2 * Software WEP encryption implementation
3 * Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
4 * Copyright 2003, Instant802 Networks, Inc.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <linux/config.h>
12 #include <linux/version.h>
13 #include <linux/netdevice.h>
14 #include <linux/types.h>
15 #include <linux/random.h>
16 #include <linux/compiler.h>
18 #include <net/ieee80211.h>
19 #include "ieee80211_i.h"
23 static const __u32 crc32_table
[256] = {
24 0x00000000L
, 0x77073096L
, 0xee0e612cL
, 0x990951baL
, 0x076dc419L
,
25 0x706af48fL
, 0xe963a535L
, 0x9e6495a3L
, 0x0edb8832L
, 0x79dcb8a4L
,
26 0xe0d5e91eL
, 0x97d2d988L
, 0x09b64c2bL
, 0x7eb17cbdL
, 0xe7b82d07L
,
27 0x90bf1d91L
, 0x1db71064L
, 0x6ab020f2L
, 0xf3b97148L
, 0x84be41deL
,
28 0x1adad47dL
, 0x6ddde4ebL
, 0xf4d4b551L
, 0x83d385c7L
, 0x136c9856L
,
29 0x646ba8c0L
, 0xfd62f97aL
, 0x8a65c9ecL
, 0x14015c4fL
, 0x63066cd9L
,
30 0xfa0f3d63L
, 0x8d080df5L
, 0x3b6e20c8L
, 0x4c69105eL
, 0xd56041e4L
,
31 0xa2677172L
, 0x3c03e4d1L
, 0x4b04d447L
, 0xd20d85fdL
, 0xa50ab56bL
,
32 0x35b5a8faL
, 0x42b2986cL
, 0xdbbbc9d6L
, 0xacbcf940L
, 0x32d86ce3L
,
33 0x45df5c75L
, 0xdcd60dcfL
, 0xabd13d59L
, 0x26d930acL
, 0x51de003aL
,
34 0xc8d75180L
, 0xbfd06116L
, 0x21b4f4b5L
, 0x56b3c423L
, 0xcfba9599L
,
35 0xb8bda50fL
, 0x2802b89eL
, 0x5f058808L
, 0xc60cd9b2L
, 0xb10be924L
,
36 0x2f6f7c87L
, 0x58684c11L
, 0xc1611dabL
, 0xb6662d3dL
, 0x76dc4190L
,
37 0x01db7106L
, 0x98d220bcL
, 0xefd5102aL
, 0x71b18589L
, 0x06b6b51fL
,
38 0x9fbfe4a5L
, 0xe8b8d433L
, 0x7807c9a2L
, 0x0f00f934L
, 0x9609a88eL
,
39 0xe10e9818L
, 0x7f6a0dbbL
, 0x086d3d2dL
, 0x91646c97L
, 0xe6635c01L
,
40 0x6b6b51f4L
, 0x1c6c6162L
, 0x856530d8L
, 0xf262004eL
, 0x6c0695edL
,
41 0x1b01a57bL
, 0x8208f4c1L
, 0xf50fc457L
, 0x65b0d9c6L
, 0x12b7e950L
,
42 0x8bbeb8eaL
, 0xfcb9887cL
, 0x62dd1ddfL
, 0x15da2d49L
, 0x8cd37cf3L
,
43 0xfbd44c65L
, 0x4db26158L
, 0x3ab551ceL
, 0xa3bc0074L
, 0xd4bb30e2L
,
44 0x4adfa541L
, 0x3dd895d7L
, 0xa4d1c46dL
, 0xd3d6f4fbL
, 0x4369e96aL
,
45 0x346ed9fcL
, 0xad678846L
, 0xda60b8d0L
, 0x44042d73L
, 0x33031de5L
,
46 0xaa0a4c5fL
, 0xdd0d7cc9L
, 0x5005713cL
, 0x270241aaL
, 0xbe0b1010L
,
47 0xc90c2086L
, 0x5768b525L
, 0x206f85b3L
, 0xb966d409L
, 0xce61e49fL
,
48 0x5edef90eL
, 0x29d9c998L
, 0xb0d09822L
, 0xc7d7a8b4L
, 0x59b33d17L
,
49 0x2eb40d81L
, 0xb7bd5c3bL
, 0xc0ba6cadL
, 0xedb88320L
, 0x9abfb3b6L
,
50 0x03b6e20cL
, 0x74b1d29aL
, 0xead54739L
, 0x9dd277afL
