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.\" Copyright (c) 1999 Kungliga Tekniska Högskolan
.\" (Royal Institute of Technology, Stockholm, Sweden).
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" 3. Neither the name of the Institute nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $Id: krb5_create_checksum.3,v 1.6 2003/04/16 13:58:14 lha Exp $
.\"
.Dd April 7, 1999
.Dt NAME 3
.Os HEIMDAL
.Sh NAME
.Nm krb5_checksum_is_collision_proof ,
.Nm krb5_checksum_is_keyed ,
.Nm krb5_checksumsize ,
.Nm krb5_create_checksum ,
.Nm krb5_verify_checksum
.Nd creates and verifies checksums
.Sh LIBRARY
Kerberos 5 Library (libkrb5, -lkrb5)
.Sh SYNOPSIS
.In krb5.h
.Ft krb5_error_code
.Fn krb5_create_checksum "krb5_context context" "krb5_crypto crypto" "unsigned usage_or_type" "void *data" "size_t len" "Checksum *result"
.Ft krb5_error_code
.Fn krb5_verify_checksum "krb5_context context" "krb5_crypto crypto" "krb5_key_usage usage" "void *data" "size_t len" "Checksum *cksum"
.Ft krb5_boolean
.Fn krb5_checksum_is_collision_proof "krb5_context context" "krb5_cksumtype type"
.Ft krb5_boolean
.Fn krb5_checksum_is_keyed "krb5_context context" "krb5_cksumtype type"
.Sh DESCRIPTION
These functions are used to create and verify checksums.
.Fn krb5_create_checksum
creates a checksum of the specified data, and puts it in
.Fa result .
If
.Fa crypto
is
.Dv NULL ,
.Fa usage_or_type
specifies the checksum type to use; it must not be keyed. Otherwise
.Fa crypto
is an encryption context created by
.Fn krb5_crypto_init ,
and
.Fa usage_or_type
specifies a key-usage.
.Pp
.Fn krb5_verify_checksum
verifies the
.Fa checksum ,
against the provided data.
.Pp
.Fn krb5_checksum_is_collision_proof
returns true is the specified checksum is collision proof (that it's
very unlikely that two strings has the same hash value, and that it's
hard to find two strings that has the same hash). Examples of
collision proof checksums are MD5, and SHA1, while CRC32 is not.
.Pp
.Fn krb5_checksum_is_keyed
returns true if the specified checksum type is keyed (that the hash
value is a function of both the data, and a separate key). Examples of
keyed hash algorithms are HMAC-SHA1-DES3, and RSA-MD5-DES. The
.Dq plain
hash functions MD5, and SHA1 are not keyed.
.\" .Sh EXAMPLE
.\" .Sh BUGS
.Sh SEE ALSO
.Xr krb5_crypto_init 3 ,
.Xr krb5_encrypt 3
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