94 lines
2.7 KiB
Groff
94 lines
2.7 KiB
Groff
.\" $NetBSD: hmac.3,v 1.6 2018/05/23 02:08:40 christos Exp $
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.\"
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.\" Copyright (c) 2016 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Christos Zoulas.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\"TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd May 22, 2018
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.Dt HMAC 3
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.Os
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.Sh NAME
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.Nm hmac
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.Nd compute a key-Hash Message Authentication Code
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdlib.h
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.Ft ssize_t
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.Fn hmac "const char *hname" "const void *key" "size_t klen" "const void *text" "size_t tlen" "void *digest" "size_t dlen"
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.Sh DESCRIPTION
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The
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.Fn hmac
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function computes the key-Hash Message Authentication Code per
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.Tn RFC 2104
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and places the result in
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.Fa digest
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writing up to
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.Fa dlen
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bytes.
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The actual number of bytes that would be written is returned.
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.Pp
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The hash functions supported are: md2, md4, md5, rmd160, sha1, sha224,
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sha256, sha384, and sha512.
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.Sh RETURN VALUES
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The
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.Fn hmac
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function returns
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.Dv \-1
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if the
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.Fa hname
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is not found.
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Otherwise the actual length of the digest string is returned (which could
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be bigger or smaller than
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.Fa dlen ) .
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This length depends on the hashing function selected.
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.Sh SEE ALSO
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.Xr md2 3 ,
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.Xr md4 3 ,
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.Xr md5 3 ,
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.Xr openssl_HMAC 3 ,
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.Xr openssl_MD2 3 ,
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.Xr openssl_MD4 3 ,
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.Xr openssl_MD5 3 ,
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.Xr rmd160 3 ,
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.Xr sha1 3 ,
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.Xr sha2 3
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.Sh STANDARDS
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.Rs
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.%R RFC 2104
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.Re
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.Sh NOTES
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The maximum digest length has been extended from
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.Dv 64
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to
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.Dv 128
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bytes to handle SHA2.
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.Sh HISTORY
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The
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.Fn hmac
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function appeared in
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.Nx 8 .
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