crypto/dsa/dsa_key.c

   1 /*
   2  * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 /*
  11  * DSA low level APIs are deprecated for public use, but still ok for
  12  * internal use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include <stdio.h>
  17 #include <time.h>
  18 #include "internal/cryptlib.h"
  19 #include <openssl/bn.h>
  20 #include <openssl/self_test.h>
  21 #include "crypto/dsa.h"
  22 #include "dsa_local.h"
  23
  24 #ifdef FIPS_MODULE
  25 # define MIN_STRENGTH 112
  26 #else
  27 # define MIN_STRENGTH 80
  28 #endif
  29
  30 static int dsa_keygen(DSA *dsa, int pairwise_test);
  31 static int dsa_keygen_pairwise_test(DSA *dsa, OSSL_CALLBACK *cb, void *cbarg);
  32
  33 int DSA_generate_key(DSA *dsa)
  34 {
  35 #ifndef FIPS_MODULE
  36     if (dsa->meth->dsa_keygen != NULL)
  37         return dsa->meth->dsa_keygen(dsa);
  38 #endif
  39     return dsa_keygen(dsa, 0);
  40 }
  41
  42 int dsa_generate_public_key(BN_CTX *ctx, const DSA *dsa, const BIGNUM *priv_key,
  43                             BIGNUM *pub_key)
  44 {
  45     int ret = 0;
  46     BIGNUM *prk = BN_new();
  47
  48     if (prk == NULL)
  49         return 0;
  50     BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
  51
  52     /* pub_key = g ^ priv_key mod p */
  53     if (!BN_mod_exp(pub_key, dsa->params.g, prk, dsa->params.p, ctx))
  54         goto err;
  55     ret = 1;
  56 err:
  57     BN_clear_free(prk);
  58     return ret;
  59 }
  60
  61 static int dsa_keygen(DSA *dsa, int pairwise_test)
  62 {
  63     int ok = 0;
  64     BN_CTX *ctx = NULL;
  65     BIGNUM *pub_key = NULL, *priv_key = NULL;
  66
  67     if ((ctx = BN_CTX_new_ex(dsa->libctx)) == NULL)
  68         goto err;
  69
  70     if (dsa->priv_key == NULL) {
  71         if ((priv_key = BN_secure_new()) == NULL)
  72             goto err;
  73     } else {
  74         priv_key = dsa->priv_key;
  75     }
  76
  77     /*
  78      * For FFC FIPS 186-4 keygen
  79      * security strength s = 112,
  80      * Max Private key size N = len(q)
  81      */
  82     if (!ffc_generate_private_key(ctx, &dsa->params, BN_num_bits(dsa->params.q),
  83                                   MIN_STRENGTH, priv_key))
  84         goto err;
  85
  86     if (dsa->pub_key == NULL) {
  87         if ((pub_key = BN_new()) == NULL)
  88             goto err;
  89     } else {
  90         pub_key = dsa->pub_key;
  91     }
  92
  93     if (!dsa_generate_public_key(ctx, dsa, priv_key, pub_key))
  94         goto err;
  95
  96     dsa->priv_key = priv_key;
  97     dsa->pub_key = pub_key;
  98
  99 #ifdef FIPS_MODULE
 100     pairwise_test = 1;
 101 #endif /* FIPS_MODULE */
 102
 103     ok = 1;
 104     if (pairwise_test) {
 105         OSSL_CALLBACK *cb = NULL;
 106         void *cbarg = NULL;
 107
 108         OSSL_SELF_TEST_get_callback(dsa->libctx, &cb, &cbarg);
 109         ok = dsa_keygen_pairwise_test(dsa, cb, cbarg);
 110         if (!ok) {
 111             BN_free(dsa->pub_key);
 112             BN_clear_free(dsa->priv_key);
 113             BN_CTX_free(ctx);
 114             return ok;
 115         }
 116     }
 117     dsa->dirty_cnt++;
 118
 119  err:
 120     if (pub_key != dsa->pub_key)
 121         BN_free(pub_key);
 122     if (priv_key != dsa->priv_key)
 123         BN_free(priv_key);
 124     BN_CTX_free(ctx);
 125
 126     return ok;
 127 }
 128
 129 /*
 130  * FIPS 140-2 IG 9.9 AS09.33
 131  * Perform a sign/verify operation.
 132  */
 133 static int dsa_keygen_pairwise_test(DSA *dsa, OSSL_CALLBACK *cb, void *cbarg)
 134 {
 135     int ret = 0;
 136     unsigned char dgst[16] = {0};
 137     unsigned int dgst_len = (unsigned int)sizeof(dgst);
 138     DSA_SIG *sig = NULL;
 139     OSSL_SELF_TEST *st = NULL;
 140
 141     st = OSSL_SELF_TEST_new(cb, cbarg);
 142     if (st == NULL)
 143         goto err;
 144
 145     OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
 146                            OSSL_SELF_TEST_DESC_PCT_DSA);
 147
 148     sig = DSA_do_sign(dgst, (int)dgst_len, dsa);
 149     if (sig == NULL)
 150         goto err;
 151
 152     OSSL_SELF_TEST_oncorrupt_byte(st, dgst);
 153
 154     if (DSA_do_verify(dgst, dgst_len, sig, dsa) != 1)
 155         goto err;
 156
 157     ret = 1;
 158 err:
 159     OSSL_SELF_TEST_onend(st, ret);
 160     OSSL_SELF_TEST_free(st);
 161     DSA_SIG_free(sig);
 162     return ret;
 163 }