=head1 NAME
-EVP_PKEY-DSA, EVP_KEYMGMT-DSA, EVP_PKEY-DH, EVP_KEYMGMT-DH
-- EVP_PKEY DSA and DH keytype and algorithm support
+EVP_PKEY-DSA, EVP_KEYMGMT-DSA - EVP_PKEY DSA keytype and algorithm support
=head1 DESCRIPTION
-The B<DSA> and B<DH> keytypes are implemented in OpenSSL's default and FIPS
-providers.
-The implementations support the basic DSA and DH keys, containing the public
-and private keys I<pub> and I<priv> as well as the three domain parameters
-I<p>, I<q> and I<g>.
+For B<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 I<seed>, I<pcounter>
+and I<gindex> may need to be stored for validation purposes. For B<DSA> these
+fields are not stored in the ASN1 data so they need to be stored externally if
+validation is required.
-=head2 Common DSA / DH parameters
+=head2 DSA parameters
-In addition to the common parameters that all keytypes should support (see
-L<provider-keymgmt(7)/Common parameters>), the B<DSA> and B<DH> keytype
-implementations support the following.
+The B<DSA> key type supports the FFC parameters (see
+L<EVP_PKEY-FFC(7)/FFC parameters>).
-=over 4
+=head2 DSA key generation parameters
-=item "pub" (B<OSSL_PKEY_PARAM_PUB_KEY>) <unsigned integer>
+The B<DSA> key type supports the FFC key generation parameters (see
+L<EVP_PKEY-FFC(7)/FFC key generation parameters>
-The public key value.
+The following restrictions apply to the "pbits" field:
-=item "priv" (B<OSSL_PKEY_PARAM_PRIV_KEY>) <unsigned integer>
+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.
-The private key value.
+=head2 DSA key validation
-=item "p" (B<OSSL_PKEY_PARAM_FFC_P>) <unsigned integer>
+For DSA keys, L<EVP_PKEY_param_check(3)> behaves in the following way:
+The OpenSSL FIPS provider conforms to the rules within the FIPS186-4
+standard for FFC parameter validation. For backwards compatibility the OpenSSL
+default provider uses a much simpler check (see below) for parameter validation,
+unless the seed parameter is set.
-A DSA or Diffie-Hellman "p" value.
+For DSA keys, L<EVP_PKEY_param_check_quick(3)> behaves in the following way:
+A simple check of L and N and partial g is performed. The default provider
+also supports validation of legacy "fips186_2" keys.
-=item "q" (B<OSSL_PKEY_PARAM_FFC_Q>) <unsigned integer>
+For DSA keys, L<EVP_PKEY_public_check(3)>, L<EVP_PKEY_private_check(3)> and
+L<EVP_PKEY_pairwise_check(3)> the OpenSSL default and FIPS providers conform to
+the rules within SP800-56Ar3 for public, private and pairwise tests respectively.
-A DSA or Diffie-Hellman "q" value.
+=head1 EXAMPLES
-=item "g" (B<OSSL_PKEY_PARAM_FFC_G>) <unsigned integer>
+An B<EVP_PKEY> context can be obtained by calling:
-A DSA or Diffie-Hellman "g" value.
+ EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_from_name(NULL, "DSA", NULL);
+
+The B<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, ¶m_key);
+ EVP_PKEY_CTX_free(pctx);
+
+ EVP_PKEY_print_params(bio_out, param_key, 0, NULL);
+
+A B<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);
-=back
=head1 CONFORMING TO
-[TBA]
+The following sections of FIPS186-4:
+
+=over 4
+
+=item A.1.1.2 Generation of Probable Primes p and q Using an Approved Hash Function.
+
+=item A.2.3 Generation of canonical generator g.
+
+=item A.2.1 Unverifiable Generation of the Generator g.
+
+=back
=head1 SEE ALSO
-L<EVP_KEYMGMT(3)>, L<EVP_PKEY(3)>, L<provider-keymgmt(7)>,
-L<OSSL_PROVIDER-default(7)>, L<OSSL_PROVIDER-FIPS(7)>,
-L<EVP_SIGNATURE-DSA(7)>, L<EVP_KEYEXCH-DH(7)>
+L<EVP_PKEY-FFC(7)>,
+L<EVP_SIGNATURE-DSA(7)>
+L<EVP_PKEY(3)>,
+L<provider-keymgmt(7)>,
+L<EVP_KEYMGMT(3)>,
+L<OSSL_PROVIDER-default(7)>,
+L<OSSL_PROVIDER-FIPS(7)>
=head1 COPYRIGHT
-Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
+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
projects / openssl.git / blobdiff