Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
NetBSD/lib/libcrypto/man/openssl_hmac.3

244 lines
7.8 KiB
Groff
Raw Blame History

.\" $NetBSD: openssl_hmac.3,v 1.9 2004/03/20 21:48:47 groo Exp $
.\"
.\" Automatically generated by Pod::Man version 1.15
.\" Sat Mar 20 16:41:14 2004
.\"
.\" Standard preamble:
.\" ======================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Ip \" List item
.br
.ie \\n(.$>=3 .ne \\$3
.el .ne 3
.IP "\\$1" \\$2
..
.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. | will give a
.\" real vertical bar. \*(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-|\(bv\*(Tr
.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" ''
'br\}
.\"
.\" If the F register is turned on, we'll generate index entries on stderr
.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and
.\" index entries marked with X<> in POD. Of course, you'll have to process
.\" the output yourself in some meaningful fashion.
.if \nF \{\
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. nr % 0
. rr F
.\}
.\"
.\" For nroff, turn off justification. Always turn off hyphenation; it
.\" makes way too many mistakes in technical documents.
.hy 0
.if n .na
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear. Run. Save yourself. No user-serviceable parts.
.bd B 3
. \" 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 "hmac 3"
.TH hmac 3 "0.9.7d" "2003-09-24" "OpenSSL"
.UC
.SH "NAME"
\&\s-1HMAC\s0, HMAC_Init, HMAC_Update, HMAC_Final, HMAC_cleanup \- \s-1HMAC\s0 message
authentication code
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/hmac.h>
.Ve
.Vb 3
\& unsigned char *HMAC(const EVP_MD *evp_md, const void *key,
\& int key_len, const unsigned char *d, int n,
\& unsigned char *md, unsigned int *md_len);
.Ve
.Vb 1
\& void HMAC_CTX_init(HMAC_CTX *ctx);
.Ve
.Vb 6
\& void HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len,
\& const EVP_MD *md);
\& void HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int key_len,
\& const EVP_MD *md);
\& void HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, int len);
\& void HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len);
.Ve
.Vb 2
\& void HMAC_CTX_cleanup(HMAC_CTX *ctx);
\& void HMAC_cleanup(HMAC_CTX *ctx);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\s-1HMAC\s0 is a \s-1MAC\s0 (message authentication code), i.e. a keyed hash
function used for message authentication, which is based on a hash
function.
.PP
\&\fIHMAC()\fR computes the message authentication code of the \fBn\fR bytes at
\&\fBd\fR using the hash function \fBevp_md\fR and the key \fBkey\fR which is
\&\fBkey_len\fR bytes long.
.PP
It places the result in \fBmd\fR (which must have space for the output of
the hash function, which is no more than \fB\s-1EVP_MAX_MD_SIZE\s0\fR bytes).
If \fBmd\fR is \s-1NULL\s0, the digest is placed in a static array. The size of
the output is placed in \fBmd_len\fR, unless it is \fB\s-1NULL\s0\fR.
.PP
\&\fBevp_md\fR can be \fIEVP_sha1()\fR, \fIEVP_ripemd160()\fR etc.
\&\fBkey\fR and \fBevp_md\fR may be \fB\s-1NULL\s0\fR if a key and hash function have
been set in a previous call to \fIHMAC_Init()\fR for that \fB\s-1HMAC_CTX\s0\fR.
.PP
\&\fIHMAC_CTX_init()\fR initialises a \fB\s-1HMAC_CTX\s0\fR before first use. It must be
called.
.PP
\&\fIHMAC_CTX_cleanup()\fR erases the key and other data from the \fB\s-1HMAC_CTX\s0\fR
and releases any associated resources. It must be called when an
\&\fB\s-1HMAC_CTX\s0\fR is no longer required.
.PP
\&\fIHMAC_cleanup()\fR is an alias for \fIHMAC_CTX_cleanup()\fR included for back
compatibility with 0.9.6b, it is deprecated.
.PP
The following functions may be used if the message is not completely
stored in memory:
.PP
\&\fIHMAC_Init()\fR initializes a \fB\s-1HMAC_CTX\s0\fR structure to use the hash
function \fBevp_md\fR and the key \fBkey\fR which is \fBkey_len\fR bytes
long. It is deprecated and only included for backward compatibility
with OpenSSL 0.9.6b.
.PP
\&\fIHMAC_Init_ex()\fR initializes or reuses a \fB\s-1HMAC_CTX\s0\fR structure to use
the function \fBevp_md\fR and key \fBkey\fR. Either can be \s-1NULL\s0, in which
case the existing one will be reused. \fIHMAC_CTX_init()\fR must have been
called before the first use of an \fB\s-1HMAC_CTX\s0\fR in this
function. \fBN.B. \f(BIHMAC_Init()\fB had this undocumented behaviour in
previous versions of OpenSSL \- failure to switch to \f(BIHMAC_Init_ex()\fB in
programs that expect it will cause them to stop working\fR.
.PP
\&\fIHMAC_Update()\fR can be called repeatedly with chunks of the message to
be authenticated (\fBlen\fR bytes at \fBdata\fR).
.PP
\&\fIHMAC_Final()\fR places the message authentication code in \fBmd\fR, which
must have space for the hash function output.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIHMAC()\fR returns a pointer to the message authentication code.
.PP
\&\fIHMAC_CTX_init()\fR, \fIHMAC_Init_ex()\fR, \fIHMAC_Update()\fR, \fIHMAC_Final()\fR and
\&\fIHMAC_CTX_cleanup()\fR do not return values.
.SH "CONFORMING TO"
.IX Header "CONFORMING TO"
\&\s-1RFC\s0 2104
.SH "SEE ALSO"
.IX Header "SEE ALSO"
openssl_sha(3), openssl_evp(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fIHMAC()\fR, \fIHMAC_Init()\fR, \fIHMAC_Update()\fR, \fIHMAC_Final()\fR and \fIHMAC_cleanup()\fR
are available since SSLeay 0.9.0.
.PP
\&\fIHMAC_CTX_init()\fR, \fIHMAC_Init_ex()\fR and \fIHMAC_CTX_cleanup()\fR are available
since OpenSSL 0.9.7.
Reference in New Issue View Git Blame Copy Permalink