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 component inside krb5_checksum that
       is directly referable.

       The functions are used to create and verify checksums.  krb5_create_checksum() 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  implemented  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)