, 0x04db2615L
,
51 0x73dc1683L
, 0xe3630b12L
, 0x94643b84L
, 0x0d6d6a3eL
, 0x7a6a5aa8L
,
52 0xe40ecf0bL
, 0x9309ff9dL
, 0x0a00ae27L
, 0x7d079eb1L
, 0xf00f9344L
,
53 0x8708a3d2L
, 0x1e01f268L
, 0x6906c2feL
, 0xf762575dL
, 0x806567cbL
,
54 0x196c3671L
, 0x6e6b06e7L
, 0xfed41b76L
, 0x89d32be0L
, 0x10da7a5aL
,
55 0x67dd4accL
, 0xf9b9df6fL
, 0x8ebeeff9L
, 0x17b7be43L
, 0x60b08ed5L
,
56 0xd6d6a3e8L
, 0xa1d1937eL
, 0x38d8c2c4L
, 0x4fdff252L
, 0xd1bb67f1L
,
57 0xa6bc5767L
, 0x3fb506ddL
, 0x48b2364bL
, 0xd80d2bdaL
, 0xaf0a1b4cL
,
58 0x36034af6L
, 0x41047a60L
, 0xdf60efc3L
, 0xa867df55L
, 0x316e8eefL
,
59 0x4669be79L
, 0xcb61b38cL
, 0xbc66831aL
, 0x256fd2a0L
, 0x5268e236L
,
60 0xcc0c7795L
, 0xbb0b4703L
, 0x220216b9L
, 0x5505262fL
, 0xc5ba3bbeL
,
61 0xb2bd0b28L
, 0x2bb45a92L
, 0x5cb36a04L
, 0xc2d7ffa7L
, 0xb5d0cf31L
,
62 0x2cd99e8bL
, 0x5bdeae1dL
, 0x9b64c2b0L
, 0xec63f226L
, 0x756aa39cL
,
63 0x026d930aL
, 0x9c0906a9L
, 0xeb0e363fL
, 0x72076785L
, 0x05005713L
,
64 0x95bf4a82L
, 0xe2b87a14L
, 0x7bb12baeL
, 0x0cb61b38L
, 0x92d28e9bL
,
65 0xe5d5be0dL
, 0x7cdcefb7L
, 0x0bdbdf21L
, 0x86d3d2d4L
, 0xf1d4e242L
,
66 0x68ddb3f8L
, 0x1fda836eL
, 0x81be16cdL
, 0xf6b9265bL
, 0x6fb077e1L
,
67 0x18b74777L
, 0x88085ae6L
, 0xff0f6a70L
, 0x66063bcaL
, 0x11010b5cL
,
68 0x8f659effL
, 0xf862ae69L
, 0x616bffd3L
, 0x166ccf45L
, 0xa00ae278L
,
69 0xd70dd2eeL
, 0x4e048354L
, 0x3903b3c2L
, 0xa7672661L
, 0xd06016f7L
,
70 0x4969474dL
, 0x3e6e77dbL
, 0xaed16a4aL
, 0xd9d65adcL
, 0x40df0b66L
,
71 0x37d83bf0L
, 0xa9bcae53L
, 0xdebb9ec5L
, 0x47b2cf7fL
, 0x30b5ffe9L
,
72 0xbdbdf21cL
, 0xcabac28aL
, 0x53b39330L
, 0x24b4a3a6L
, 0xbad03605L
,
73 0xcdd70693L
, 0x54de5729L
, 0x23d967bfL
, 0xb3667a2eL
, 0xc4614ab8L
,
74 0x5d681b02L
, 0x2a6f2b94L
, 0xb40bbe37L
, 0xc30c8ea1L
, 0x5a05df1bL
,
79 void ieee80211_wep_init(struct ieee80211_local
*local
)
81 /* start WEP IV from a random value */
82 get_random_bytes(&local
->wep_iv
, WEP_IV_LEN
);
86 static inline int ieee80211_wep_weak_iv(u32 iv
, int keylen
)
88 /* Fluhrer, Mantin, and Shamir have reported weaknesses in the
89 * key scheduling algorithm of RC4. At least IVs (KeyByte + 3,
90 * 0xff, N) can be used to speedup attacks, so avoid using them. */
91 if ((iv
& 0xff00) == 0xff00) {
92 u8 B
= (iv
>> 16) & 0xff;
93 if (B
>= 3 && B
< 3 + keylen
)
100 void ieee80211_wep_get_iv(struct ieee80211_local
*local
,
101 struct ieee80211_key
*key
, u8
*iv
)
104 if (ieee80211_wep_weak_iv(local
