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/*
* Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* DSA low level APIs are deprecated for public use, but still ok for
* internal use.
*/
#include "internal/deprecated.h"
#include <stdio.h>
#include <time.h>
#include "internal/cryptlib.h"
#include <openssl/bn.h>
#include <openssl/self_test.h>
#include "prov/providercommon.h"
#include "crypto/dsa.h"
#include "dsa_local.h"
#ifdef FIPS_MODULE
#define MIN_STRENGTH 112
#else
#define MIN_STRENGTH 80
#endif
static int dsa_keygen(DSA *dsa);
int DSA_generate_key(DSA *dsa)
{
#ifndef FIPS_MODULE
if (dsa->meth->dsa_keygen != NULL)
return dsa->meth->dsa_keygen(dsa);
#endif
return dsa_keygen(dsa);
}
int ossl_dsa_generate_public_key(BN_CTX *ctx, const DSA *dsa,
const BIGNUM *priv_key, BIGNUM *pub_key)
{
int ret = 0;
BIGNUM *prk = BN_new();
if (prk == NULL)
return 0;
BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
/* pub_key = g ^ priv_key mod p */
if (!BN_mod_exp(pub_key, dsa->params.g, prk, dsa->params.p, ctx))
goto err;
ret = 1;
err:
BN_clear_free(prk);
return ret;
}
#ifdef FIPS_MODULE
/*
* Refer: FIPS 140-3 IG 10.3.A Additional Comment 1
* Perform a KAT by duplicating the public key generation.
*
* NOTE: This issue requires a background understanding, provided in a separate
* document; the current IG 10.3.A AC1 is insufficient regarding the PCT for
* the key agreement scenario.
*
* Currently IG 10.3.A requires PCT in the mode of use prior to use of the
* key pair, citing the PCT defined in the associated standard. For key
* agreement, the only PCT defined in SP 800-56A is that of Section 5.6.2.4:
* the comparison of the original public key to a newly calculated public key.
*/
static int dsa_keygen_knownanswer_test(DSA *dsa, BN_CTX *ctx,
OSSL_CALLBACK *cb, void *cbarg)
{
int len, ret = 0;
OSSL_SELF_TEST *st = NULL;
unsigned char bytes[512] = { 0 };
BIGNUM *pub_key2 = BN_new();
if (pub_key2 == NULL)
return 0;
st = OSSL_SELF_TEST_new(cb, cbarg);
if (st == NULL)
goto err;
OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT_KAT,
OSSL_SELF_TEST_DESC_PCT_DSA);
if (!ossl_dsa_generate_public_key(ctx, dsa, dsa->priv_key, pub_key2))
goto err;
if (BN_num_bytes(pub_key2) > (int)sizeof(bytes))
goto err;
len = BN_bn2bin(pub_key2, bytes);
OSSL_SELF_TEST_oncorrupt_byte(st, bytes);
if (BN_bin2bn(bytes, len, pub_key2) != NULL)
ret = !BN_cmp(dsa->pub_key, pub_key2);
err:
OSSL_SELF_TEST_onend(st, ret);
OSSL_SELF_TEST_free(st);
BN_free(pub_key2);
return ret;
}
/*
* FIPS 140-2 IG 9.9 AS09.33
* Perform a sign/verify operation.
*/
static int dsa_keygen_pairwise_test(DSA *dsa, OSSL_CALLBACK *cb, void *cbarg)
{
int ret = 0;
unsigned char dgst[16] = { 0 };
unsigned int dgst_len = (unsigned int)sizeof(dgst);
DSA_SIG *sig = NULL;
OSSL_SELF_TEST *st = NULL;
st = OSSL_SELF_TEST_new(cb, cbarg);
if (st == NULL)
goto err;
OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
OSSL_SELF_TEST_DESC_PCT_DSA);
sig = DSA_do_sign(dgst, (int)dgst_len, dsa);
if (sig == NULL)
goto err;
OSSL_SELF_TEST_oncorrupt_byte(st, dgst);
if (DSA_do_verify(dgst, dgst_len, sig, dsa) != 1)
goto err;
ret = 1;
err:
OSSL_SELF_TEST_onend(st, ret);
OSSL_SELF_TEST_free(st);
DSA_SIG_free(sig);
return ret;
}
#endif /* FIPS_MODULE */
static int dsa_keygen(DSA *dsa)
{
int ok = 0;
BN_CTX *ctx = NULL;
BIGNUM *pub_key = NULL, *priv_key = NULL;
if ((ctx = BN_CTX_new_ex(dsa->libctx)) == NULL)
goto err;
if (dsa->priv_key == NULL) {
if ((priv_key = BN_secure_new()) == NULL)
goto err;
} else {
priv_key = dsa->priv_key;
}
/* Do a partial check for invalid p, q, g */
if (!ossl_ffc_params_simple_validate(dsa->libctx, &dsa->params,
FFC_PARAM_TYPE_DSA, NULL))
goto err;
/*
* For FFC FIPS 186-4 keygen
* security strength s = 112,
* Max Private key size N = len(q)
*/
if (!ossl_ffc_generate_private_key(ctx, &dsa->params,
BN_num_bits(dsa->params.q),
MIN_STRENGTH, priv_key))
goto err;
if (dsa->pub_key == NULL) {
if ((pub_key = BN_new()) == NULL)
goto err;
} else {
pub_key = dsa->pub_key;
}
if (!ossl_dsa_generate_public_key(ctx, dsa, priv_key, pub_key))
goto err;
dsa->priv_key = priv_key;
dsa->pub_key = pub_key;
ok = 1;
#ifdef FIPS_MODULE
{
OSSL_CALLBACK *cb = NULL;
void *cbarg = NULL;
OSSL_SELF_TEST_get_callback(dsa->libctx, &cb, &cbarg);
ok = dsa_keygen_pairwise_test(dsa, cb, cbarg)
&& dsa_keygen_knownanswer_test(dsa, ctx, cb, cbarg);
if (!ok) {
ossl_set_error_state(OSSL_SELF_TEST_TYPE_PCT);
BN_free(dsa->pub_key);
BN_clear_free(dsa->priv_key);
dsa->pub_key = NULL;
dsa->priv_key = NULL;
BN_CTX_free(ctx);
return ok;
}
}
#endif
dsa->dirty_cnt++;
err:
if (pub_key != dsa->pub_key)
BN_free(pub_key);
if (priv_key != dsa->priv_key)
BN_free(priv_key);
BN_CTX_free(ctx);
return ok;
}
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