aboutsummaryrefslogtreecommitdiffstats
path: root/src/tls/pkcs5.c
blob: 9b8e4256509a7dc914824e199c1cae4f41d2b674 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
/*
 * PKCS #5 (Password-based Encryption)
 * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "crypto.h"
#include "md5.h"
#include "asn1.h"
#include "pkcs5.h"


struct pkcs5_params {
	enum pkcs5_alg {
		PKCS5_ALG_UNKNOWN,
		PKCS5_ALG_MD5_DES_CBC
	} alg;
	u8 salt[8];
	size_t salt_len;
	unsigned int iter_count;
};


enum pkcs5_alg pkcs5_get_alg(struct asn1_oid *oid)
{
	if (oid->len == 7 &&
	    oid->oid[0] == 1 /* iso */ &&
	    oid->oid[1] == 2 /* member-body */ &&
	    oid->oid[2] == 840 /* us */ &&
	    oid->oid[3] == 113549 /* rsadsi */ &&
	    oid->oid[4] == 1 /* pkcs */ &&
	    oid->oid[5] == 5 /* pkcs-5 */ &&
	    oid->oid[6] == 3 /* pbeWithMD5AndDES-CBC */)
		return PKCS5_ALG_MD5_DES_CBC;

	return PKCS5_ALG_UNKNOWN;
}


static int pkcs5_get_params(const u8 *enc_alg, size_t enc_alg_len,
			    struct pkcs5_params *params)
{
	struct asn1_hdr hdr;
	const u8 *enc_alg_end, *pos, *end;
	struct asn1_oid oid;
	char obuf[80];

	/* AlgorithmIdentifier */

	enc_alg_end = enc_alg + enc_alg_len;

	os_memset(params, 0, sizeof(*params));

	if (asn1_get_oid(enc_alg, enc_alg_end - enc_alg, &oid, &pos)) {
		wpa_printf(MSG_DEBUG, "PKCS #5: Failed to parse OID "
			   "(algorithm)");
		return -1;
	}

	asn1_oid_to_str(&oid, obuf, sizeof(obuf));
	wpa_printf(MSG_DEBUG, "PKCS #5: encryption algorithm %s", obuf);
	params->alg = pkcs5_get_alg(&oid);
	if (params->alg == PKCS5_ALG_UNKNOWN) {
		wpa_printf(MSG_INFO, "PKCS #5: unsupported encryption "
			   "algorithm %s", obuf);
		return -1;
	}

	/*
	 * PKCS#5, Section 8
	 * PBEParameter ::= SEQUENCE {
	 *   salt OCTET STRING SIZE(8),
	 *   iterationCount INTEGER }
	 */

	if (asn1_get_next(pos, enc_alg_end - pos, &hdr) < 0 ||
	    hdr.class != ASN1_CLASS_UNIVERSAL ||
	    hdr.tag != ASN1_TAG_SEQUENCE) {
		wpa_printf(MSG_DEBUG, "PKCS #5: Expected SEQUENCE "
			   "(PBEParameter) - found class %d tag 0x%x",
			   hdr.class, hdr.tag);
		return -1;
	}
	pos = hdr.payload;
	end = hdr.payload + hdr.length;

	/* salt OCTET STRING SIZE(8) */
	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
	    hdr.class != ASN1_CLASS_UNIVERSAL ||
	    hdr.tag != ASN1_TAG_OCTETSTRING ||
	    hdr.length != 8) {
		wpa_printf(MSG_DEBUG, "PKCS #5: Expected OCTETSTRING SIZE(8) "
			   "(salt) - found class %d tag 0x%x size %d",
			   hdr.class, hdr.tag, hdr.length);
		return -1;
	}
	pos = hdr.payload + hdr.length;
	os_memcpy(params->salt, hdr.payload, hdr.length);
	params->salt_len = hdr.length;
	wpa_hexdump(MSG_DEBUG, "PKCS #5: salt",
		    params->salt, params->salt_len);

