crypto/rsa/rsa_sp800_56b_gen.c

   1 /*
   2  * Copyright 2018-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright (c) 2018-2019, Oracle and/or its affiliates.  All rights reserved.
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 #include <openssl/err.h>
  12 #include <openssl/bn.h>
  13 #include "crypto/bn.h"
  14 #include "crypto/security_bits.h"
  15 #include "rsa_local.h"
  16
  17 #define RSA_FIPS1864_MIN_KEYGEN_KEYSIZE 2048
  18 #define RSA_FIPS1864_MIN_KEYGEN_STRENGTH 112
  19 #define RSA_FIPS1864_MAX_KEYGEN_STRENGTH 256
  20
  21 /*
  22  * Generate probable primes 'p' & 'q'. See FIPS 186-4 Section B.3.6
  23  * "Generation of Probable Primes with Conditions Based on Auxiliary Probable
  24  * Primes".
  25  *
  26  * Params:
  27  *     rsa  Object used to store primes p & q.
  28  *     p1, p2 The returned auxiliary primes for p. If NULL they are not returned.
  29  *     Xpout An optionally returned random number used during generation of p.
  30  *     Xp An optional passed in value (that is random number used during
  31  *        generation of p).
  32  *     Xp1, Xp2 Optionally passed in randomly generated numbers from which
  33  *              auxiliary primes p1 & p2 are calculated. If NULL these values
  34  *              are generated internally.
  35  *     q1, q2 The returned auxiliary primes for q. If NULL they are not returned.
  36  *     Xqout An optionally returned random number used during generation of q.
  37  *     Xq An optional passed in value (that is random number used during
  38  *        generation of q).
  39  *     Xq1, Xq2 Optionally passed in randomly generated numbers from which
  40  *              auxiliary primes q1 & q2 are calculated. If NULL these values
  41  *              are generated internally.
  42  *     nbits The key size in bits (The size of the modulus n).
  43  *     e The public exponent.
  44  *     ctx A BN_CTX object.
  45  *     cb An optional BIGNUM callback.
  46  * Returns: 1 if successful, or  0 otherwise.
  47  * Notes:
  48  *     p1, p2, q1, q2, Xpout, Xqout are returned if they are not NULL.
  49  *     Xp, Xp1, Xp2, Xq, Xq1, Xq2 are optionally passed in.
  50  *     (Required for CAVS testing).
  51  */
  52 int rsa_fips186_4_gen_prob_primes(RSA *rsa, BIGNUM *p1, BIGNUM *p2,
  53                                   BIGNUM *Xpout, const BIGNUM *Xp,
  54                                   const BIGNUM *Xp1, const BIGNUM *Xp2,
  55                                   BIGNUM *q1, BIGNUM *q2, BIGNUM *Xqout,
  56                                   const BIGNUM *Xq, const BIGNUM *Xq1,
  57                                   const BIGNUM *Xq2, int nbits,
  58                                   const BIGNUM *e, BN_CTX *ctx, BN_GENCB *cb)
  59 {
  60     int ret = 0, ok;
  61     BIGNUM *Xpo = NULL, *Xqo = NULL, *tmp = NULL;
  62
  63     /* (Step 1) Check key length
  64      * NOTE: SP800-131A Rev1 Disallows key lengths of < 2048 bits for RSA
  65      * Signature Generation and Key Agree/Transport.
  66      */
  67     if (nbits < RSA_FIPS1864_MIN_KEYGEN_KEYSIZE) {
  68         RSAerr(RSA_F_RSA_FIPS186_4_GEN_PROB_PRIMES, RSA_R_INVALID_KEY_LENGTH);
  69         return 0;
  70     }
  71
  72     if (!rsa_check_public_exponent(e)) {
  73         RSAerr(RSA_F_RSA_FIPS186_4_GEN_PROB_PRIMES,
  74                RSA_R_PUB_EXPONENT_OUT_OF_RANGE);
  75         return 0;
  76     }
  77
  78     /* (Step 3) Determine strength and check rand generator strength is ok -
  79      * this step is redundant because the generator always returns a higher
  80      * strength than is required.
