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NAME(3) 		     Library Functions Manual			 NAME(3)

NAME
     krb5_checksum,   krb5_checksum_disable,   krb5_checksum_is_collision_proof,
     krb5_checksum_is_keyed,	  krb5_checksumsize,	   krb5_cksumtype_valid,
     krb5_copy_checksum,   krb5_create_checksum,   krb5_crypto_get_checksum_type
     krb5_free_checksum,	 krb5_free_checksum_contents,	      krb5_hmac,
     krb5_verify_checksum -- creates, handles and verifies checksums

LIBRARY
     Kerberos 5 Library (libkrb5, -lkrb5)

SYNOPSIS
     #include <krb5.h>

     typedef Checksum krb5_checksum;

     void
     krb5_checksum_disable(krb5_context context, krb5_cksumtype type);

     krb5_boolean
     krb5_checksum_is_collision_proof(krb5_context context,
	 krb5_cksumtype type);

     krb5_boolean
     krb5_checksum_is_keyed(krb5_context context, krb5_cksumtype type);

     krb5_error_code
     krb5_cksumtype_valid(krb5_context context, krb5_cksumtype ctype);

     krb5_error_code
     krb5_checksumsize(krb5_context context, krb5_cksumtype type, size_t *size);

     krb5_error_code
     krb5_create_checksum(krb5_context context, krb5_crypto crypto,
	 krb5_key_usage usage, int type, void *data, size_t len,
	 Checksum *result);

     krb5_error_code
     krb5_verify_checksum(krb5_context context, krb5_crypto crypto,
	 krb5_key_usage usage, void *data, size_t len, Checksum *cksum);

     krb5_error_code
     krb5_crypto_get_checksum_type(krb5_context context, krb5_crypto crypto,
	 krb5_cksumtype *type);

     void
     krb5_free_checksum(krb5_context context, krb5_checksum *cksum);

     void
     krb5_free_checksum_contents(krb5_context context, krb5_checksum *cksum);

     krb5_error_code
     krb5_hmac(krb5_context context, krb5_cksumtype cktype, const void *data,
	 size_t len, unsigned usage, krb5_keyblock *key, Checksum *result);

     krb5_error_code
     krb5_copy_checksum(krb5_context context, const krb5_checksum *old,
	 krb5_checksum **new);

DESCRIPTION
     The  krb5_checksum structure holds a Kerberos checksum.  There is no compo-
     nent inside krb5_checksum that is directly referable.

     The functions are used to create and verify checksums.   krb5_create_check-
     sum()  creates a checksum of the specified data, and puts it in result.  If
     crypto is NULL, usage_or_type specifies the checksum type to use;	it  must
     not  be  keyed.  Otherwise  crypto  is  an  encryption  context  created by
     krb5_crypto_init(), and usage_or_type specifies a key-usage.

     krb5_verify_checksum() verifies the checksum against the provided data.

     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.

     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 "plain" hash functions MD5, and SHA1 are not keyed.

     krb5_crypto_get_checksum_type() returns the checksum type that will be used
     when creating a checksum for the given crypto context.   This  function  is
     useful  in  combination  with krb5_checksumsize() when you want to know the
     size a checksum will use when you create it.

     krb5_cksumtype_valid() returns 0 or an error if the checksumtype is  imple-
     mented and not currently disabled in this kerberos library.

     krb5_checksumsize() returns the size of the outdata of checksum function.

     krb5_copy_checksum()  returns  a  copy of the checksum krb5_free_checksum()
     should use used to free the new checksum.

     krb5_free_checksum() free the checksum and the content of the checksum.

     krb5_free_checksum_contents() frees the content of checksum in cksum.

     krb5_hmac() calculates the HMAC over  data  (with	length	len)  using  the
     keyusage  usage and keyblock key.	Note that keyusage is not always used in
     checksums.

     krb5_checksum_disable globally disables the checksum type.

SEE ALSO
     krb5_crypto_init(3), krb5_c_encrypt(3), krb5_encrypt(3)

HEIMDAL 			 August 12, 2005			 NAME(3)

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