NAME

       EVP_MD-SHAKE, EVP_MD-KECCAK-KMAC - The SHAKE / KECCAK family EVP_MD implementations

DESCRIPTION

       Support for computing SHAKE or KECCAK-KMAC digests through the EVP_MD API.

       KECCAK-KMAC is a special digest that's used by the KMAC EVP_MAC implementation (see
       EVP_MAC-KMAC(7)).

   Identities
       This implementation is available in the FIPS provider as well as the default provider, and
       includes the following varieties:

       KECCAK-KMAC-128
           Known names are "KECCAK-KMAC-128" and "KECCAK-KMAC128" This is used by
           EVP_MAC-KMAC128(7)

       KECCAK-KMAC-256
           Known names are "KECCAK-KMAC-256" and "KECCAK-KMAC256" This is used by
           EVP_MAC-KMAC256(7)

       SHAKE-128
           Known names are "SHAKE-128" and "SHAKE128"

       SHAKE-256
           Known names are "SHAKE-256" and "SHAKE256"

   Gettable Parameters
       This implementation supports the common gettable parameters described in EVP_MD-common(7).

   Settable Context Parameters
       These implementations support the following OSSL_PARAM(3) entries, settable for an
       EVP_MD_CTX with EVP_MD_CTX_set_params(3):

       "xoflen" (OSSL_DIGEST_PARAM_XOFLEN) <unsigned integer>
           Sets the digest length for extendable output functions.  The length of the "xoflen"
           parameter should not exceed that of a size_t.

           For backwards compatibility reasons the default xoflen length for SHAKE-128 is 16
           (bytes) which results in a security strength of only 64 bits. To ensure the maximum
           security strength of 128 bits, the xoflen should be set to at least 32.

           For backwards compatibility reasons the default xoflen length for SHAKE-256 is 32
           (bytes) which results in a security strength of only 128 bits. To ensure the maximum
           security strength of 256 bits, the xoflen should be set to at least 64.

SEE ALSO

       EVP_MD_CTX_set_params(3), provider-digest(7), OSSL_PROVIDER-default(7)

COPYRIGHT

       Copyright 2020-2022 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>.