	/* iterationCount INTEGER */
	if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
	    hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_INTEGER) {
		wpa_printf(MSG_DEBUG, "PKCS #5: Expected INTEGER - found "
			   "class %d tag 0x%x", hdr.class, hdr.tag);
		return -1;
	}
	if (hdr.length == 1)
		params->iter_count = *hdr.payload;
	else if (hdr.length == 2)
		params->iter_count = WPA_GET_BE16(hdr.payload);
	else if (hdr.length == 4)
		params->iter_count = WPA_GET_BE32(hdr.payload);
	else {
		wpa_hexdump(MSG_DEBUG, "PKCS #5: Unsupported INTEGER value "
			    " (iterationCount)",
			    hdr.payload, hdr.length);
		return -1;
	}
	wpa_printf(MSG_DEBUG, "PKCS #5: iterationCount=0x%x",
		   params->iter_count);
	if (params->iter_count == 0 || params->iter_count > 0xffff) {
		wpa_printf(MSG_INFO, "PKCS #5: Unsupported "
			   "iterationCount=0x%x", params->iter_count);
		return -1;
	}

	return 0;
}


static struct crypto_cipher * pkcs5_crypto_init(struct pkcs5_params *params,
						const char *passwd)
{
	unsigned int i;
	u8 hash[MD5_MAC_LEN];
	const u8 *addr[2];
	size_t len[2];

	if (params->alg != PKCS5_ALG_MD5_DES_CBC)
		return NULL;

	addr[0] = (const u8 *) passwd;
	len[0] = os_strlen(passwd);
	addr[1] = params->salt;
	len[1] = params->salt_len;
	if (md5_vector(2, addr, len, hash) < 0)
		return NULL;
	addr[0] = hash;
	len[0] = MD5_MAC_LEN;
	for (i = 1; i < params->iter_count; i++) {
		if (md5_vector(1, addr, len, hash) < 0)
			return NULL;
	}
	/* TODO: DES key parity bits(?) */
	wpa_hexdump_key(MSG_DEBUG, "PKCS #5: DES key", hash, 8);
	wpa_hexdump_key(MSG_DEBUG, "PKCS #5: DES IV", hash + 8, 8);

	return crypto_cipher_init(CRYPTO_CIPHER_ALG_DES, hash + 8, hash, 8);
}


u8 * pkcs5_decrypt(const u8 *enc_alg, size_t enc_alg_len,
		   const u8 *enc_data, size_t enc_data_len,
		   const char *passwd, size_t *data_len)
{
	struct crypto_cipher *ctx;
	u8 *eb, pad;
	struct pkcs5_params params;
	unsigned int i;

	if (pkcs5_get_params(enc_alg, enc_alg_len, &params) < 0) {
		wpa_printf(MSG_DEBUG, "PKCS #5: Unsupported parameters");
		return NULL;
	}

	ctx = pkcs5_crypto_init(&params, passwd);
	if (ctx == NULL) {
		wpa_printf(MSG_DEBUG, "PKCS #5: Failed to initialize crypto");
		return NULL;
	}

	/* PKCS #5, Section 7 - Decryption process */
	if (enc_data_len < 16 || enc_data_len % 8) {
		wpa_printf(MSG_INFO, "PKCS #5: invalid length of ciphertext "
			   "%d", (int) enc_data_len);
		crypto_cipher_deinit(ctx);
		return NULL;
	}

	eb = os_malloc(enc_data_len);
	if (eb == NULL) {
		crypto_cipher_deinit(ctx);
		return NULL;
	}

	if (crypto_cipher_decrypt(ctx, enc_data, eb, enc_data_len) < 0) {
		wpa_printf(MSG_DEBUG, "PKCS #5: Failed to decrypt EB");
		crypto_cipher_deinit(ctx);
		os_free(eb);
		return NULL;
	}
	crypto_cipher_deinit(ctx);

	pad = eb[enc_data_len - 1];
	if (pad > 8) {
		wpa_printf(MSG_INFO, "PKCS #5: Invalid PS octet 0x%x", pad);
		os_free(eb);
		return NULL;
	}
	for (i = enc_data_len - pad; i < enc_data_len; i++) {
		if (eb[i] != pad) {
			wpa_hexdump(MSG_INFO, "PKCS #5: Invalid PS",
				    eb + enc_data_len - pad, pad);
			os_free(eb);
			return NULL;
		}
	}

	wpa_hexdump_key(MSG_MSGDUMP, "PKCS #5: message M (encrypted key)",
			eb, enc_data_len - pad);

	*data_len = enc_data_len - pad;
	return eb;
}