  81      */
  82
  83     BN_CTX_start(ctx);
  84     tmp = BN_CTX_get(ctx);
  85     Xpo = (Xpout != NULL) ? Xpout : BN_CTX_get(ctx);
  86     Xqo = (Xqout != NULL) ? Xqout : BN_CTX_get(ctx);
  87     if (tmp == NULL || Xpo == NULL || Xqo == NULL)
  88         goto err;
  89
  90     if (rsa->p == NULL)
  91         rsa->p = BN_secure_new();
  92     if (rsa->q == NULL)
  93         rsa->q = BN_secure_new();
  94     if (rsa->p == NULL || rsa->q == NULL)
  95         goto err;
  96
  97     /* (Step 4) Generate p, Xp */
  98     if (!bn_rsa_fips186_4_gen_prob_primes(rsa->p, Xpo, p1, p2, Xp, Xp1, Xp2,
  99                                           nbits, e, ctx, cb))
 100         goto err;
 101     for(;;) {
 102         /* (Step 5) Generate q, Xq*/
 103         if (!bn_rsa_fips186_4_gen_prob_primes(rsa->q, Xqo, q1, q2, Xq, Xq1,
 104                                               Xq2, nbits, e, ctx, cb))
 105             goto err;
 106
 107         /* (Step 6) |Xp - Xq| > 2^(nbitlen/2 - 100) */
 108         ok = rsa_check_pminusq_diff(tmp, Xpo, Xqo, nbits);
 109         if (ok < 0)
 110             goto err;
 111         if (ok == 0)
 112             continue;
 113
 114         /* (Step 6) |p - q| > 2^(nbitlen/2 - 100) */
 115         ok = rsa_check_pminusq_diff(tmp, rsa->p, rsa->q, nbits);
 116         if (ok < 0)
 117             goto err;
 118         if (ok == 0)
 119             continue;
 120         break; /* successfully finished */
 121     }
 122     rsa->dirty_cnt++;
 123     ret = 1;
 124 err:
 125     /* Zeroize any internally generated values that are not returned */
 126     if (Xpo != Xpout)
 127         BN_clear(Xpo);
 128     if (Xqo != Xqout)
 129         BN_clear(Xqo);
 130     BN_clear(tmp);
 131
 132     BN_CTX_end(ctx);
 133     return ret;
 134 }
 135
 136 /*
 137  * Validates the RSA key size based on the target strength.
 138  * See SP800-56Br1 6.3.1.1 (Steps 1a-1b)
 139  *
 140  * Params:
 141  *     nbits The key size in bits.
 142  *     strength The target strength in bits. -1 means the target
 143  *              strength is unknown.
 144  * Returns: 1 if the key size matches the target strength, or 0 otherwise.
 145  */
 146 int rsa_sp800_56b_validate_strength(int nbits, int strength)
 147 {
 148     int s = (int)ifc_ffc_compute_security_bits(nbits);
 149
 150     if (s < RSA_FIPS1864_MIN_KEYGEN_STRENGTH
 151             || s > RSA_FIPS1864_MAX_KEYGEN_STRENGTH) {
 152         RSAerr(RSA_F_RSA_SP800_56B_VALIDATE_STRENGTH, RSA_R_INVALID_MODULUS);
 153         return 0;
 154     }
 155     if (strength != -1 && s != strength) {
 156         RSAerr(RSA_F_RSA_SP800_56B_VALIDATE_STRENGTH, RSA_R_INVALID_STRENGTH);
 157         return 0;
 158     }
 159     return 1;
 160 }
 161
 162 /*
 163  *
 164  * Using p & q, calculate other required parameters such as n, d.
 165  * as well as the CRT parameters dP, dQ, qInv.
 166  *
 167  * See SP800-56Br1
 168  *   6.3.1.1 rsakpg1 - basic (Steps 3-4)
 169  *   6.3.1.3 rsakpg1 - crt   (Step 5)
 170  *
 171  * Params:
 172  *     rsa An rsa object.
 173  *     nbits The key size.
