# phpman > man > EVP_KEYMGMT-DSA(7)

[EVP_PKEY-DSA(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-DSA/7SSL/markdown)                             OpenSSL                            [EVP_PKEY-DSA(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-DSA/7SSL/markdown)



## NAME
       EVP_PKEY-DSA, EVP_KEYMGMT-DSA - EVP_PKEY DSA keytype and algorithm support

## DESCRIPTION
       For **DSA** the FIPS186-4 standard specifies that the values used for FFC parameter generation
       are also required for parameter validation.  This means that optional FFC domain parameter
       values for _seed_, _pcounter_ and _gindex_ may need to be stored for validation purposes. For **DSA**
       these fields are not stored in the ASN1 data so they need to be stored externally if
       validation is required.

### DSA parameters
       The **DSA** key type supports the FFC parameters (see "FFC parameters" in **EVP**___**[PKEY-FFC**(7)](https://www.chedong.com/phpMan.php/man/PKEY-FFC/7/markdown)).

### DSA key generation parameters
       The **DSA** key type supports the FFC key generation parameters (see "FFC key generation
       parameters" in **EVP**___**[PKEY-FFC**(7)](https://www.chedong.com/phpMan.php/man/PKEY-FFC/7/markdown)

       The following restrictions apply to the "pbits" field:

       For "fips186_4" this must be either 2048 or 3072.  For "fips186_2" this must be 1024.  For
       "group" this can be any one of 2048, 3072, 4096, 6144 or 8192.

## EXAMPLES
       An **EVP**___**PKEY** context can be obtained by calling:

           EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_from_name(NULL, "DSA", NULL);

       The **DSA** domain parameters can be generated by calling:

           unsigned int pbits = 2048;
           unsigned int qbits = 256;
           int gindex = 1;
           OSSL_PARAM params[5];
           EVP_PKEY *param_key = NULL;
           EVP_PKEY_CTX *pctx = NULL;

           pctx = EVP_PKEY_CTX_new_from_name(NULL, "DSA", NULL);
           EVP_PKEY_paramgen_init(pctx);

           params[0] = OSSL_PARAM_construct_uint("pbits", &pbits);
           params[1] = OSSL_PARAM_construct_uint("qbits", &qbits);
           params[2] = OSSL_PARAM_construct_int("gindex", &gindex);
           params[3] = OSSL_PARAM_construct_utf8_string("digest", "SHA384", 0);
           params[4] = OSSL_PARAM_construct_end();
           EVP_PKEY_CTX_set_params(pctx, params);

           EVP_PKEY_generate(pctx, &param_key);
           EVP_PKEY_CTX_free(pctx);

           EVP_PKEY_print_params(bio_out, param_key, 0, NULL);

       A **DSA** key can be generated using domain parameters by calling:

           EVP_PKEY *key = NULL;
           EVP_PKEY_CTX *gctx = NULL;

           gctx = EVP_PKEY_CTX_new_from_pkey(NULL, param_key, NULL);
           EVP_PKEY_keygen_init(gctx);
           EVP_PKEY_generate(gctx, &key);
           EVP_PKEY_CTX_free(gctx);
           EVP_PKEY_print_private(bio_out, key, 0, NULL);

## CONFORMING TO
       The following sections of FIPS 186-4:

       A.1.1.2 Generation of Probable Primes p and q Using an Approved Hash Function.
       A.2.3 Generation of canonical generator g.
       A.2.1 Unverifiable Generation of the Generator g.

## SEE ALSO
       **EVP**___**[PKEY-FFC**(7)](https://www.chedong.com/phpMan.php/man/PKEY-FFC/7/markdown), **EVP**___**[SIGNATURE-DSA**(7)](https://www.chedong.com/phpMan.php/man/SIGNATURE-DSA/7/markdown) **EVP**___**[PKEY**(3)](https://www.chedong.com/phpMan.php/man/PKEY/3/markdown), [**provider-keymgmt**(7)](https://www.chedong.com/phpMan.php/man/provider-keymgmt/7/markdown), **EVP**___**[KEYMGMT**(3)](https://www.chedong.com/phpMan.php/man/KEYMGMT/3/markdown),
       **OSSL**___**[PROVIDER-default**(7)](https://www.chedong.com/phpMan.php/man/PROVIDER-default/7/markdown), **OSSL**___**[PROVIDER-FIPS**(7)](https://www.chedong.com/phpMan.php/man/PROVIDER-FIPS/7/markdown)

## COPYRIGHT
       Copyright 2020-2021 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>>.



3.0.2                                        2026-06-02                           [EVP_PKEY-DSA(7SSL)](https://www.chedong.com/phpMan.php/man/EVPPKEY-DSA/7SSL/markdown)