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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* lib/crypto/raw/raw_aead.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 "raw.h"
#include "aead.h"
/* AEAD */
static krb5_error_code
krb5int_raw_crypto_length(const struct krb5_aead_provider *aead,
const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
krb5_cryptotype type,
unsigned int *length)
{
switch (type) {
case KRB5_CRYPTO_TYPE_PADDING:
*length = enc->block_size;
break;
default:
*length = 0;
break;
}
return 0;
}
static krb5_error_code
krb5int_raw_encrypt_iov(const struct krb5_aead_provider *aead,
const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
krb5_key key,
krb5_keyusage usage,
const krb5_data *ivec,
krb5_crypto_iov *data,
size_t num_data)
{
krb5_error_code ret;
krb5_crypto_iov *padding;
size_t i;
unsigned int blocksize = 0;
unsigned int plainlen = 0;
unsigned int padsize = 0;
ret = aead->crypto_length(aead, enc, hash, KRB5_CRYPTO_TYPE_PADDING, &blocksize);
if (ret != 0)
return ret;
for (i = 0; i < num_data; i++) {
krb5_crypto_iov *iov = &data[i];
if (iov->flags == KRB5_CRYPTO_TYPE_DATA)
plainlen += iov->data.length;
}
if (blocksize != 0) {
/* Check that the input data is correctly padded */
if (plainlen % blocksize)
padsize = blocksize - (plainlen % blocksize);
}
padding = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_PADDING);
if (padsize && (padding == NULL || padding->data.length < padsize))
return KRB5_BAD_MSIZE;
if (padding != NULL) {
memset(padding->data.data, 0, padsize);
padding->data.length = padsize;
}
assert(enc->encrypt_iov != NULL);
ret = enc->encrypt_iov(key, ivec, data, num_data); /* will update ivec */
return ret;
}
static krb5_error_code
krb5int_raw_decrypt_iov(const struct krb5_aead_provider *aead,
const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
krb5_key key,
krb5_keyusage usage,
const krb5_data *ivec,
krb5_crypto_iov *data,
size_t num_data)
{
krb5_error_code ret;
size_t i;
unsigned int blocksize = 0; /* careful, this is enc block size not confounder len */
unsigned int cipherlen = 0;
/* E(Confounder | Plaintext | Pad) | Checksum */
ret = aead->crypto_length(aead, enc, hash, KRB5_CRYPTO_TYPE_PADDING, &blocksize);
if (ret != 0)
return ret;
for (i = 0; i < num_data; i++) {
const krb5_crypto_iov *iov = &data[i];
if (ENCRYPT_DATA_IOV(iov))
cipherlen += iov->data.length;
}
if (blocksize == 0) {
/* Check for correct input length in CTS mode */
if (enc->block_size != 0 && cipherlen < enc->block_size)
return KRB5_BAD_MSIZE;
} else {
/* Check that the input data is correctly padded */
if ((cipherlen % blocksize) != 0)
return KRB5_BAD_MSIZE;
}
/* Validate header and trailer lengths */
/* derive the keys */
/* decrypt the plaintext (header | data | padding) */
assert(enc->decrypt_iov != NULL);
ret = enc->decrypt_iov(key, ivec, data, num_data); /* will update ivec */
return ret;
}
const struct krb5_aead_provider krb5int_aead_raw = {
krb5int_raw_crypto_length,
krb5int_raw_encrypt_iov,
krb5int_raw_decrypt_iov
};
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