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// SPDX-License-Identifier: (GPL-2.0 OR MPL-1.1)
/* src/p80211/p80211wep.c
*
* WEP encode/decode for P80211.
*
* Copyright (C) 2002 AbsoluteValue Systems, Inc. All Rights Reserved.
* --------------------------------------------------------------------
*
* linux-wlan
*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU Public License version 2 (the "GPL"), in which
* case the provisions of the GPL are applicable instead of the
* above. If you wish to allow the use of your version of this file
* only under the terms of the GPL and not to allow others to use
* your version of this file under the MPL, indicate your decision
* by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL. If you do not delete
* the provisions above, a recipient may use your version of this
* file under either the MPL or the GPL.
*
* --------------------------------------------------------------------
*
* Inquiries regarding the linux-wlan Open Source project can be
* made directly to:
*
* AbsoluteValue Systems Inc.
* info@linux-wlan.com
* http://www.linux-wlan.com
*
* --------------------------------------------------------------------
*
* Portions of the development of this software were funded by
* Intersil Corporation as part of PRISM(R) chipset product development.
*
* --------------------------------------------------------------------
*/
/*================================================================*/
/* System Includes */
#include <linux/crc32.h>
#include <linux/netdevice.h>
#include <linux/wireless.h>
#include <linux/random.h>
#include <linux/kernel.h>
#include "p80211hdr.h"
#include "p80211types.h"
#include "p80211msg.h"
#include "p80211conv.h"
#include "p80211netdev.h"
#define WEP_KEY(x) (((x) & 0xC0) >> 6)
/* keylen in bytes! */
int wep_change_key(struct wlandevice *wlandev, int keynum, u8 *key, int keylen)
{
if (keylen < 0)
return -1;
if (keylen >= MAX_KEYLEN)
return -1;
if (!key)
return -1;
if (keynum < 0)
return -1;
if (keynum >= NUM_WEPKEYS)
return -1;
wlandev->wep_keylens[keynum] = keylen;
memcpy(wlandev->wep_keys[keynum], key, keylen);
return 0;
}
/*
* 4-byte IV at start of buffer, 4-byte ICV at end of buffer.
* if successful, buf start is payload begin, length -= 8;
*/
int wep_decrypt(struct wlandevice *wlandev, u8 *buf, u32 len, int key_override,
u8 *iv, u8 *icv)
{
u32 i, j, k, crc, keylen;
u8 s[256], key[64], c_crc[4];
u8 keyidx;
/* Needs to be at least 8 bytes of payload */
if (len <= 0)
return -1;
/* initialize the first bytes of the key from the IV */
key[0] = iv[0];
key[1] = iv[1];
key[2] = iv[2];
keyidx = WEP_KEY(iv[3]);
if (key_override >= 0)
keyidx = key_override;
if (keyidx >= NUM_WEPKEYS)
return -2;
keylen = wlandev->wep_keylens[keyidx];
if (keylen == 0)
return -3;
/* copy the rest of the key over from the designated key */
memcpy(key + 3, wlandev->wep_keys[keyidx], keylen);
keylen += 3; /* add in IV bytes */
/* set up the 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 % keylen]) & 0xff;
swap(i, j);
}
/* Apply the RC4 to the data, update the CRC32 */
i = 0;
j = 0;
for (k = 0; k < len; k++) {
i = (i + 1) & 0xff;
j = (j + s[i]) & 0xff;
swap(i, j);
buf[k] ^= s[(s[i] + s[j]) & 0xff];
}
crc = ~crc32_le(~0, buf, len);
/* now let's check the crc */
c_crc[0] = crc;
c_crc[1] = crc >> 8;
c_crc[2] = crc >> 16;
c_crc[3] = crc >> 24;
for (k = 0; k < 4; k++) {
i = (i + 1) & 0xff;
j = (j + s[i]) & 0xff;
swap(i, j);
if ((c_crc[k] ^ s[(s[i] + s[j]) & 0xff]) != icv[k])
return -(4 | (k << 4)); /* ICV mismatch */
}
return 0;
}
/* encrypts in-place. */
int wep_encrypt(struct wlandevice *wlandev, u8 *buf,
u8 *dst, u32 len, int keynum, u8 *iv, u8 *icv)
{
u32 i, j, k, crc, keylen;
u8 s[256], key[64];
/* no point in WEPping an empty frame */
if (len <= 0)
return -1;
/* we need to have a real key.. */
if (keynum >= NUM_WEPKEYS)
return -2;
keylen = wlandev->wep_keylens[keynum];
if (keylen <= 0)
return -3;
/* use a random IV. And skip known weak ones. */
get_random_bytes(iv, 3);
while ((iv[1] == 0xff) && (iv[0] >= 3) && (iv[0] < keylen))
get_random_bytes(iv, 3);
iv[3] = (keynum & 0x03) << 6;
key[0] = iv[0];
key[1] = iv[1];
key[2] = iv[2];
/* copy the rest of the key over from the designated key */
memcpy(key + 3, wlandev->wep_keys[keynum], keylen);
keylen += 3; /* add in IV bytes */
/* set up the 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 % keylen]) & 0xff;
swap(i, j);
}
/* Update CRC32 then apply RC4 to the data */
i = 0;
j = 0;
for (k = 0; k < len; k++) {
i = (i + 1) & 0xff;
j = (j + s[i]) & 0xff;
swap(i, j);
dst[k] = buf[k] ^ s[(s[i] + s[j]) & 0xff];
}
crc = ~crc32_le(~0, buf, len);
/* now let's encrypt the crc */
icv[0] = crc;
icv[1] = crc >> 8;
icv[2] = crc >> 16;
icv[3] = crc >> 24;
for (k = 0; k < 4; k++) {
i = (i + 1) & 0xff;
j = (j + s[i]) & 0xff;
swap(i, j);
icv[k] ^= s[(s[i] + s[j]) & 0xff];
}
return 0;
}
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