 174  *     e The public exponent.
 175  *     ctx A BN_CTX object.
 176  * Notes:
 177  *   There is a small chance that the generated d will be too small.
 178  * Returns: -1 = error,
 179  *           0 = d is too small,
 180  *           1 = success.
 181  */
 182 int rsa_sp800_56b_derive_params_from_pq(RSA *rsa, int nbits,
 183                                         const BIGNUM *e, BN_CTX *ctx)
 184 {
 185     int ret = -1;
 186     BIGNUM *p1, *q1, *lcm, *p1q1, *gcd;
 187
 188     BN_CTX_start(ctx);
 189     p1 = BN_CTX_get(ctx);
 190     q1 = BN_CTX_get(ctx);
 191     lcm = BN_CTX_get(ctx);
 192     p1q1 = BN_CTX_get(ctx);
 193     gcd = BN_CTX_get(ctx);
 194     if (gcd == NULL)
 195         goto err;
 196
 197     /* LCM((p-1, q-1)) */
 198     if (rsa_get_lcm(ctx, rsa->p, rsa->q, lcm, gcd, p1, q1, p1q1) != 1)
 199         goto err;
 200
 201     /* copy e */
 202     BN_free(rsa->e);
 203     rsa->e = BN_dup(e);
 204     if (rsa->e == NULL)
 205         goto err;
 206
 207     BN_clear_free(rsa->d);
 208     /* (Step 3) d = (e^-1) mod (LCM(p-1, q-1)) */
 209     rsa->d = BN_secure_new();
 210     if (rsa->d == NULL || BN_mod_inverse(rsa->d, e, lcm, ctx) == NULL)
 211         goto err;
 212
 213     /* (Step 3) return an error if d is too small */
 214     if (BN_num_bits(rsa->d) <= (nbits >> 1)) {
 215         ret = 0;
 216         goto err;
 217     }
 218
 219     /* (Step 4) n = pq */
 220     if (rsa->n == NULL)
 221         rsa->n = BN_new();
 222     if (rsa->n == NULL || !BN_mul(rsa->n, rsa->p, rsa->q, ctx))
 223         goto err;
 224
 225     /* (Step 5a) dP = d mod (p-1) */
 226     if (rsa->dmp1 == NULL)
 227         rsa->dmp1 = BN_new();
 228     if (rsa->dmp1 == NULL || !BN_mod(rsa->dmp1, rsa->d, p1, ctx))
 229         goto err;
 230
 231     /* (Step 5b) dQ = d mod (q-1) */
 232     if (rsa->dmq1 == NULL)
 233         rsa->dmq1 = BN_secure_new();
 234     if (rsa->dmq1 == NULL || !BN_mod(rsa->dmq1, rsa->d, q1, ctx))
 235         goto err;
 236
 237     /* (Step 5c) qInv = (inverse of q) mod p */
 238     BN_free(rsa->iqmp);
 239     rsa->iqmp = BN_secure_new();
 240     if (rsa->iqmp == NULL
 241             || BN_mod_inverse(rsa->iqmp, rsa->q, rsa->p, ctx) == NULL)
 242         goto err;
 243
 244     rsa->dirty_cnt++;
 245     ret = 1;
 246 err:
 247     if (ret != 1) {
 248         BN_free(rsa->e);
 249         rsa->e = NULL;
 250         BN_free(rsa->d);
 251         rsa->d = NULL;
 252         BN_free(rsa->n);
 253         rsa->n = NULL;
 254         BN_free(rsa->iqmp);
 255         rsa->iqmp = NULL;
 256         BN_free(rsa->dmq1);
 257         rsa->dmq1 = NULL;
 258         BN_free(rsa->dmp1);
 259         rsa->dmp1 = NULL;
 260     }
 261     BN_clear(p1);
 262     BN_clear(q1);
 263     BN_clear(lcm);
 264     BN_clear(p1q1);
 265     BN_clear(gcd);
 266
 267     BN_CTX_end(ctx);
 268     return ret;
 269 }
 270
 271 /*
 272  * Generate a SP800-56B RSA key.
