projects / thirdparty / hostap.git / blame
| Commit | Line | Data |
|---|---|---|
| 2e479416 JM |
1 | /* |
| 2 | * Wired Equivalent Privacy (WEP) | |
| 3 | * Copyright (c) 2010, Jouni Malinen <j@w1.fi> | |
| 4 | * | |
| 0f3d578e JM |
5 | * This software may be distributed under the terms of the BSD license. |
| 6 | * See README for more details. | |
| 2e479416 JM |
7 | */ |
| 8 | ||
| 9 | #include "utils/includes.h" | |
| 10 | ||
| 11 | #include "utils/common.h" | |
| 12 | #include "common/ieee802_11_defs.h" | |
| 13 | #include "wlantest.h" | |
| 14 | ||
| 15 | ||
| 16 | void wep_crypt(u8 *key, u8 *buf, size_t plen) | |
| 17 | { | |
| 18 | u32 i, j, k; | |
| 19 | u8 S[256]; | |
| 20 | #define S_SWAP(a,b) do { u8 t = S[a]; S[a] = S[b]; S[b] = t; } while(0) | |
| 21 | u8 *pos; | |
| 22 | ||
| 23 | /* Setup RC4 state */ | |
| 24 | for (i = 0; i < 256; i++) | |
| 25 | S[i] = i; | |
| 26 | j = 0; | |
| 27 | for (i = 0; i < 256; i++) { | |
| 28 | j = (j + S[i] + key[i & 0x0f]) & 0xff; | |
| 29 | S_SWAP(i, j); | |
| 30 | } | |
| 31 | ||
| 32 | /* Apply RC4 to data */ | |
| 33 | pos = buf; | |
| 34 | i = j = 0; | |
| 35 | for (k = 0; k < plen; k++) { | |
| 36 | i = (i + 1) & 0xff; | |
| 37 | j = (j + S[i]) & 0xff; | |
| 38 | S_SWAP(i, j); | |
| 39 | *pos ^= S[(S[i] + S[j]) & 0xff]; | |
| 40 | pos++; | |
| 41 | } | |
| 42 | } | |
| 43 | ||
| 44 | ||
| 45 | static int try_wep(const u8 *key, size_t key_len, const u8 *data, | |
| 46 | size_t data_len, u8 *plain) | |
| 47 | { | |
| 48 | u32 icv, rx_icv; | |
| 49 | u8 k[16]; | |
| 50 | int i, j; | |
| 51 | ||
| 52 | for (i = 0, j = 0; i < sizeof(k); i++) { | |
| 53 | k[i] = key[j]; | |
| 54 | j++; | |
| 55 | if (j >= key_len) | |
| 56 | j = 0; | |
| 57 | } | |
| 58 | ||
| 59 | os_memcpy(plain, data, data_len); | |
| 60 | wep_crypt(k, plain, data_len); | |
| 61 | icv = crc32(plain, data_len - 4); | |
| 62 | rx_icv = WPA_GET_LE32(plain + data_len - 4); | |
| 63 | if (icv != rx_icv) | |
| 64 | return -1; | |
| 65 | ||
| 66 | return 0; | |
| 67 | } | |
| 68 | ||
| 69 | ||
| 70 | u8 * wep_decrypt(struct wlantest *wt, const struct ieee80211_hdr *hdr, | |
| 71 | const u8 *data, size_t data_len, size_t *decrypted_len) | |
| 72 | { | |
| 73 | u8 *plain; | |
| 74 | struct wlantest_wep *w; | |
| 75 | int found = 0; | |
| 76 | u8 key[16]; | |
| 77 | ||
| 78 | if (dl_list_empty(&wt->wep)) | |
| 79 | return NULL; | |
| 80 | ||
| 81 | if (data_len < 4 + 4) | |
| 82 | return NULL; | |
| 83 | plain = os_malloc(data_len - 4); | |
| 84 | if (plain == NULL) | |
| 85 | return NULL; | |
| 86 | ||
| 87 | dl_list_for_each(w, &wt->wep, struct wlantest_wep, list) { | |
| 88 | os_memcpy(key, data, 3); | |
| 89 | os_memcpy(key + 3, w->key, w->key_len); | |
| 90 | if (try_wep(key, 3 + w->key_len, data + 4, data_len - 4, plain) | |
| 91 | == 0) { | |
| 92 | found = 1; | |
| 93 | break; | |
| 94 | } | |
| 95 | } | |
| 96 | if (!found) { | |
| 97 | os_free(plain); | |
| 98 | return NULL; | |
| 99 | } | |
| 100 | ||
| 101 | *decrypted_len = data_len - 4 - 4; | |
| 102 | return plain; | |
| 103 | } |