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/*
* Wired Equivalent Privacy (WEP)
* Copyright (c) 2010, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "utils/includes.h"
#include "utils/common.h"
#include "common/ieee802_11_defs.h"
#include "wlantest.h"
void wep_crypt(u8 *key, u8 *buf, size_t plen)
{
u32 i, j, k;
u8 S[256];
#define S_SWAP(a,b) do { u8 t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
u8 *pos;
/* Setup RC4 state */
for (i = 0; i < 256; i++)
S[i] = i;
j = 0;
for (i = 0; i < 256; i++) {
j = (j + S[i] + key[i & 0x0f]) & 0xff;
S_SWAP(i, j);
}
/* Apply RC4 to data */
pos = buf;
i = j = 0;
for (k = 0; k < plen; k++) {
i = (i + 1) & 0xff;
j = (j + S[i]) & 0xff;
S_SWAP(i, j);
*pos ^= S[(S[i] + S[j]) & 0xff];
pos++;
}
}
static int try_wep(const u8 *key, size_t key_len, const u8 *data,
size_t data_len, u8 *plain)
{
u32 icv, rx_icv;
u8 k[16];
int i, j;
for (i = 0, j = 0; i < sizeof(k); i++) {
k[i] = key[j];
j++;
if (j >= key_len)
j = 0;
}
os_memcpy(plain, data, data_len);
wep_crypt(k, plain, data_len);
icv = crc32(plain, data_len - 4);
rx_icv = WPA_GET_LE32(plain + data_len - 4);
if (icv != rx_icv)
return -1;
return 0;
}
u8 * wep_decrypt(struct wlantest *wt, const struct ieee80211_hdr *hdr,
const u8 *data, size_t data_len, size_t *decrypted_len)
{
u8 *plain;
struct wlantest_wep *w;
int found = 0;
u8 key[16];
if (dl_list_empty(&wt->wep))
return NULL;
if (data_len < 4 + 4)
return NULL;
plain = os_malloc(data_len - 4);
if (plain == NULL)
return NULL;
dl_list_for_each(w, &wt->wep, struct wlantest_wep, list) {
os_memcpy(key, data, 3);
os_memcpy(key + 3, w->key, w->key_len);
if (try_wep(key, 3 + w->key_len, data + 4, data_len - 4, plain)
== 0) {
found = 1;
break;
}
}
if (!found) {
os_free(plain);
return NULL;
}
*decrypted_len = data_len - 4 - 4;
return plain;
}
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