#include "k5-int.h"
#include "old.h"
krb5_error_code
krb5_old_decrypt(const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
const krb5_keyblock *key,
krb5_keyusage usage,
const krb5_data *ivec,
const krb5_data *input,
krb5_data *arg_output)
{
krb5_error_code ret;
size_t blocksize, hashsize, plainsize;
unsigned char *cksumdata, *cn;
krb5_data output, cksum, crcivec;
int alloced;
blocksize = enc->block_size;
hashsize = hash->hashsize;
plainsize = input->length - blocksize - hashsize;
if (arg_output->length < plainsize)
return(KRB5_BAD_MSIZE);
if ((cksumdata = (unsigned char *) malloc(hashsize)) == NULL)
return(ENOMEM);
if (arg_output->length < input->length) {
output.length = input->length;
if ((output.data = (char *) malloc(output.length)) == NULL) {
free(cksumdata);
return(ENOMEM);
}
alloced = 1;
} else {
output.length = input->length;
output.data = arg_output->data;
alloced = 0;
}
if (ivec != NULL && ivec->length == blocksize) {
cn = malloc(blocksize);
if (cn == NULL) {
ret = ENOMEM;
goto cleanup;
}
memcpy(cn, input->data + input->length - blocksize, blocksize);
} else
cn = NULL;
if ((key->enctype == ENCTYPE_DES_CBC_CRC) && (ivec == 0)) {
crcivec.length = key->length;
crcivec.data = (char *) key->contents;
ivec = &crcivec;
}
if ((ret = ((*(enc->decrypt))(key, ivec, input, &output))))
goto cleanup;
memcpy(cksumdata, output.data+blocksize, hashsize);
memset(output.data+blocksize, 0, hashsize);
cksum.length = hashsize;
cksum.data = output.data+blocksize;
if ((ret = ((*(hash->hash))(1, &output, &cksum))))
goto cleanup;
if (memcmp(cksum.data, cksumdata, cksum.length) != 0) {
ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
goto cleanup;
}
if (alloced) {
memcpy(arg_output->data, output.data+blocksize+hashsize,
plainsize);
} else {
memmove(arg_output->data, arg_output->data+blocksize+hashsize,
plainsize);
}
arg_output->length = plainsize;
if (cn != NULL)
memcpy(ivec->data, cn, blocksize);
ret = 0;
cleanup:
if (alloced) {
memset(output.data, 0, output.length);
free(output.data);
}
if (cn != NULL)
free(cn);
memset(cksumdata, 0, hashsize);
free(cksumdata);
return(ret);
}