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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/crypto/krb/enc_old.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 "crypto_int.h"
unsigned int
krb5int_old_crypto_length(const struct krb5_keytypes *ktp,
krb5_cryptotype type)
{
switch (type) {
case KRB5_CRYPTO_TYPE_HEADER:
return ktp->enc->block_size + ktp->hash->hashsize;
case KRB5_CRYPTO_TYPE_PADDING:
return ktp->enc->block_size;
case KRB5_CRYPTO_TYPE_TRAILER:
return 0;
case KRB5_CRYPTO_TYPE_CHECKSUM:
return ktp->hash->hashsize;
default:
assert(0 && "invalid cryptotype passed to krb5int_old_crypto_length");
return 0;
}
}
krb5_error_code
krb5int_old_encrypt(const struct krb5_keytypes *ktp, krb5_key key,
krb5_keyusage usage, const krb5_data *ivec,
krb5_crypto_iov *data, size_t num_data)
{
const struct krb5_enc_provider *enc = ktp->enc;
const struct krb5_hash_provider *hash = ktp->hash;
krb5_error_code ret;
krb5_crypto_iov *header, *trailer, *padding;
krb5_data checksum, confounder, crcivec = empty_data();
unsigned int plainlen, padsize;
size_t i;
/* E(Confounder | Checksum | Plaintext | Pad) */
plainlen = enc->block_size + hash->hashsize;
for (i = 0; i < num_data; i++) {
krb5_crypto_iov *iov = &data[i];
if (iov->flags == KRB5_CRYPTO_TYPE_DATA)
plainlen += iov->data.length;
}
header = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_HEADER);
if (header == NULL ||
header->data.length < enc->block_size + hash->hashsize)
return KRB5_BAD_MSIZE;
/* Trailer may be absent. */
trailer = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_TRAILER);
if (trailer != NULL)
trailer->data.length = 0;
/* Check that the input data is correctly padded. */
padsize = krb5_roundup(plainlen, enc->block_size) - plainlen;
padding = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_PADDING);
if (padsize > 0 && (padding == NULL || padding->data.length < padsize))
return KRB5_BAD_MSIZE;
if (padding) {
padding->data.length = padsize;
memset(padding->data.data, 0, padsize);
}
/* Generate a confounder in the header block. */
confounder = make_data(header->data.data, enc->block_size);
ret = krb5_c_random_make_octets(0, &confounder);
if (ret != 0)
goto cleanup;
checksum = make_data(header->data.data + enc->block_size, hash->hashsize);
memset(checksum.data, 0, hash->hashsize);
/* Checksum the plaintext with zeroed checksum and padding. */
ret = hash->hash(data, num_data, &checksum);
if (ret != 0)
goto cleanup;
/* Use the key as the ivec for des-cbc-crc if none was provided. */
if (key->keyblock.enctype == ENCTYPE_DES_CBC_CRC && ivec == NULL) {
ret = alloc_data(&crcivec, key->keyblock.length);
memcpy(crcivec.data, key->keyblock.contents, key->keyblock.length);
ivec = &crcivec;
}
ret = enc->encrypt(key, ivec, data, num_data);
if (ret != 0)
goto cleanup;
cleanup:
zapfree(crcivec.data, crcivec.length);
return ret;
}
krb5_error_code
krb5int_old_decrypt(const struct krb5_keytypes *ktp, krb5_key key,
krb5_keyusage usage, const krb5_data *ivec,
krb5_crypto_iov *data, size_t num_data)
{
const struct krb5_enc_provider *enc = ktp->enc;
const struct krb5_hash_provider *hash = ktp->hash;
krb5_error_code ret;
krb5_crypto_iov *header, *trailer;
krb5_data checksum, crcivec = empty_data();
char *saved_checksum = NULL;
size_t i;
unsigned int cipherlen = 0;
/* Check that the input data is correctly padded. */
for (i = 0; i < num_data; i++) {
const krb5_crypto_iov *iov = &data[i];
if (ENCRYPT_IOV(iov))
cipherlen += iov->data.length;
}
if (cipherlen % enc->block_size != 0)
return KRB5_BAD_MSIZE;
header = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_HEADER);
if (header == NULL ||
header->data.length != enc->block_size + hash->hashsize)
return KRB5_BAD_MSIZE;
trailer = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_TRAILER);
if (trailer != NULL && trailer->data.length != 0)
return KRB5_BAD_MSIZE;
/* Use the key as the ivec for des-cbc-crc if none was provided. */
if (key->keyblock.enctype == ENCTYPE_DES_CBC_CRC && ivec == NULL) {
ret = alloc_data(&crcivec, key->keyblock.length);
memcpy(crcivec.data, key->keyblock.contents, key->keyblock.length);
ivec = &crcivec;
}
/* Decrypt the ciphertext. */
ret = enc->decrypt(key, ivec, data, num_data);
if (ret != 0)
goto cleanup;
/* Save the checksum, then zero it out in the plaintext. */
checksum = make_data(header->data.data + enc->block_size, hash->hashsize);
saved_checksum = k5alloc(hash->hashsize, &ret);
if (saved_checksum == NULL)
goto cleanup;
memcpy(saved_checksum, checksum.data, checksum.length);
memset(checksum.data, 0, checksum.length);
/*
* Checksum the plaintext (with zeroed checksum field), storing the result
* back into the plaintext field we just zeroed out. Then compare it to
* the saved checksum.
*/
ret = hash->hash(data, num_data, &checksum);
if (memcmp(checksum.data, saved_checksum, checksum.length) != 0) {
ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
goto cleanup;
}
cleanup:
zapfree(crcivec.data, crcivec.length);
zapfree(saved_checksum, hash->hashsize);
return ret;
}
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