155 lines
4.5 KiB
Plaintext
155 lines
4.5 KiB
Plaintext
=pod
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=head1 NAME
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EVP_MAC-KMAC, EVP_MAC-KMAC128, EVP_MAC-KMAC256
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- The KMAC EVP_MAC implementations
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=head1 DESCRIPTION
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Support for computing KMAC MACs through the B<EVP_MAC> API.
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=head2 Identity
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These implementations are identified with one of these names and
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properties, to be used with EVP_MAC_fetch():
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=over 4
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=item "KMAC-128", "provider=default" or "provider=fips"
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=item "KMAC-256", "provider=default" or "provider=fips"
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=back
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=head2 Supported parameters
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The general description of these parameters can be found in
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L<EVP_MAC(3)/PARAMETERS>.
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All these parameters (except for "block-size") can be set with
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EVP_MAC_CTX_set_params().
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Furthermore, the "size" parameter can be retrieved with
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EVP_MAC_CTX_get_params(), or with EVP_MAC_CTX_get_mac_size().
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The length of the "size" parameter should not exceed that of a B<size_t>.
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Likewise, the "block-size" parameter can be retrieved with
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EVP_MAC_CTX_get_params(), or with EVP_MAC_CTX_get_block_size().
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=over 4
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=item "key" (B<OSSL_MAC_PARAM_KEY>) <octet string>
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Sets the MAC key.
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Setting this parameter is identical to passing a I<key> to L<EVP_MAC_init(3)>.
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The length of the key (in bytes) must be in the range 4...512.
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=item "custom" (B<OSSL_MAC_PARAM_CUSTOM>) <octet string>
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Sets the customization string.
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It is an optional value with a length of at most 512 bytes, and is
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empty by default.
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=item "size" (B<OSSL_MAC_PARAM_SIZE>) <unsigned integer>
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Sets the MAC size.
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By default, it is 32 for C<KMAC-128> and 64 for C<KMAC-256>.
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=item "block-size" (B<OSSL_MAC_PARAM_BLOCK_SIZE>) <unsigned integer>
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Gets the MAC block size.
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It is 168 for C<KMAC-128> and 136 for C<KMAC-256>.
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=item "xof" (B<OSSL_MAC_PARAM_XOF>) <integer>
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The "xof" parameter value is expected to be 1 or 0. Use 1 to enable XOF mode.
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The default value is 0.
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=back
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The "custom" parameter must be set as part of or before the EVP_MAC_init() call.
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The "xof" and "size" parameters can be set at any time before EVP_MAC_final().
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The "key" parameter is set as part of the EVP_MAC_init() call, but can be
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set before it instead.
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=head1 EXAMPLES
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#include <openssl/evp.h>
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#include <openssl/params.h>
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static int do_kmac(const unsigned char *in, size_t in_len,
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const unsigned char *key, size_t key_len,
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const unsigned char *custom, size_t custom_len,
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int xof_enabled, unsigned char *out, int out_len)
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{
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EVP_MAC_CTX *ctx = NULL;
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EVP_MAC *mac = NULL;
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OSSL_PARAM params[4], *p;
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int ret = 0;
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size_t l = 0;
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mac = EVP_MAC_fetch(NULL, "KMAC-128", NULL);
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if (mac == NULL)
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goto err;
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ctx = EVP_MAC_CTX_new(mac);
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/* The mac can be freed after it is used by EVP_MAC_CTX_new */
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EVP_MAC_free(mac);
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if (ctx == NULL)
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goto err;
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/*
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* Setup parameters required before calling EVP_MAC_init()
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* The parameters OSSL_MAC_PARAM_XOF and OSSL_MAC_PARAM_SIZE may also be
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* used at this point.
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*/
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p = params;
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
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(void *)key, key_len);
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if (custom != NULL && custom_len != 0)
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
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(void *)custom, custom_len);
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*p = OSSL_PARAM_construct_end();
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if (!EVP_MAC_CTX_set_params(ctx, params))
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goto err;
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if (!EVP_MAC_init(ctx))
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goto err;
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/*
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* Note: the following optional parameters can be set any time
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* before EVP_MAC_final().
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*/
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p = params;
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*p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_XOF, &xof_enabled);
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*p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_SIZE, &out_len);
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*p = OSSL_PARAM_construct_end();
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if (!EVP_MAC_CTX_set_params(ctx, params))
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goto err;
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/* The update may be called multiple times here for streamed input */
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if (!EVP_MAC_update(ctx, in, in_len))
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goto err;
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if (!EVP_MAC_final(ctx, out, &l, out_len))
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goto err;
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ret = 1;
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err:
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EVP_MAC_CTX_free(ctx);
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return ret;
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}
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=head1 SEE ALSO
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L<EVP_MAC_CTX_get_params(3)>, L<EVP_MAC_CTX_set_params(3)>,
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L<EVP_MAC(3)/PARAMETERS>, L<OSSL_PARAM(3)>
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=head1 COPYRIGHT
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Copyright 2018-2023 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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