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/*
* lib/crypto/verify_checksum_iov.c
*
* Copyright 2008 by the Massachusetts Institute of Technology.
* 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 M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
#include "k5-int.h"
#include "cksumtypes.h"
#include "aead.h"
krb5_error_code KRB5_CALLCONV
krb5_c_verify_checksum_iov(krb5_context context,
krb5_cksumtype checksum_type,
const krb5_keyblock *key,
krb5_keyusage usage,
const krb5_crypto_iov *data,
size_t num_data,
krb5_boolean *valid)
{
unsigned int i;
size_t cksumlen;
krb5_error_code ret;
krb5_data computed;
krb5_crypto_iov *checksum;
for (i = 0; i < krb5_cksumtypes_length; i++) {
if (krb5_cksumtypes_list[i].ctype == checksum_type)
break;
}
if (i == krb5_cksumtypes_length)
return(KRB5_BAD_ENCTYPE);
checksum = krb5int_c_locate_iov((krb5_crypto_iov *)data, num_data, KRB5_CRYPTO_TYPE_CHECKSUM);
if (checksum == NULL)
return(KRB5_BAD_MSIZE);
/* if there's actually a verify function, call it */
if (krb5_cksumtypes_list[i].keyhash &&
krb5_cksumtypes_list[i].keyhash->verify_iov)
return((*(krb5_cksumtypes_list[i].keyhash->verify_iov))(key, usage, 0,
data, num_data,
&checksum->data,
valid));
/* otherwise, make the checksum again, and compare */
if (krb5_cksumtypes_list[i].keyhash != NULL)
computed.length = krb5_cksumtypes_list[i].keyhash->hashsize;
else
computed.length = krb5_cksumtypes_list[i].hash->hashsize;
if (krb5_cksumtypes_list[i].trunc_size != 0)
cksumlen = krb5_cksumtypes_list[i].trunc_size;
else
cksumlen = computed.length;
if (checksum->data.length != cksumlen)
return(KRB5_BAD_MSIZE);
computed.data = malloc(computed.length);
if (computed.data == NULL)
return(ENOMEM);
if ((ret = krb5int_c_make_checksum_iov(&krb5_cksumtypes_list[i], key, usage,
data, num_data, &computed))) {
free(computed.data);
return(ret);
}
*valid = (computed.length == cksumlen) &&
(memcmp(computed.data, checksum->data.data, cksumlen) == 0);
free(computed.data);
return(0);
}
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