1.\" Copyright (c) 1999 Kungliga Tekniska H�gskolan
2.\" $Id: krb5_create_checksum.3,v 1.4 2002/08/28 15:30:49 joda Exp $
3.Dd April 7, 1999
4.Dt NAME 3
5.Os HEIMDAL
6.Sh NAME
7.Nm krb5_checksum_is_collision_proof ,
8.Nm krb5_checksum_is_keyed ,
9.Nm krb5_checksumsize ,
10.Nm krb5_create_checksum ,
11.Nm krb5_verify_checksum
12.Nd creates and verifies checksums
13.Sh LIBRARY
14Kerberos 5 Library (libkrb5, -lkrb5)
15.Sh SYNOPSIS
16.Fd #include <krb5.h>
17.Ft krb5_error_code
18.Fn krb5_create_checksum "krb5_context context" "krb5_crypto crypto" "unsigned usage_or_type" "void *data" "size_t len" "Checksum *result"
19.Ft krb5_error_code
20.Fn krb5_verify_checksum "krb5_context context" "krb5_crypto crypto" "krb5_key_usage usage" "void *data" "size_t len" "Checksum *cksum"
21.Ft krb5_boolean
22.Fn krb5_checksum_is_collision_proof "krb5_context context" "krb5_cksumtype type"
23.Ft krb5_boolean
24.Fn krb5_checksum_is_keyed "krb5_context context" "krb5_cksumtype type"
25.Sh DESCRIPTION
26These functions are used to create and verify checksums.
27.Fn krb5_create_checksum
28creates a checksum of the specified data, and puts it in
29.Fa result .
30If
31.Fa crypto
32is
33.Dv NULL ,
34.Fa usage_or_type
35specifies the checksum type to use; it must not be keyed. Otherwise
36.Fa crypto
37is an encryption context created by
38.Fn krb5_crypto_init ,
39and
40.Fa usage_or_type
41specifies a key-usage.
42.Pp
43.Fn krb5_verify_checksum
44verifies the
45.Fa checksum ,
46against the provided data.
47.Pp
48.Fn krb5_checksum_is_collision_proof
49returns true is the specified checksum is collision proof (that it's
50very unlikely that two strings has the same hash value, and that it's
51hard to find two strings that has the same hash). Examples of
52collision proof checksums are MD5, and SHA1, while CRC32 is not.
53.Pp
54.Fn krb5_checksum_is_keyed
55returns true if the specified checksum type is keyed (that the hash
56value is a function of both the data, and a separate key). Examples of
57keyed hash algorithms are HMAC-SHA1-DES3, and RSA-MD5-DES. The
58.Dq plain
59hash functions MD5, and SHA1 are not keyed.
60.\" .Sh EXAMPLE
61.\" .Sh BUGS
62.Sh SEE ALSO
63.Xr krb5_crypto_init 3 ,
64.Xr krb5_encrypt 3
2.\" $Id: krb5_create_checksum.3,v 1.4 2002/08/28 15:30:49 joda Exp $
3.Dd April 7, 1999
4.Dt NAME 3
5.Os HEIMDAL
6.Sh NAME
7.Nm krb5_checksum_is_collision_proof ,
8.Nm krb5_checksum_is_keyed ,
9.Nm krb5_checksumsize ,
10.Nm krb5_create_checksum ,
11.Nm krb5_verify_checksum
12.Nd creates and verifies checksums
13.Sh LIBRARY
14Kerberos 5 Library (libkrb5, -lkrb5)
15.Sh SYNOPSIS
16.Fd #include <krb5.h>
17.Ft krb5_error_code
18.Fn krb5_create_checksum "krb5_context context" "krb5_crypto crypto" "unsigned usage_or_type" "void *data" "size_t len" "Checksum *result"
19.Ft krb5_error_code
20.Fn krb5_verify_checksum "krb5_context context" "krb5_crypto crypto" "krb5_key_usage usage" "void *data" "size_t len" "Checksum *cksum"
21.Ft krb5_boolean
22.Fn krb5_checksum_is_collision_proof "krb5_context context" "krb5_cksumtype type"
23.Ft krb5_boolean
24.Fn krb5_checksum_is_keyed "krb5_context context" "krb5_cksumtype type"
25.Sh DESCRIPTION
26These functions are used to create and verify checksums.
27.Fn krb5_create_checksum
28creates a checksum of the specified data, and puts it in
29.Fa result .
30If
31.Fa crypto
32is
33.Dv NULL ,
34.Fa usage_or_type
35specifies the checksum type to use; it must not be keyed. Otherwise
36.Fa crypto
37is an encryption context created by
38.Fn krb5_crypto_init ,
39and
40.Fa usage_or_type
41specifies a key-usage.
42.Pp
43.Fn krb5_verify_checksum
44verifies the
45.Fa checksum ,
46against the provided data.
47.Pp
48.Fn krb5_checksum_is_collision_proof
49returns true is the specified checksum is collision proof (that it's
50very unlikely that two strings has the same hash value, and that it's
51hard to find two strings that has the same hash). Examples of
52collision proof checksums are MD5, and SHA1, while CRC32 is not.
53.Pp
54.Fn krb5_checksum_is_keyed
55returns true if the specified checksum type is keyed (that the hash
56value is a function of both the data, and a separate key). Examples of
57keyed hash algorithms are HMAC-SHA1-DES3, and RSA-MD5-DES. The
58.Dq plain
59hash functions MD5, and SHA1 are not keyed.
60.\" .Sh EXAMPLE
61.\" .Sh BUGS
62.Sh SEE ALSO
63.Xr krb5_crypto_init 3 ,
64.Xr krb5_encrypt 3