348 lines
8.4 KiB
C
348 lines
8.4 KiB
C
/*
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* CTR with CBC-MAC Protocol (CCMP)
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* Copyright (c) 2010, Jouni Malinen <j@w1.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Alternatively, this software may be distributed under the terms of BSD
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* license.
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*
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* See README and COPYING for more details.
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*/
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#include "utils/includes.h"
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#include "utils/common.h"
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#include "common/ieee802_11_defs.h"
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#include "crypto/aes.h"
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#include "wlantest.h"
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static void ccmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
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u8 *aad, size_t *aad_len, u8 *nonce)
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{
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u16 fc, stype, seq;
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int qos = 0, addr4 = 0;
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u8 *pos;
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nonce[0] = 0;
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fc = le_to_host16(hdr->frame_control);
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stype = WLAN_FC_GET_STYPE(fc);
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if ((fc & (WLAN_FC_TODS | WLAN_FC_FROMDS)) ==
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(WLAN_FC_TODS | WLAN_FC_FROMDS))
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addr4 = 1;
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if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_DATA) {
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fc &= ~0x0070; /* Mask subtype bits */
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if (stype & 0x08) {
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const u8 *qc;
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qos = 1;
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fc &= ~WLAN_FC_ORDER;
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qc = (const u8 *) (hdr + 1);
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if (addr4)
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qc += ETH_ALEN;
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nonce[0] = qc[0] & 0x0f;
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}
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} else if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_MGMT)
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nonce[0] |= 0x10; /* Management */
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fc &= ~(WLAN_FC_RETRY | WLAN_FC_PWRMGT | WLAN_FC_MOREDATA);
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fc |= WLAN_FC_ISWEP;
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WPA_PUT_LE16(aad, fc);
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pos = aad + 2;
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os_memcpy(pos, hdr->addr1, 3 * ETH_ALEN);
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pos += 3 * ETH_ALEN;
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seq = le_to_host16(hdr->seq_ctrl);
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seq &= ~0xfff0; /* Mask Seq#; do not modify Frag# */
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WPA_PUT_LE16(pos, seq);
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pos += 2;
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os_memcpy(pos, hdr + 1, addr4 * ETH_ALEN + qos * 2);
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pos += addr4 * ETH_ALEN;
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if (qos) {
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pos[0] &= 0x70;
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if (1 /* FIX: either device has SPP A-MSDU Capab = 0 */)
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pos[0] &= 0x80;
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pos++;
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*pos++ = 0x00;
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}
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*aad_len = pos - aad;
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os_memcpy(nonce + 1, hdr->addr2, ETH_ALEN);
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nonce[7] = data[7]; /* PN5 */
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nonce[8] = data[6]; /* PN4 */
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nonce[9] = data[5]; /* PN3 */
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nonce[10] = data[4]; /* PN2 */
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nonce[11] = data[1]; /* PN1 */
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nonce[12] = data[0]; /* PN0 */
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}
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static void xor_aes_block(u8 *dst, const u8 *src)
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{
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u32 *d = (u32 *) dst;
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u32 *s = (u32 *) src;
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*d++ ^= *s++;
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*d++ ^= *s++;
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*d++ ^= *s++;
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*d++ ^= *s++;
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}
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u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
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const u8 *data, size_t data_len, size_t *decrypted_len)
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{
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u8 aad[2 + 30], nonce[13];
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size_t aad_len;
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u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
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void *aes;
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const u8 *m, *mpos, *mic;
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size_t mlen, last;
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int i;
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u8 *plain, *ppos;
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u8 t[8];
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if (data_len < 8 + 8)
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return NULL;
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plain = os_malloc(data_len);
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if (plain == NULL)
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return NULL;
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aes = aes_encrypt_init(tk, 16);
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if (aes == NULL) {
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os_free(plain);
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return NULL;
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}
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m = data + 8;
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mlen = data_len - 8 - 8;
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last = mlen % AES_BLOCK_SIZE;
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os_memset(aad, 0, sizeof(aad));
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ccmp_aad_nonce(hdr, data, &aad[2], &aad_len, nonce);
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WPA_PUT_BE16(aad, aad_len);
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wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
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wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);
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/* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */
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/* A_i = Flags | Nonce N | Counter i */
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a[0] = 0x01; /* Flags = L' */
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os_memcpy(&a[1], nonce, 13);
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/* Decryption */
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mic = data + data_len - 8;
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wpa_hexdump(MSG_EXCESSIVE, "CCMP U", mic, 8);
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/* U = T XOR S_0; S_0 = E(K, A_0) */
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WPA_PUT_BE16(&a[14], 0);
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aes_encrypt(aes, a, x);
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for (i = 0; i < 8; i++)
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t[i] = mic[i] ^ x[i];
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wpa_hexdump(MSG_EXCESSIVE, "CCMP T", t, 8);
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/* plaintext = msg XOR (S_1 | S_2 | ... | S_n) */
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ppos = plain;
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mpos = m;
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for (i = 1; i <= mlen / AES_BLOCK_SIZE; i++) {
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WPA_PUT_BE16(&a[14], i);
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/* S_i = E(K, A_i) */
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aes_encrypt(aes, a, ppos);
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xor_aes_block(ppos, mpos);
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ppos += AES_BLOCK_SIZE;
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mpos += AES_BLOCK_SIZE;
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}
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if (last) {
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WPA_PUT_BE16(&a[14], i);
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aes_encrypt(aes, a, ppos);
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/* XOR zero-padded last block */
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for (i = 0; i < last; i++)
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*ppos++ ^= *mpos++;
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}
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wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen);
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/* Authentication */
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/* B_0: Flags | Nonce N | l(m) */
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b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */;
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os_memcpy(&b[1], nonce, 13);
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WPA_PUT_BE16(&b[14], mlen);
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wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
