| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame] | 1 | /* |
| 2 | * Wired Equivalent Privacy (WEP) |
| 3 | * Copyright (c) 2010, Jouni Malinen <j@w1.fi> |
| 4 | * |
| 5 | * This software may be distributed under the terms of the BSD license. |
| 6 | * See README for more details. |
| 7 | */ |
| 8 | |
| 9 | #include "utils/includes.h" |
| 10 | |
| 11 | #include "utils/common.h" |
| 12 | #include "utils/crc32.h" |
| 13 | #include "common/ieee802_11_defs.h" |
| 14 | #include "wlantest.h" |
| 15 | |
| 16 | |
| 17 | void wep_crypt(u8 *key, u8 *buf, size_t plen) |
| 18 | { |
| 19 | u32 i, j, k; |
| 20 | u8 S[256]; |
| 21 | #define S_SWAP(a,b) do { u8 t = S[a]; S[a] = S[b]; S[b] = t; } while(0) |
| 22 | u8 *pos; |
| 23 | |
| 24 | /* Setup RC4 state */ |
| 25 | for (i = 0; i < 256; i++) |
| 26 | S[i] = i; |
| 27 | j = 0; |
| 28 | for (i = 0; i < 256; i++) { |
| 29 | j = (j + S[i] + key[i & 0x0f]) & 0xff; |
| 30 | S_SWAP(i, j); |
| 31 | } |
| 32 | |
| 33 | /* Apply RC4 to data */ |
| 34 | pos = buf; |
| 35 | i = j = 0; |
| 36 | for (k = 0; k < plen; k++) { |
| 37 | i = (i + 1) & 0xff; |
| 38 | j = (j + S[i]) & 0xff; |
| 39 | S_SWAP(i, j); |
| 40 | *pos ^= S[(S[i] + S[j]) & 0xff]; |
| 41 | pos++; |
| 42 | } |
| 43 | } |
| 44 | |
| 45 | |
| 46 | static int try_wep(const u8 *key, size_t key_len, const u8 *data, |
| 47 | size_t data_len, u8 *plain) |
| 48 | { |
| 49 | u32 icv, rx_icv; |
| 50 | u8 k[16]; |
| 51 | int i, j; |
| 52 | |
| 53 | for (i = 0, j = 0; i < sizeof(k); i++) { |
| 54 | k[i] = key[j]; |
| 55 | j++; |
| 56 | if (j >= key_len) |
| 57 | j = 0; |
| 58 | } |
| 59 | |
| 60 | os_memcpy(plain, data, data_len); |
| 61 | wep_crypt(k, plain, data_len); |
| 62 | icv = ieee80211_crc32(plain, data_len - 4); |
| 63 | rx_icv = WPA_GET_LE32(plain + data_len - 4); |
| 64 | if (icv != rx_icv) |
| 65 | return -1; |
| 66 | |
| 67 | return 0; |
| 68 | } |
| 69 | |
| 70 | |
| 71 | u8 * wep_decrypt(struct wlantest *wt, const struct ieee80211_hdr *hdr, |
| 72 | const u8 *data, size_t data_len, size_t *decrypted_len) |
| 73 | { |
| 74 | u8 *plain; |
| 75 | struct wlantest_wep *w; |
| 76 | int found = 0; |
| 77 | u8 key[16]; |
| 78 | |
| 79 | if (dl_list_empty(&wt->wep)) |
| 80 | return NULL; |
| 81 | |
| 82 | if (data_len < 4 + 4) |
| 83 | return NULL; |
| 84 | plain = os_malloc(data_len - 4); |
| 85 | if (plain == NULL) |
| 86 | return NULL; |
| 87 | |
| 88 | dl_list_for_each(w, &wt->wep, struct wlantest_wep, list) { |
| 89 | os_memcpy(key, data, 3); |
| 90 | os_memcpy(key + 3, w->key, w->key_len); |
| 91 | if (try_wep(key, 3 + w->key_len, data + 4, data_len - 4, plain) |
| 92 | == 0) { |
| 93 | found = 1; |
| 94 | break; |
| 95 | } |
| 96 | } |
| 97 | if (!found) { |
| 98 | os_free(plain); |
| 99 | return NULL; |
| 100 | } |
| 101 | |
| 102 | *decrypted_len = data_len - 4 - 4; |
| 103 | return plain; |
| 104 | } |