 273  *
 274  * See SP800-56Br1 6.3.1 "RSA Key-Pair Generation with a Fixed Public Exponent"
 275  *    6.3.1.1 rsakpg1 - basic
 276  *    6.3.1.3 rsakpg1 - crt
 277  *
 278  * See also FIPS 186-4 Section B.3.6
 279  * "Generation of Probable Primes with Conditions Based on Auxiliary
 280  * Probable Primes."
 281  *
 282  * Params:
 283  *     rsa The rsa object.
 284  *     nbits The intended key size in bits.
 285  *     efixed The public exponent. If NULL a default of 65537 is used.
 286  *     cb An optional BIGNUM callback.
 287  * Returns: 1 if successfully generated otherwise it returns 0.
 288  */
 289 int rsa_sp800_56b_generate_key(RSA *rsa, int nbits, const BIGNUM *efixed,
 290                                BN_GENCB *cb)
 291 {
 292     int ret = 0;
 293     int ok;
 294     BN_CTX *ctx = NULL;
 295     BIGNUM *e = NULL;
 296
 297     /* (Steps 1a-1b) : Currently ignores the strength check */
 298     if (!rsa_sp800_56b_validate_strength(nbits, -1))
 299         return 0;
 300
 301     ctx = BN_CTX_new_ex(rsa->libctx);
 302     if (ctx == NULL)
 303         return 0;
 304
 305     /* Set default if e is not passed in */
 306     if (efixed == NULL) {
 307         e = BN_new();
 308         if (e == NULL || !BN_set_word(e, 65537))
 309             goto err;
 310     } else {
 311         e = (BIGNUM *)efixed;
 312     }
 313     /* (Step 1c) fixed exponent is checked later . */
 314
 315     for (;;) {
 316         /* (Step 2) Generate prime factors */
 317         if (!rsa_fips186_4_gen_prob_primes(rsa, NULL, NULL, NULL, NULL, NULL,
 318                                            NULL, NULL, NULL, NULL, NULL, NULL,
 319                                            NULL, nbits, e, ctx, cb))
 320             goto err;
 321         /* (Steps 3-5) Compute params d, n, dP, dQ, qInv */
 322         ok = rsa_sp800_56b_derive_params_from_pq(rsa, nbits, e, ctx);
 323         if (ok < 0)
 324             goto err;
 325         if (ok > 0)
 326             break;
 327         /* Gets here if computed d is too small - so try again */
 328     }
 329
 330     /* (Step 6) Do pairwise test - optional validity test has been omitted */
 331     ret = rsa_sp800_56b_pairwise_test(rsa, ctx);
 332 err:
 333     if (efixed == NULL)
 334         BN_free(e);
 335     BN_CTX_free(ctx);
 336     return ret;
 337 }
 338
 339 /*
 340  * See SP800-56Br1 6.3.1.3 (Step 6) Perform a pair-wise consistency test by
 341  * verifying that: k = (k^e)^d mod n for some integer k where 1 < k < n-1.
 342  *
 343  * Returns 1 if the RSA key passes the pairwise test or 0 it it fails.
 344  */
 345 int rsa_sp800_56b_pairwise_test(RSA *rsa, BN_CTX *ctx)
 346 {
 347     int ret = 0;
 348     BIGNUM *k, *tmp;
 349
 350     BN_CTX_start(ctx);
 351     tmp = BN_CTX_get(ctx);
 352     k = BN_CTX_get(ctx);
 353     if (k == NULL)
 354         goto err;
 355
 356     ret = (BN_set_word(k, 2)
 357           && BN_mod_exp(tmp, k, rsa->e, rsa->n, ctx)
 358           && BN_mod_exp(tmp, tmp, rsa->d, rsa->n, ctx)
 359           && BN_cmp(k, tmp) == 0);
 360     if (ret == 0)
 361         RSAerr(RSA_F_RSA_SP800_56B_PAIRWISE_TEST, RSA_R_PAIRWISE_TEST_FAILURE);
 362 err:
 363     BN_CTX_end(ctx);
 364     return ret;
 365 }