Android_verify/third_party/android-libs/share/man/man7/EVP_MD-SHAKE.7ossl

.\" Automatically generated by Pod::Man 4.14 (Pod::Simple 3.42)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
.    ds C`
.    ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is >0, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{\
.    if \nF \{\
.        de IX
.        tm Index:\\$1\t\\n%\t"\\$2"
..
.        if !\nF==2 \{\
.            nr % 0
.            nr F 2
.        \}
.    \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "EVP_MD-SHAKE 7ossl"
.TH EVP_MD-SHAKE 7ossl "2024-09-03" "3.3.2" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.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 an Extendable Output Function (\s-1XOF\s0), with a definition
similar to \s-1SHAKE,\s0 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).  Using the notation from \s-1NIST FIPS 202\s0
(Section 6.2), we have \s-1KECCAK\-KMAC\-128\s0(M,\ d) = KECCAK[256](M\ ||\ 00,\ d)
(see the description of \s-1KMAC128\s0 in Appendix A of \s-1NIST SP 800\-185\s0).
.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).  Using the notation from \s-1NIST FIPS 202\s0
(Section 6.2), we have \s-1KECCAK\-KMAC\-256\s0(M,\ d) = KECCAK[512](M\ ||\ 00,\ d)
(see the description of \s-1KMAC256\s0 in Appendix A of \s-1NIST SP 800\-185\s0).
.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.
.Sp
This parameter may be used when calling either \fBEVP_DigestFinal_ex()\fR or
\&\fBEVP_DigestFinal()\fR, since these functions were not designed to handle variable
length output. It is recommended to either use \fBEVP_DigestSqueeze()\fR or
\&\fBEVP_DigestFinalXOF()\fR instead.
.SH "NOTES"
.IX Header "NOTES"
For \s-1SHAKE\-128,\s0 to ensure the maximum security strength of 128 bits, the output
length passed to \fBEVP_DigestFinalXOF()\fR should be at least 32.
.PP
For \s-1SHAKE\-256,\s0 to ensure the maximum security strength of 256 bits, the output
length passed to \fBEVP_DigestFinalXOF()\fR should be 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\-2023 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>.