# EVP_MAC-BLAKE2SMAC - The BLAKE2 EVP_MAC implementations - man(7ssl) - [phpMan]

[_EVP_MAC-BLAKE2_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPMAC-BLAKE2/7SSL/markdown)                           OpenSSL                          [_EVP_MAC-BLAKE2_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPMAC-BLAKE2/7SSL/markdown)

## NAME
       EVP_MAC-BLAKE2, EVP_MAC-BLAKE2BMAC, EVP_MAC-BLAKE2SMAC - The BLAKE2 EVP_MAC implementations

## DESCRIPTION
       Support for computing BLAKE2 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()**:

       "BLAKE2BMAC", "provider=default"
       "BLAKE2SMAC", "provider=default"

### Supported parameters
       The general description of these parameters can be found in "PARAMETERS" in [**EVP_MAC**(3)](https://www.chedong.com/phpMan.php/man/EVPMAC/3/markdown).

       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.  It may be at most 64 bytes for BLAKE2BMAC or 32 for BLAKE2SMAC and  at
           least  1  byte  in  both  cases.  Setting this parameter is identical to passing a _key_ to
           [**EVP_MAC_init**(3)](https://www.chedong.com/phpMan.php/man/EVPMACinit/3/markdown).

       "custom" (**OSSL_MAC_PARAM_CUSTOM**) <octet string>
           Sets the customization/personalization string.  It is an optional value  of  at  most  16
           bytes for BLAKE2BMAC or 8 for BLAKE2SMAC, and is empty by default.

       "salt" (**OSSL_MAC_PARAM_SALT**) <octet string>
           Sets  the  salt.   It  is  an  optional value of at most 16 bytes for BLAKE2BMAC or 8 for
           BLAKE2SMAC, and is empty by default.

       "size" (**OSSL_MAC_PARAM_SIZE**) <unsigned integer>
           Sets the MAC size.  It can be any number between 1 and 32 for EVP_MAC_BLAKE2S or  between
           1 and 64 for EVP_MAC_BLAKE2B.  It is 32 and 64 respectively by default.

       "block-size" (**OSSL_MAC_PARAM_BLOCK_SIZE**) <unsigned integer>
           Gets the MAC block size.  It is 64 for EVP_MAC_BLAKE2S and 128 for EVP_MAC_BLAKE2B.

## SEE ALSO
       [**EVP_MAC_CTX_get_params**(3)](https://www.chedong.com/phpMan.php/man/EVPMACCTXgetparams/3/markdown),    [**EVP_MAC_CTX_set_params**(3)](https://www.chedong.com/phpMan.php/man/EVPMACCTXsetparams/3/markdown),    "PARAMETERS"    in    [**EVP_MAC**(3)](https://www.chedong.com/phpMan.php/man/EVPMAC/3/markdown),
       [**OSSL_PARAM**(3)](https://www.chedong.com/phpMan.php/man/OSSLPARAM/3/markdown)

## HISTORY
       The macros and functions described here were added to OpenSSL 3.0.

## 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>>.

3.0.13                                       2026-07-29                         [_EVP_MAC-BLAKE2_(7SSL)](https://www.chedong.com/phpMan.php/man/EVPMAC-BLAKE2/7SSL/markdown)