EVP_MD-SHAKE(7ossl) OpenSSL EVP_MD-SHAKE(7ossl)
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 an Extendable Output Function (XOF), with a definition
similar to SHAKE, 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). Using the notation from NIST FIPS 202
(Section 6.2), we have KECCAK-KMAC-128(M, d) =
KECCAK[256](M || 00, d) (see the description of KMAC128 in Appendix
A of NIST SP 800-185).
KECCAK-KMAC-256
Known names are "KECCAK-KMAC-256" and "KECCAK-KMAC256". This is
used by EVP_MAC-KMAC256(7). Using the notation from NIST FIPS 202
(Section 6.2), we have KECCAK-KMAC-256(M, d) =
KECCAK[512](M || 00, d) (see the description of KMAC256 in Appendix
A of NIST SP 800-185).
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.
This parameter may be used when calling either EVP_DigestFinal_ex()
or EVP_DigestFinal(), since these functions were not designed to
handle variable length output. It is recommended to either use
EVP_DigestSqueeze() or EVP_DigestFinalXOF() instead.
NOTES
For SHAKE-128, to ensure the maximum security strength of 128 bits, the
output length passed to EVP_DigestFinalXOF() should be at least 32.
For SHAKE-256, to ensure the maximum security strength of 256 bits, the
output length passed to EVP_DigestFinalXOF() should be at least 64.
SEE ALSO
EVP_MD_CTX_set_params(3), provider-digest(7), OSSL_PROVIDER-default(7)
COPYRIGHT
Copyright 2020-2023 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>.
3.3.2 2024-09-04 EVP_MD-SHAKE(7ossl)
openssl 3.3.2 - Generated Tue Oct 1 13:29:27 CDT 2024