->wep_iv
, key
->keylen
))
105 local
->wep_iv
+= 0x0100;
110 *iv
++ = (local
->wep_iv
>> 16) & 0xff;
111 *iv
++ = (local
->wep_iv
>> 8) & 0xff;
112 *iv
++ = local
->wep_iv
& 0xff;
113 *iv
++ = key
->keyidx
<< 6;
117 u8
* ieee80211_wep_add_iv(struct ieee80211_local
*local
,
119 struct ieee80211_key
*key
)
121 struct ieee80211_hdr
*hdr
= (struct ieee80211_hdr
*) skb
->data
;
126 fc
= le16_to_cpu(hdr
->frame_control
);
128 hdr
->frame_control
= cpu_to_le16(fc
);
130 if ((skb_headroom(skb
) < WEP_IV_LEN
||
131 skb_tailroom(skb
) < WEP_ICV_LEN
)) {
132 I802_DEBUG_INC(local
->tx_expand_skb_head
);
133 if (unlikely(pskb_expand_head(skb
, WEP_IV_LEN
, WEP_ICV_LEN
,
138 hdrlen
= ieee80211_get_hdrlen(fc
);
139 newhdr
= skb_push(skb
, WEP_IV_LEN
);
140 memmove(newhdr
, newhdr
+ WEP_IV_LEN
, hdrlen
);
141 ieee80211_wep_get_iv(local
, key
, newhdr
+ hdrlen
);
142 return newhdr
+ hdrlen
;
146 void ieee80211_wep_remove_iv(struct ieee80211_local
*local
,
148 struct ieee80211_key
*key
)
150 struct ieee80211_hdr
*hdr
= (struct ieee80211_hdr
*) skb
->data
;
154 fc
= le16_to_cpu(hdr
->frame_control
);
155 hdrlen
= ieee80211_get_hdrlen(fc
);
156 memmove(skb
->data
+ WEP_IV_LEN
, skb
->data
, hdrlen
);
157 skb_pull(skb
, WEP_IV_LEN
);
161 /* Perform WEP encryption using given key. data buffer must have tailroom
162 * for 4-byte ICV. data_len must not include this ICV. Note: this function
163 * does _not_ add IV. data = RC4(data | CRC32(data)) */
164 void ieee80211_wep_encrypt_data(u8
*rc4key
, size_t klen
, u8
*data
,
170 #define S_SWAP(a,b) do { u8 t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
172 /* Setup RC4 state */
173 for (i
= 0; i
< 256; i
++)
177 for (i
= 0; i
< 256; i
++) {
178 j
= (j
+ S
[i
] + rc4key
[kpos
]) & 0xff;
185 /* Compute CRC32 over unencrypted data and apply RC4 to data */
189 for (k
= 0; k
< data_len
; k
++) {
190 crc
= crc32_table
[(crc
^ *pos
) & 0xff] ^ (crc
>> 8);
192 j
= (j
+ S
[i
]) & 0xff;
194 *pos
++ ^= S
[(S
[i
] + S
[j
]) & 0xff];
198 /* Append little-endian CRC32 and encrypt it to produce ICV */
203 for (k
= 0; k
< 4; k
++) {
205 j
= (j
+ S
[i
]) & 0xff;
207 *pos
++ ^= S
[(S
[i
] + S
[j
]) & 0xff];
212 /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
213 * beginning of the buffer 4 bytes of extra space (ICV) in the end of the
214 * buffer will be added. Both IV and ICV will be transmitted, so the
215 * payload length increases with 8 bytes.
