EVP_MAC-KMAC(7) - NetBSD Manual Pages

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EVP_MAC-KMAC(7)                     OpenSSL                    EVP_MAC-KMAC(7)




NAME

       EVP_MAC-KMAC, EVP_MAC-KMAC128, EVP_MAC-KMAC256 - The KMAC EVP_MAC
       implementations


DESCRIPTION

       Support for computing KMAC MACs through the EVP_MAC API.

   Identity
       These implementations are identified with one of these names and
       properties, to be used with EVP_MAC_fetch():

       "KMAC-128", "provider=default" or "provider=fips"
       "KMAC-256", "provider=default" or "provider=fips"

   Supported parameters
       The general description of these parameters can be found in
       "PARAMETERS" in EVP_MAC(3).

       All these parameters (except for "block-size") can be set with
       EVP_MAC_CTX_set_params().  Furthermore, the "size" parameter can be
       retrieved with EVP_MAC_CTX_get_params(), or with
       EVP_MAC_CTX_get_mac_size().  The length of the "size" parameter should
       not exceed that of a size_t.  Likewise, the "block-size" parameter can
       be retrieved with EVP_MAC_CTX_get_params(), or with
       EVP_MAC_CTX_get_block_size().

       "key" (OSSL_MAC_PARAM_KEY) <octet string>
           Sets the MAC key.  Setting this parameter is identical to passing a
           key to EVP_MAC_init(3).  The length of the key (in bytes) must be
           in the range 4...512.

       "custom" (OSSL_MAC_PARAM_CUSTOM) <octet string>
           Sets the customization string.  It is an optional value with a
           length of at most 512 bytes, and is empty by default.

       "size" (OSSL_MAC_PARAM_SIZE) <unsigned integer>
           Sets the MAC size.  By default, it is 32 for "KMAC-128" and 64 for
           "KMAC-256".

       "block-size" (OSSL_MAC_PARAM_BLOCK_SIZE) <unsigned integer>
           Gets the MAC block size.  It is 168 for "KMAC-128" and 136 for
           "KMAC-256".

       "xof" (OSSL_MAC_PARAM_XOF) <integer>
           The "xof" parameter value is expected to be 1 or 0. Use 1 to enable
           XOF mode.  The default value is 0.

       The "custom" parameter must be set as part of or before the
       EVP_MAC_init() call.  The "xof" and "size" parameters can be set at any
       time before EVP_MAC_final().  The "key" parameter is set as part of the
       EVP_MAC_init() call, but can be set before it instead.


EXAMPLES

         #include <openssl/evp.h>
         #include <openssl/params.h>

         static int do_kmac(const unsigned char *in, size_t in_len,
                            const unsigned char *key, size_t key_len,
                            const unsigned char *custom, size_t custom_len,
                            int xof_enabled, unsigned char *out, int out_len)
         {
             EVP_MAC_CTX *ctx = NULL;
             EVP_MAC *mac = NULL;
             OSSL_PARAM params[4], *p;
             int ret = 0;
             size_t l = 0;

             mac = EVP_MAC_fetch(NULL, "KMAC-128", NULL);
             if (mac == NULL)
                 goto err;
             ctx = EVP_MAC_CTX_new(mac);
             /* The mac can be freed after it is used by EVP_MAC_CTX_new */
             EVP_MAC_free(mac);
             if (ctx == NULL)
                 goto err;

             /*
              * Setup parameters required before calling EVP_MAC_init()
              * The parameters OSSL_MAC_PARAM_XOF and OSSL_MAC_PARAM_SIZE may also be
              * used at this point.
              */
             p = params;
             *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
                                                      (void *)key, key_len);
             if (custom != NULL && custom_len != 0)
               *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
                                                        (void *)custom, custom_len);
             *p = OSSL_PARAM_construct_end();
             if (!EVP_MAC_CTX_set_params(ctx, params))
                 goto err;

             if (!EVP_MAC_init(ctx))
                 goto err;

             /*
              * Note: the following optional parameters can be set any time
              * before EVP_MAC_final().
              */
             p = params;
             *p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_XOF, &xof_enabled);
             *p++ = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_SIZE, &out_len);
             *p = OSSL_PARAM_construct_end();
             if (!EVP_MAC_CTX_set_params(ctx, params))
                 goto err;

             /* The update may be called multiple times here for streamed input */
             if (!EVP_MAC_update(ctx, in, in_len))
                 goto err;
             if (!EVP_MAC_final(ctx, out, &l, out_len))
                 goto err;
             ret = 1;
         err:
             EVP_MAC_CTX_free(ctx);
             return ret;
         }


SEE ALSO

       EVP_MAC_CTX_get_params(3), EVP_MAC_CTX_set_params(3), "PARAMETERS" in
       EVP_MAC(3), OSSL_PARAM(3)


COPYRIGHT

       Copyright 2018-2021 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
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.



3.0.15                            2024-09-03                   EVP_MAC-KMAC(7)