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/*
* lib/crypto/aes/aes_s2k.c
*
* Copyright 2003 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.
*
*
* krb5int_aes_string_to_key
*/
#include "k5-int.h"
#include "dk.h"
#include "aes_s2k.h"
#define DEFAULT_ITERATION_COUNT 4096 /* was 0xb000L in earlier drafts */
#define MAX_ITERATION_COUNT 0x1000000L
krb5_error_code
krb5int_aes_string_to_key(const struct krb5_enc_provider *enc,
const krb5_data *string,
const krb5_data *salt,
const krb5_data *params,
krb5_keyblock *key)
{
unsigned long iter_count;
krb5_data out;
static const krb5_data usage = { KV5M_DATA, 8, "kerberos" };
krb5_key tempkey = NULL;
krb5_error_code err;
if (params) {
unsigned char *p = (unsigned char *) params->data;
if (params->length != 4)
return KRB5_ERR_BAD_S2K_PARAMS;
/* The first two need casts in case 'int' is 16 bits. */
iter_count = load_32_be(p);
if (iter_count == 0) {
iter_count = (1UL << 16) << 16;
if (((iter_count >> 16) >> 16) != 1)
return KRB5_ERR_BAD_S2K_PARAMS;
}
} else
iter_count = DEFAULT_ITERATION_COUNT;
/* This is not a protocol specification constraint; this is an
implementation limit, which should eventually be controlled by
a config file. */
if (iter_count >= MAX_ITERATION_COUNT)
return KRB5_ERR_BAD_S2K_PARAMS;
/* Use the output keyblock contents for temporary space. */
out.data = (char *) key->contents;
out.length = key->length;
if (out.length != 16 && out.length != 32)
return KRB5_CRYPTO_INTERNAL;
err = krb5int_pbkdf2_hmac_sha1 (&out, iter_count, string, salt);
if (err)
goto cleanup;
err = krb5_k_create_key (NULL, key, &tempkey);
if (err)
goto cleanup;
err = krb5int_derive_keyblock (enc, tempkey, key, &usage);
cleanup:
if (err)
memset (out.data, 0, out.length);
krb5_k_free_key (NULL, tempkey);
return err;
}
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