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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;
const struct krb5_cksumtypes *ctp;
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;
ctp = &krb5_cksumtypes_list[i];
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 (ctp->keyhash && ctp->keyhash->verify_iov) {
return (*ctp->keyhash->verify_iov)(key, usage, 0, data, num_data,
&checksum->data, valid);
}
/* Otherwise, make the checksum again, and compare. */
if (ctp->keyhash != NULL)
computed.length = ctp->keyhash->hashsize;
else
computed.length = ctp->hash->hashsize;
if (ctp->trunc_size != 0)
cksumlen = ctp->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;
ret = krb5int_c_make_checksum_iov(&krb5_cksumtypes_list[i], key, usage,
data, num_data, &computed);
if (ret) {
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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