krb5/crypto/verify_checksum.c

	verify_checksum.c revision 505d05c73a6e56769f263d4803b22eddd168ee24
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * Copyright (C) 1998 by the FundsXpress, INC.
 *
 * All rights reserved.
 *
 * Export of this software from the United States of America may require
 * a specific license from the United States Government.  It is the
 * responsibility of any person or organization contemplating export to
 * obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of FundsXpress. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  FundsXpress makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <k5-int.h>
#include <cksumtypes.h>

krb5_error_code KRB5_CALLCONV
krb5_c_verify_checksum(krb5_context context, const krb5_keyblock *key,
            krb5_keyusage usage, const krb5_data *data,
            const krb5_checksum *cksum, krb5_boolean *valid)
{
    int i;
    size_t hashsize;
    krb5_error_code ret;
    krb5_data indata;
    krb5_checksum computed;

    for (i=0; i<krb5_cksumtypes_length; i++) {
    if (krb5_cksumtypes_list[i].ctype == cksum->checksum_type)
        break;
    }

    if (i == krb5_cksumtypes_length)
    return(KRB5_BAD_ENCTYPE);

    /* if there's actually a verify function, call it */

    indata.length = cksum->length;
    indata.data = (char *) cksum->contents;
    *valid = 0;

    if (krb5_cksumtypes_list[i].keyhash &&
    krb5_cksumtypes_list[i].keyhash->verify)
    return((*(krb5_cksumtypes_list[i].keyhash->verify))(
        context, key, usage, 0, data, &indata, valid));

    /* otherwise, make the checksum again, and compare */

    if ((ret = krb5_c_checksum_length(context, cksum->checksum_type, &hashsize)))
    return(ret);

    if (cksum->length != hashsize)
    return(KRB5_BAD_MSIZE);

    computed.length = hashsize;

    if ((ret = krb5_c_make_checksum(context, cksum->checksum_type, key, usage,
                   data, &computed))) {
    FREE(computed.contents, computed.length);
    return(ret);
    }

    *valid = (memcmp(computed.contents, cksum->contents, hashsize) == 0);

    FREE(computed.contents, computed.length);

    return(0);
}