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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/kdb/decrypt_key.c */
/*
* Copyright 1990,1991,2023 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.
*/
/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* 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 FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include "k5-int.h"
#include "kdb.h"
/* Decrypt key_data, putting the result into dbkey_out and (if not null)
* keysalt_out. */
krb5_error_code
krb5_dbe_def_decrypt_key_data(krb5_context context, const krb5_keyblock *mkey,
const krb5_key_data *kd,
krb5_keyblock *dbkey_out,
krb5_keysalt *keysalt_out)
{
krb5_error_code ret;
int16_t keylen;
krb5_enc_data cipher;
krb5_data plain = empty_data();
krb5_keyblock kb = { 0 };
krb5_keysalt salt = { 0 };
memset(dbkey_out, 0, sizeof(*dbkey_out));
if (keysalt_out != NULL)
memset(keysalt_out, 0, sizeof(*keysalt_out));
if (mkey == NULL)
return KRB5_KDB_BADSTORED_MKEY;
if (kd->key_data_contents[0] != NULL && kd->key_data_length[0] >= 2) {
keylen = load_16_le(kd->key_data_contents[0]);
if (keylen < 0)
return EINVAL;
cipher.enctype = ENCTYPE_UNKNOWN;
cipher.ciphertext = make_data(kd->key_data_contents[0] + 2,
kd->key_data_length[0] - 2);
ret = alloc_data(&plain, kd->key_data_length[0] - 2);
if (ret)
goto cleanup;
ret = krb5_c_decrypt(context, mkey, 0, 0, &cipher, &plain);
if (ret)
goto cleanup;
/* Make sure the plaintext has at least as many bytes as the true ke
* length (it may have more due to padding). */
if ((unsigned int)keylen > plain.length) {
ret = KRB5_CRYPTO_INTERNAL;
if (ret)
goto cleanup;
}
kb.magic = KV5M_KEYBLOCK;
kb.enctype = kd->key_data_type[0];
kb.length = keylen;
kb.contents = (uint8_t *)plain.data;
plain = empty_data();
}
/* Decode salt data. */
if (keysalt_out != NULL) {
if (kd->key_data_ver == 2) {
salt.type = kd->key_data_type[1];
salt.data.length = kd->key_data_length[1];
if (kd->key_data_length[1] > 0) {
ret = alloc_data(&salt.data, kd->key_data_length[1]);
if (ret)
goto cleanup;
memcpy(salt.data.data, kd->key_data_contents[1],
salt.data.length);
}
} else {
salt.type = KRB5_KDB_SALTTYPE_NORMAL;
}
}
*dbkey_out = kb;
if (keysalt_out != NULL)
*keysalt_out = salt;
memset(&kb, 0, sizeof(kb));
memset(&salt, 0, sizeof(salt));
cleanup:
zapfree(plain.data, plain.length);
krb5_free_keyblock_contents(context, &kb);
free(salt.data.data);
return ret;
}
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