mirror of https://github.com/openssl/openssl.git
108 lines
3.0 KiB
Plaintext
108 lines
3.0 KiB
Plaintext
=pod
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=head1 NAME
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EVP_PKEY-DSA, EVP_KEYMGMT-DSA - EVP_PKEY DSA keytype and algorithm support
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=head1 DESCRIPTION
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For B<DSA> the FIPS186-4 standard specifies that the values used for FFC
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parameter generation are also required for parameter validation.
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This means that optional FFC domain parameter values for I<seed>, I<pcounter>
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and I<gindex> may need to be stored for validation purposes. For B<DSA> these
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fields are not stored in the ASN1 data so they need to be stored externally if
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validation is required.
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=head2 DSA parameters
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The B<DSA> key type supports the FFC parameters (see
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L<EVP_PKEY-FFC(7)/FFC parameters>).
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=head2 DSA key generation parameters
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The B<DSA> key type supports the FFC key generation parameters (see
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L<EVP_PKEY-FFC(7)/FFC key generation parameters>
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The following restrictions apply to the "pbits" field:
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For "fips186_4" this must be either 2048 or 3072.
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For "fips186_2" this must be 1024.
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For "group" this can be any one of 2048, 3072, 4096, 6144 or 8192.
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=head1 EXAMPLES
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An B<EVP_PKEY> context can be obtained by calling:
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EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_from_name(NULL, "DSA", NULL);
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An B<DH> domain parameters key can be generated by calling:
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unsigned int pbits = 2048;
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unsigned int qbits = 256;
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int gindex = 1;
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OSSL_PARAM params[5];
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EVP_PKEY *param_key = NULL;
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EVP_PKEY_CTX *pctx = NULL;
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pctx = EVP_PKEY_CTX_new_from_name(NULL, "DSA", NULL);
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EVP_PKEY_paramgen_init(pctx);
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params[0] = OSSL_PARAM_construct_uint("pbits", &pbits);
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params[1] = OSSL_PARAM_construct_uint("qbits", &qbits);
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params[2] = OSSL_PARAM_construct_int("gindex", &gindex);
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params[3] = OSSL_PARAM_construct_utf8_string("digest", "SHA384", 0);
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params[4] = OSSL_PARAM_construct_end();
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EVP_PKEY_CTX_set_params(pctx, params);
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EVP_PKEY_gen(pctx, ¶m_key);
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EVP_PKEY_CTX_free(pctx);
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EVP_PKEY_print_params(bio_out, param_key, 0, NULL);
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An B<DSA> key can be generated using domain parameters by calling:
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EVP_PKEY *key = NULL;
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EVP_PKEY_CTX *gctx = NULL;
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gctx = EVP_PKEY_CTX_new_from_pkey(NULL, param_key, NULL);
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EVP_PKEY_keygen_init(gctx);
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EVP_PKEY_gen(gctx, &key);
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EVP_PKEY_CTX_free(gctx);
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EVP_PKEY_print_private(bio_out, key, 0, NULL);
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=head1 CONFORMING TO
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The following sections of FIPS 186-4:
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=over 4
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=item A.1.1.2 Generation of Probable Primes p and q Using an Approved Hash Function.
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=item A.2.3 Generation of canonical generator g.
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=item A.2.1 Unverifiable Generation of the Generator g.
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=back
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=head1 SEE ALSO
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L<EVP_PKEY-FFC(7)>,
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L<EVP_SIGNATURE-DSA(7)>
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L<EVP_PKEY(3)>,
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L<provider-keymgmt(7)>,
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L<EVP_KEYMGMT(3)>,
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L<OSSL_PROVIDER-default(7)>,
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L<OSSL_PROVIDER-FIPS(7)>
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=head1 COPYRIGHT
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Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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