217 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
219 int ieee80211_wep_encrypt(struct ieee80211_local
*local
, struct sk_buff
*skb
,
220 struct ieee80211_key
*key
)
226 if (key
== NULL
|| key
->alg
!= ALG_WEP
)
229 klen
= 3 + key
->keylen
;
230 rc4key
= kmalloc(klen
, GFP_ATOMIC
);
234 iv
= ieee80211_wep_add_iv(local
, skb
, key
);
240 len
= skb
->len
- (iv
+ WEP_IV_LEN
- skb
->data
);
242 /* Prepend 24-bit IV to RC4 key */
243 memcpy(rc4key
, iv
, 3);
245 /* Copy rest of the WEP key (the secret part) */
246 memcpy(rc4key
+ 3, key
->key
, key
->keylen
);
248 /* Add room for ICV */
249 skb_put(skb
, WEP_ICV_LEN
);
251 ieee80211_wep_encrypt_data(rc4key
, klen
, iv
+ WEP_IV_LEN
, len
);
259 /* Perform WEP decryption using given key. data buffer includes encrypted
260 * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
261 * Return 0 on success and -1 on ICV mismatch. */
262 int ieee80211_wep_decrypt_data(u8
*rc4key
, size_t klen
, u8
*data
,
267 u8 kpos
, *pos
, crcbuf
[WEP_ICV_LEN
], *cpos
;
269 /* Setup RC4 state */
270 for (i
= 0; i
< 256; i
++)
274 for (i
= 0; i
< 256; i
++) {
275 j
= (j
+ S
[i
] + rc4key
[kpos
]) & 0xff;
282 /* Apply RC4 to data and compute CRC32 over decrypted data */
286 for (k
= 0; k
< data_len
; k
++) {
288 j
= (j
+ S
[i
]) & 0xff;
290 *pos
^= S
[(S
[i
] + S
[j
]) & 0xff];
291 crc
= crc32_table
[(crc
^ *pos
++) & 0xff] ^ (crc
>> 8);
295 /* Decrypt little-endian CRC32 and verify that it matches with the
299 crcbuf
[1] = crc
>> 8;
300 crcbuf
[2] = crc
>> 16;
301 crcbuf
[3] = crc
>> 24;
302 for (k
= 0; k
< WEP_ICV_LEN
; k
++) {
304 j
= (j
+ S
[i
]) & 0xff;
306 if (*cpos
++ != (*pos
++ ^ S
[(S
[i
] + S
[j
]) & 0xff])) {
316 /* Perform WEP decryption on given skb. Buffer includes whole WEP part of
317 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
318 * ICV (4 bytes). skb->len includes both IV and ICV.
320 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
321 * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload
322 * is moved to the beginning of the skb and skb length will be reduced.
324 int ieee80211_wep_decrypt(struct ieee80211_local
*local
, struct sk_buff
*skb
,
325 struct ieee80211_key
*key
)
330 struct ieee80211_hdr
*hdr
= (struct ieee80211_hdr
*) skb
->data
;
336 fc
= le16_to_cpu(hdr
->frame_control
);
337 if (!(fc
& WLAN_FC_ISWEP
))
340 hdrlen
= ieee80211_get_hdrlen(fc
);
342 if (skb
->len
< 8 + hdrlen
)
345 len
= skb
->len
- hdrlen
- 8;
347 keyidx
= skb
->data
[hdrlen
+ 3] >> 6;
349 if (key
== NULL
|| keyidx
!= key
->keyidx
|| key
->alg
!= ALG_WEP
)
352 klen
= 3 + key
->keylen
;
354 rc4key
= kmalloc(klen
, GFP_ATOMIC
);
358 /* Prepend 24-bit IV to RC4 key */
359 memcpy(rc4key
, skb
->data
+ hdrlen
, 3);
361 /* Copy rest of the WEP key (the secret part) */
362 memcpy(rc4key
+ 3, key
->key
, key
->keylen
);
364 if (ieee80211_wep_decrypt_data(rc4key
, klen
,
365 skb
->data
+ hdrlen
+ WEP_IV_LEN
,
367 printk(KERN_DEBUG
"WEP decrypt failed (ICV)\n");
374 skb_trim(skb
, skb
->len
- WEP_ICV_LEN
);
377 memmove(skb
->data
+ WEP_IV_LEN
, skb
->data
, hdrlen
);
378 skb_pull(skb
, WEP_IV_LEN
);
384 int ieee80211_wep_get_keyidx(struct sk_buff
*skb
)
386 struct ieee80211_hdr
*hdr
= (struct ieee80211_hdr
*) skb
->data
;
390 fc
= le16_to_cpu(hdr
->frame_control
);
391 if (!(fc
& WLAN_FC_ISWEP
))
394 hdrlen
= ieee80211_get_hdrlen(fc
);
396 if (skb
->len
< 8 + hdrlen
)
399 return skb
->data
[hdrlen
+ 3] >> 6;
403 u8
* ieee80211_wep_is_weak_iv(struct sk_buff
*skb
, struct ieee80211_key
*key
)
405 struct ieee80211_hdr
*hdr
= (struct ieee80211_hdr
*) skb
->data
;
411 fc
= le16_to_cpu(hdr
->frame_control
);
412 if (!(fc
& WLAN_FC_ISWEP
))
415 hdrlen
= ieee80211_get_hdrlen(fc
);
416 ivpos
= skb
->data
+ hdrlen
;
417 iv
= (ivpos
[0] << 16) | (ivpos
[1] << 8) | ivpos
[2];
419 if (ieee80211_wep_weak_iv(iv
, key
->keylen
))
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