1 /*
2 * Copyright 1995-2023 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 "prov/providercommon.h"
22 #include "crypto/dsa.h"
23 #include "dsa_local.h"
24
25 #ifdef FIPS_MODULE
26 # define MIN_STRENGTH 112
27 #else
28 # define MIN_STRENGTH 80
29 #endif
30
31 static int dsa_keygen(DSA *dsa);
32
DSA_generate_key(DSA * dsa)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);
40 }
41
ossl_dsa_generate_public_key(BN_CTX * ctx,const DSA * dsa,const BIGNUM * priv_key,BIGNUM * pub_key)42 int ossl_dsa_generate_public_key(BN_CTX *ctx, const DSA *dsa,
43 const BIGNUM *priv_key, 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 #ifdef FIPS_MODULE
62 /*
63 * Refer: FIPS 140-3 IG 10.3.A Additional Comment 1
64 * Perform a KAT by duplicating the public key generation.
65 *
66 * NOTE: This issue requires a background understanding, provided in a separate
67 * document; the current IG 10.3.A AC1 is insufficient regarding the PCT for
68 * the key agreement scenario.
69 *
70 * Currently IG 10.3.A requires PCT in the mode of use prior to use of the
71 * key pair, citing the PCT defined in the associated standard. For key
72 * agreement, the only PCT defined in SP 800-56A is that of Section 5.6.2.4:
73 * the comparison of the original public key to a newly calculated public key.
74 */
dsa_keygen_knownanswer_test(DSA * dsa,BN_CTX * ctx,OSSL_CALLBACK * cb,void * cbarg)75 static int dsa_keygen_knownanswer_test(DSA *dsa, BN_CTX *ctx,
76 OSSL_CALLBACK *cb, void *cbarg)
77 {
78 int len, ret = 0;
79 OSSL_SELF_TEST *st = NULL;
80 unsigned char bytes[512] = {0};
81 BIGNUM *pub_key2 = BN_new();
82
83 if (pub_key2 == NULL)
84 return 0;
85
86 st = OSSL_SELF_TEST_new(cb, cbarg);
87 if (st == NULL)
88 goto err;
89
90 OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT_KAT,
91 OSSL_SELF_TEST_DESC_PCT_DSA);
92
93 if (!ossl_dsa_generate_public_key(ctx, dsa, dsa->priv_key, pub_key2))
94 goto err;
95
96 if (BN_num_bytes(pub_key2) > (int)sizeof(bytes))
97 goto err;
98 len = BN_bn2bin(pub_key2, bytes);
99 OSSL_SELF_TEST_oncorrupt_byte(st, bytes);
100 if (BN_bin2bn(bytes, len, pub_key2) != NULL)
101 ret = !BN_cmp(dsa->pub_key, pub_key2);
102
103 err:
104 OSSL_SELF_TEST_onend(st, ret);
105 OSSL_SELF_TEST_free(st);
106 BN_free(pub_key2);
107 return ret;
108 }
109
110 /*
111 * FIPS 140-2 IG 9.9 AS09.33
112 * Perform a sign/verify operation.
113 */
dsa_keygen_pairwise_test(DSA * dsa,OSSL_CALLBACK * cb,void * cbarg)114 static int dsa_keygen_pairwise_test(DSA *dsa, OSSL_CALLBACK *cb, void *cbarg)
115 {
116 int ret = 0;
117 unsigned char dgst[16] = {0};
118 unsigned int dgst_len = (unsigned int)sizeof(dgst);
119 DSA_SIG *sig = NULL;
120 OSSL_SELF_TEST *st = NULL;
121
122 st = OSSL_SELF_TEST_new(cb, cbarg);
123 if (st == NULL)
124 goto err;
125
126 OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
127 OSSL_SELF_TEST_DESC_PCT_DSA);
128
129 sig = DSA_do_sign(dgst, (int)dgst_len, dsa);
130 if (sig == NULL)
131 goto err;
132
133 OSSL_SELF_TEST_oncorrupt_byte(st, dgst);
134
135 if (DSA_do_verify(dgst, dgst_len, sig, dsa) != 1)
136 goto err;
137
138 ret = 1;
139 err:
140 OSSL_SELF_TEST_onend(st, ret);
141 OSSL_SELF_TEST_free(st);
142 DSA_SIG_free(sig);
143 return ret;
144 }
145 #endif /* FIPS_MODULE */
146
dsa_keygen(DSA * dsa)147 static int dsa_keygen(DSA *dsa)
148 {
149 int ok = 0;
150 BN_CTX *ctx = NULL;
151 BIGNUM *pub_key = NULL, *priv_key = NULL;
152
153 if ((ctx = BN_CTX_new_ex(dsa->libctx)) == NULL)
154 goto err;
155
156 if (dsa->priv_key == NULL) {
157 if ((priv_key = BN_secure_new()) == NULL)
158 goto err;
159 } else {
160 priv_key = dsa->priv_key;
161 }
162
163 /* Do a partial check for invalid p, q, g */
164 if (!ossl_ffc_params_simple_validate(dsa->libctx, &dsa->params,
165 FFC_PARAM_TYPE_DSA, NULL))
166 goto err;
167
168 /*
169 * For FFC FIPS 186-4 keygen
170 * security strength s = 112,
171 * Max Private key size N = len(q)
172 */
173 if (!ossl_ffc_generate_private_key(ctx, &dsa->params,
174 BN_num_bits(dsa->params.q),
175 MIN_STRENGTH, priv_key))
176 goto err;
177
178 if (dsa->pub_key == NULL) {
179 if ((pub_key = BN_new()) == NULL)
180 goto err;
181 } else {
182 pub_key = dsa->pub_key;
183 }
184
185 if (!ossl_dsa_generate_public_key(ctx, dsa, priv_key, pub_key))
186 goto err;
187
188 dsa->priv_key = priv_key;
189 dsa->pub_key = pub_key;
190
191 ok = 1;
192 #ifdef FIPS_MODULE
193 {
194 OSSL_CALLBACK *cb = NULL;
195 void *cbarg = NULL;
196
197 OSSL_SELF_TEST_get_callback(dsa->libctx, &cb, &cbarg);
198 ok = dsa_keygen_pairwise_test(dsa, cb, cbarg)
199 && dsa_keygen_knownanswer_test(dsa, ctx, cb, cbarg);
200 if (!ok) {
201 ossl_set_error_state(OSSL_SELF_TEST_TYPE_PCT);
202 BN_free(dsa->pub_key);
203 BN_clear_free(dsa->priv_key);
204 dsa->pub_key = NULL;
205 dsa->priv_key = NULL;
206 BN_CTX_free(ctx);
207 return ok;
208 }
209 }
210 #endif
211 dsa->dirty_cnt++;
212
213 err:
214 if (pub_key != dsa->pub_key)
215 BN_free(pub_key);
216 if (priv_key != dsa->priv_key)
217 BN_free(priv_key);
218 BN_CTX_free(ctx);
219
220 return ok;
221 }
222
