd_ct(r1, r2, rsa->e, ctx)) 161 goto err; 162 if (BN_is_one(r1)) 163 break; 164 if (!BN_GENCB_call(cb, 2, n++)) 165 goto err; 166 } 167 if (!BN_GENCB_call(cb, 3, 1)) 168 goto err; 169 if (BN_cmp(rsa->p, rsa->q) < 0) { 170 tmp = rsa->p; 171 rsa->p = rsa->q; 172 rsa->q = tmp; 173 } 174 175 /* calculate n */ 176 if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx)) 177 goto err; 178 179 /* calculate d */ 180 if (!BN_sub(r1, rsa->p, BN_value_one())) /* p-1 */ 181 goto err; 182 if (!BN_sub(r2, rsa->q, BN_value_one())) /* q-1 */ 183 goto err; 184 if (!BN_mul(r0, r1, r2, ctx)) /* (p-1)(q-1) */ 185 goto err; 186 187 BN_init(&pr0); 188 BN_with_flags(&pr0, r0, BN_FLG_CONSTTIME); 189 190 if (BN_mod_inverse_ct(rsa->d, rsa->e, &pr0, ctx) == NULL) /* d */ 191 goto err; 192 193 /* set up d for correct BN_FLG_CONSTTIME flag */ 194 BN_init(&d); 195 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME); 196 197 /* calculate d mod (p-1) */ 198 if (!BN_mod_ct(rsa->dmp1, &d, r1, ctx)) 199 goto err; 200 201 /* calculate d mod (q-1) */ 202 if (!BN_mod_ct(rsa->dmq1, &d, r2, ctx)) 203 goto err; 204 205 /* calculate inverse of q mod p */ 206 BN_init(&p); 207 BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME); 208 if (BN_mod_inverse_ct(rsa->iqmp, rsa->q, &p, ctx) == NULL) 209 goto err; 210 211 ok = 1; 212err: 213 if (ok == -1) { 214 RSAerror(ERR_LIB_BN); 215 ok = 0; 216 } 217 if (ctx != NULL) { 218 BN_CTX_end(ctx); 219 BN_CTX_free(ctx); 220 } 221 222 return ok; 223} 224 225RSA * 226RSA_generate_key(int bits, unsigned long e_value, 227 void (*callback)(int, int, void *), void *cb_arg) 228{ 229 BN_GENCB cb; 230 int i; 231 RSA *rsa = RSA_new(); 232 BIGNUM *e = BN_new(); 233 234 if (!rsa || !e) 235 goto err; 236 237 /* The problem is when building with 8, 16, or 32 BN_ULONG, 238 * unsigned long can be larger */ 239 for (i = 0; i < (int)sizeof(unsigned long) * 8; i++) { 240 if (e_value & (1UL << i)) 241 if (BN_set_bit(e, i) == 0) 242 goto err; 243 } 244 245 BN_GENCB_set_old(&cb, callback, cb_arg); 246 247 if (RSA_generate_key_ex(rsa, bits, e, &cb)) { 248 BN_free(e); 249 return rsa; 250 } 251err: 252 BN_free(e); 253 RSA_free(rsa); 254 255 return 0; 256} 257LCRYPTO_ALIAS(RSA_generate_key); 258