openssl/doc/man7/EVP_PKEY-DSA.pod
Shane Lontis b808665265 Update core_names.h fields and document most fields.
Renamed some values in core_names i.e Some DH specific names were changed to use DH instead of FFC.
Added some strings values related to RSA keys.
Moved set_params related docs out of EVP_PKEY_CTX_ctrl.pod into its own file.
Updated Keyexchange and signature code and docs.
Moved some common DSA/DH docs into a shared EVP_PKEY-FFC.pod.
Moved Ed25519.pod into EVP_SIGNATURE-ED25519.pod and reworked it.

Added some usage examples. As a result of the usage examples the following change was also made:
ec allows OSSL_PKEY_PARAM_USE_COFACTOR_ECDH as a settable gen parameter.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11610)
2020-05-26 13:53:07 +10:00

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=pod
=head1 NAME
EVP_PKEY-DSA, EVP_KEYMGMT-DSA - EVP_PKEY DSA keytype and algorithm support
=head1 DESCRIPTION
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 DSA parameters
The B<DSA> key type supports the FFC parameters (see
L<EVP_PKEY-FFC(7)/FFC parameters>).
=head2 DSA key generation parameters
The B<DSA> key type supports the FFC key generation parameters (see
L<EVP_PKEY-FFC(7)/FFC key generation parameters>
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.
=head1 EXAMPLES
An B<EVP_PKEY> context can be obtained by calling:
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_from_name(NULL, "DSA", NULL);
An B<DH> domain parameters key 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_gen(pctx, &param_key);
EVP_PKEY_CTX_free(pctx);
EVP_PKEY_print_params(bio_out, param_key, 0, NULL);
An 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_gen(gctx, &key);
EVP_PKEY_CTX_free(gctx);
EVP_PKEY_print_private(bio_out, key, 0, NULL);
=head1 CONFORMING TO
The following sections of FIPS 186-4:
=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_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.
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
L<https://www.openssl.org/source/license.html>.
=cut