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11a1b341f3
We rename these function to EVP_PKEY_CTX_get_group_name and EVP_PKEY_CTX_set_group_name so that they can be used for other algorithms other than EC. Reviewed-by: Shane Lontis <shane.lontis@oracle.com> (Merged from https://github.com/openssl/openssl/pull/11914)
129 lines
3.5 KiB
Plaintext
129 lines
3.5 KiB
Plaintext
=pod
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=head1 NAME
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EVP_PKEY-EC,
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EVP_KEYMGMT-EC
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- EVP_PKEY EC keytype and algorithm support
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=head1 DESCRIPTION
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The B<EC> keytype is implemented in OpenSSL's default provider.
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=head2 Common EC parameters
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The following Import/Export types are available for the built-in EC algorithm:
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=over 4
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=item "group-name" (B<OSSL_PKEY_PARAM_GROUP_NAME>) <utf8 string>
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The curve name.
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=item "use-cofactor-flag" (B<OSSL_PKEY_PARAM_USE_COFACTOR_ECDH>) <integer>
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Enable Cofactor DH (ECC CDH) if this value is 1, otherwise it uses normal EC DH
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if the value is zero. The cofactor variant multiplies the shared secret by the
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EC curve's cofactor (note for some curves the cofactor is 1).
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See also L<EVP_KEYEXCH-ECDH(7)> for the related
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B<OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE> parameter that can be set on a
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per-operation basis.
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=item "pub" (B<OSSL_PKEY_PARAM_PUB_KEY>) <octet string>
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The public key value in EC point format.
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=item "priv" (B<OSSL_PKEY_PARAM_PRIV_KEY>) <unsigned integer>
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The private key value.
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=item "tls-encoded-pt" (B<OSSL_PKEY_PARAM_TLS_ENCODED_PT>) <octet string>
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Used for getting and setting the encoding of the EC public key used in key
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exchange message for the TLS protocol.
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=back
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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 =
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EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
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An B<EVP_PKEY> ECDSA or ECDH key can be generated with a "P-256" named group by
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calling:
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EVP_PKEY *key = NULL;
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OSSL_PARAM params[2];
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EVP_PKEY_CTX *gctx =
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EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
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EVP_PKEY_keygen_init(gctx);
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params[0] = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_GROUP_NAME,
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"P-256", 0);
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params[1] = OSSL_PARAM_construct_end();
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EVP_PKEY_CTX_set_params(gctx, params);
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EVP_PKEY_gen(gctx, &key);
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EVP_PKEY_print_private(bio_out, key, 0, NULL);
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...
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EVP_PKEY_free(key);
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EVP_PKEY_CTX_free(gctx);
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An B<EVP_PKEY> EC CDH (Cofactor Diffie-Hellman) key can be generated with a
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"K-571" named group by calling:
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int use_cdh = 1;
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EVP_PKEY *key = NULL;
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OSSL_PARAM params[3];
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EVP_PKEY_CTX *gctx =
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EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
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EVP_PKEY *key = NULL;
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OSSL_PARAM params[3];
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EVP_PKEY_CTX *gctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
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EVP_PKEY_keygen_init(gctx);
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params[0] = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_GROUP_NAME,
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"K-571", 0);
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/*
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* This curve has a cofactor that is not 1 - so setting CDH mode changes
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* the behaviour. For many curves the cofactor is 1 - so setting this has
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* no effect.
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*/
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params[1] = OSSL_PARAM_construct_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH,
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&use_cdh);
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params[2] = OSSL_PARAM_construct_end();
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EVP_PKEY_CTX_set_params(gctx, params);
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EVP_PKEY_gen(gctx, &key);
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EVP_PKEY_print_private(bio_out, key, 0, NULL);
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...
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EVP_PKEY_free(key);
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EVP_PKEY_CTX_free(gctx);
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=head1 SEE ALSO
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L<EVP_KEYMGMT(3)>,
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L<EVP_PKEY(3)>,
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L<provider-keymgmt(7)>,
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L<EVP_SIGNATURE-ECDSA(7)>,
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L<EVP_KEYEXCH-ECDH(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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