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.\"
.IX Title "EVP_MD-SHAKE 7"
.TH EVP_MD-SHAKE 7 "2023-05-07" "3.0.9" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
EVP_MD\-SHAKE, EVP_MD\-KECCAK\-KMAC
\&\- The SHAKE / KECCAK family EVP_MD implementations
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Support for computing \s-1SHAKE\s0 or KECCAK-KMAC digests through the
\&\fB\s-1EVP_MD\s0\fR \s-1API.\s0
.PP
KECCAK-KMAC is a special digest that's used by the \s-1KMAC EVP_MAC\s0
implementation (see \s-1\fBEVP_MAC\-KMAC\s0\fR\|(7)).
.SS "Identities"
.IX Subsection "Identities"
This implementation is available in the \s-1FIPS\s0 provider as well as the default
provider, and includes the following varieties:
.IP "\s-1KECCAK\-KMAC\-128\s0" 4
.IX Item "KECCAK-KMAC-128"
Known names are \*(L"\s-1KECCAK\-KMAC\-128\*(R"\s0 and \*(L"\s-1KECCAK\-KMAC128\*(R"\s0
This is used by \s-1\fBEVP_MAC\-KMAC128\s0\fR\|(7)
.IP "\s-1KECCAK\-KMAC\-256\s0" 4
.IX Item "KECCAK-KMAC-256"
Known names are \*(L"\s-1KECCAK\-KMAC\-256\*(R"\s0 and \*(L"\s-1KECCAK\-KMAC256\*(R"\s0
This is used by \s-1\fBEVP_MAC\-KMAC256\s0\fR\|(7)
.IP "\s-1SHAKE\-128\s0" 4
.IX Item "SHAKE-128"
Known names are \*(L"\s-1SHAKE\-128\*(R"\s0 and \*(L"\s-1SHAKE128\*(R"\s0
.IP "\s-1SHAKE\-256\s0" 4
.IX Item "SHAKE-256"
Known names are \*(L"\s-1SHAKE\-256\*(R"\s0 and \*(L"\s-1SHAKE256\*(R"\s0
.SS "Gettable Parameters"
.IX Subsection "Gettable Parameters"
This implementation supports the common gettable parameters described
in \fBEVP_MD\-common\fR\|(7).
.SS "Settable Context Parameters"
.IX Subsection "Settable Context Parameters"
These implementations support the following \s-1\fBOSSL_PARAM\s0\fR\|(3) entries,
settable for an \fB\s-1EVP_MD_CTX\s0\fR with \fBEVP_MD_CTX_set_params\fR\|(3):
.ie n .IP """xoflen"" (\fB\s-1OSSL_DIGEST_PARAM_XOFLEN\s0\fR) <unsigned integer>" 4
.el .IP "``xoflen'' (\fB\s-1OSSL_DIGEST_PARAM_XOFLEN\s0\fR) <unsigned integer>" 4
.IX Item "xoflen (OSSL_DIGEST_PARAM_XOFLEN) <unsigned integer>"
Sets the digest length for extendable output functions.
The length of the \*(L"xoflen\*(R" parameter should not exceed that of a \fBsize_t\fR.
.Sp
For backwards compatibility reasons the default xoflen length for \s-1SHAKE\-128\s0 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.
.Sp
For backwards compatibility reasons the default xoflen length for \s-1SHAKE\-256\s0 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.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBEVP_MD_CTX_set_params\fR\|(3), \fBprovider\-digest\fR\|(7), \fBOSSL_PROVIDER\-default\fR\|(7)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2020\-2022 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.