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_MODE
  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_MODE
  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     if (!ffc_generate_private_key(ctx, &dsa->params, BN_num_bits(dsa->params.q),
  78                                   MIN_STRENGTH, priv_key))
  79         goto err;
  80
  81     if (dsa->pub_key == NULL) {
  82         if ((pub_key = BN_new()) == NULL)
  83             goto err;
  84     } else {
  85         pub_key = dsa->pub_key;
  86     }
  87
  88     if (!dsa_generate_public_key(ctx, dsa, priv_key, pub_key))
  89         goto err;
  90
  91     dsa->priv_key = priv_key;
  92     dsa->pub_key = pub_key;
  93
  94 #ifdef FIPS_MODE
  95     pairwise_test = 1;
  96 #endif /* FIPS_MODE */
  97
  98     ok = 1;
  99     if (pairwise_test) {
 100         OSSL_CALLBACK *cb = NULL;
 101         void *cbarg = NULL;
 102
 103         OSSL_SELF_TEST_get_callback(dsa->libctx, &cb, &cbarg);
 104         ok = dsa_keygen_pairwise_test(dsa, cb, cbarg);
 105         if (!ok) {
 106             BN_free(dsa->pub_key);
 107             BN_clear_free(dsa->priv_key);
 108             BN_CTX_free(ctx);
 109             return ok;
 110         }
 111     }
 112     dsa->dirty_cnt++;
 113
 114  err:
 115     if (pub_key != dsa->pub_key)
 116         BN_free(pub_key);
 117     if (priv_key != dsa->priv_key)
 118         BN_free(priv_key);
 119     BN_CTX_free(ctx);
 120
 121     return ok;
 122 }
 123
 124 /*
 125  * FIPS 140-2 IG 9.9 AS09.33
 126  * Perform a sign/verify operation.
 127  */
 128 static int dsa_keygen_pairwise_test(DSA *dsa, OSSL_CALLBACK *cb, void *cbarg)
 129 {
 130     int ret = 0;
 131     unsigned char dgst[16] = {0};
 132     unsigned int dgst_len = (unsigned int)sizeof(dgst);
 133     DSA_SIG *sig = NULL;
 134     OSSL_SELF_TEST *st = NULL;
 135
 136     st = OSSL_SELF_TEST_new(cb, cbarg);
 137     if (st == NULL)
 138         goto err;
 139
 140     OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
 141                            OSSL_SELF_TEST_DESC_PCT_DSA);
 142
 143     sig = DSA_do_sign(dgst, (int)dgst_len, dsa);
 144     if (sig == NULL)
 145         goto err;
 146
 147     OSSL_SELF_TEST_oncorrupt_byte(st, dgst);
 148
 149     if (DSA_do_verify(dgst, dgst_len, sig, dsa) != 1)
 150         goto err;
 151
 152     ret = 1;
 153 err:
 154     OSSL_SELF_TEST_onend(st, ret);
 155     OSSL_SELF_TEST_free(st);
 156     DSA_SIG_free(sig);
 157     return ret;
 158 }