1/*
2 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
3 * Use is subject to license terms.
4 */
5
6
7/*
8 * lib/crypto/aes/aes_s2k.c
9 *
10 * Copyright 2003 by the Massachusetts Institute of Technology.
11 * All Rights Reserved.
12 *
13 * Export of this software from the United States of America may
14 *   require a specific license from the United States Government.
15 *   It is the responsibility of any person or organization contemplating
16 *   export to obtain such a license before exporting.
17 *
18 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
19 * distribute this software and its documentation for any purpose and
20 * without fee is hereby granted, provided that the above copyright
21 * notice appear in all copies and that both that copyright notice and
22 * this permission notice appear in supporting documentation, and that
23 * the name of M.I.T. not be used in advertising or publicity pertaining
24 * to distribution of the software without specific, written prior
25 * permission.  Furthermore if you modify this software you must label
26 * your software as modified software and not distribute it in such a
27 * fashion that it might be confused with the original M.I.T. software.
28 * M.I.T. makes no representations about the suitability of
29 * this software for any purpose.  It is provided "as is" without express
30 * or implied warranty.
31 *
32 *
33 * krb5int_aes_string_to_key
34 */
35
36#include "k5-int.h"
37#include "dk.h"
38#include "aes_s2k.h"
39
40#define DEFAULT_ITERATION_COUNT		4096 /* was 0xb000L in earlier drafts */
41#define MAX_ITERATION_COUNT		0x1000000L
42
43krb5_error_code
44krb5int_aes_string_to_key(krb5_context context,
45			  const struct krb5_enc_provider *enc,
46			  const krb5_data *string,
47			  const krb5_data *salt,
48			  const krb5_data *params,
49			  krb5_keyblock *key)
50{
51    unsigned long iter_count;
52    krb5_data out;
53    static const krb5_data usage = { KV5M_DATA, 8, "kerberos" };
54    krb5_error_code err;
55    /* Solaris Kerberos */
56    krb5_keyblock *inkey = NULL;
57
58    if (params) {
59	unsigned char *p = (unsigned char *) params->data;
60	if (params->length != 4)
61	    return KRB5_ERR_BAD_S2K_PARAMS;
62	/* The first two need casts in case 'int' is 16 bits.  */
63	iter_count = (((unsigned long)p[0] << 24)
64		      | ((unsigned long)p[1] << 16)
65		      | (p[2] <<  8)
66		      | (p[3]));
67	if (iter_count == 0) {
68	/*
69	    iter_count = (1L << 16) << 16;
70	    if (((iter_count >> 16) >> 16) != 1)
71		return KRB5_ERR_BAD_S2K_PARAMS;
72	*/
73	    iter_count = DEFAULT_ITERATION_COUNT;
74	}
75    } else
76	iter_count = DEFAULT_ITERATION_COUNT;
77
78    /* This is not a protocol specification constraint; this is an
79       implementation limit, which should eventually be controlled by
80       a config file.  */
81    if (iter_count >= MAX_ITERATION_COUNT)
82	return KRB5_ERR_BAD_S2K_PARAMS;
83
84    /*
85     * Dense key space, no parity bits or anything, so take a shortcut
86     * and use the key contents buffer for the generated bytes.
87     */
88    /* Solaris Kerberos */
89    if (key->length != 16 && key->length != 32)
90	return KRB5_CRYPTO_INTERNAL;
91    out.data = (char *) key->contents;
92    out.length = key->length;
93    /* Solaris Kerberos */
94    err = krb5int_pbkdf2_hmac_sha1 (context, &out, iter_count, key->enctype,
95		string, salt);
96    if (err) {
97	memset(out.data, 0, out.length);
98	return err;
99    }
100
101    /*
102     * Solaris Kerberos:
103     * The derive key operation below will not work correctly
104     * if the input and output key pointers are to the same
105     * data.  This is because the key object handle (PKCS#11)
106     * gets out-of-sync with the original key when the contents
107     * are modified.  We copy the original key here for use
108     * below in the derive_key step, then we free this key
109     * before exiting.
110     */
111    err  = krb5_copy_keyblock(context, key, &inkey);
112    if (err) {
113	memset(out.data, 0, out.length);
114	return err;
115    }
116
117    err = krb5_derive_key (context, enc, inkey, key, &usage);
118    if (err) {
119	memset(out.data, 0, out.length);
120    }
121    krb5_free_keyblock(context, inkey);
122
123    return (err);
124}
125