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.\" Copyright (c) 1999 Kungliga Tekniska Högskolan
.\" $Id: krb5_create_checksum.3,v 1.2 2001/01/26 22:43:21 assar 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 SYNOPSIS
.Fd #include <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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