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aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */
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wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
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xor_aes_block(aad, x);
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aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */
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wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
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AES_BLOCK_SIZE);
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xor_aes_block(&aad[AES_BLOCK_SIZE], x);
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aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
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*/
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ppos = plain;
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for (i = 0; i < mlen / AES_BLOCK_SIZE; i++) {
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/* X_i+1 = E(K, X_i XOR B_i) */
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xor_aes_block(x, ppos);
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ppos += AES_BLOCK_SIZE;
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aes_encrypt(aes, x, x);
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}
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if (last) {
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/* XOR zero-padded last block */
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for (i = 0; i < last; i++)
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x[i] ^= *ppos++;
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aes_encrypt(aes, x, x);
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}
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aes_encrypt_deinit(aes);
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if (os_memcmp(x, t, 8) != 0) {
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wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame from " MACSTR,
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MAC2STR(hdr->addr2));
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os_free(plain);
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return NULL;
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}
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*decrypted_len = mlen;
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return plain;
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}
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void ccmp_get_pn(u8 *pn, const u8 *data)
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{
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pn[0] = data[7]; /* PN5 */
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pn[1] = data[6]; /* PN4 */
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pn[2] = data[5]; /* PN3 */
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pn[3] = data[4]; /* PN2 */
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pn[4] = data[1]; /* PN1 */
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pn[5] = data[0]; /* PN0 */
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}
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u8 * ccmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
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u8 *pn, int keyid, size_t *encrypted_len)
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{
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u8 aad[2 + 30], nonce[13];
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size_t aad_len;
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u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
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void *aes;
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u8 *crypt, *pos, *ppos, *mpos;
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size_t plen, last;
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struct ieee80211_hdr *hdr;
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int i;
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if (len < hdrlen || hdrlen < 24)
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return NULL;
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plen = len - hdrlen;
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last = plen % AES_BLOCK_SIZE;
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crypt = os_malloc(hdrlen + 8 + plen + 8);
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if (crypt == NULL)
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return NULL;
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os_memcpy(crypt, frame, hdrlen);
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hdr = (struct ieee80211_hdr *) crypt;
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hdr->frame_control |= host_to_le16(WLAN_FC_ISWEP);
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pos = crypt + hdrlen;
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*pos++ = pn[5]; /* PN0 */
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*pos++ = pn[4]; /* PN1 */
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*pos++ = 0x20 | (keyid << 6);
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*pos++ = pn[3]; /* PN2 */
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*pos++ = pn[2]; /* PN3 */
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*pos++ = pn[1]; /* PN4 */
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*pos++ = pn[0]; /* PN5 */
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aes = aes_encrypt_init(tk, 16);
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if (aes == NULL) {
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os_free(crypt);
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return NULL;
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}
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os_memset(aad, 0, sizeof(aad));
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ccmp_aad_nonce(hdr, crypt + hdrlen, &aad[2], &aad_len, nonce);
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WPA_PUT_BE16(aad, aad_len);
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wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
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wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);
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/* Authentication */
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/* B_0: Flags | Nonce N | l(m) */
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b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */;
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os_memcpy(&b[1], nonce, 13);
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WPA_PUT_BE16(&b[14], plen);
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wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
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aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */
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wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
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xor_aes_block(aad, x);
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aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */
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wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
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AES_BLOCK_SIZE);
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xor_aes_block(&aad[AES_BLOCK_SIZE], x);
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aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
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*/
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ppos = frame + hdrlen;
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for (i = 0; i < plen / AES_BLOCK_SIZE; i++) {
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/* X_i+1 = E(K, X_i XOR B_i) */
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xor_aes_block(x, ppos);
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ppos += AES_BLOCK_SIZE;
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aes_encrypt(aes, x, x);
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}
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if (last) {
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/* XOR zero-padded last block */
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for (i = 0; i < last; i++)
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x[i] ^= *ppos++;
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aes_encrypt(aes, x, x);
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}
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/* Encryption */
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/* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */
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/* A_i = Flags | Nonce N | Counter i */
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a[0] = 0x01; /* Flags = L' */
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os_memcpy(&a[1], nonce, 13);
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ppos = crypt + hdrlen + 8;
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/* crypt = msg XOR (S_1 | S_2 | ... | S_n) */
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mpos = frame + hdrlen;
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for (i = 1; i <= plen / AES_BLOCK_SIZE; i++) {
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WPA_PUT_BE16(&a[14], i);
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/* S_i = E(K, A_i) */
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aes_encrypt(aes, a, ppos);
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xor_aes_block(ppos, mpos);
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ppos += AES_BLOCK_SIZE;
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mpos += AES_BLOCK_SIZE;
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}
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if (last) {
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WPA_PUT_BE16(&a[14], i);
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aes_encrypt(aes, a, ppos);
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/* XOR zero-padded last block */
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for (i = 0; i < last; i++)
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*ppos++ ^= *mpos++;
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}
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wpa_hexdump(MSG_EXCESSIVE, "CCMP T", x, 8);
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/* U = T XOR S_0; S_0 = E(K, A_0) */
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WPA_PUT_BE16(&a[14], 0);
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aes_encrypt(aes, a, b);
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for (i = 0; i < 8; i++)
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ppos[i] = x[i] ^ b[i];
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wpa_hexdump(MSG_EXCESSIVE, "CCMP U", ppos, 8);
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wpa_hexdump(MSG_EXCESSIVE, "CCMP encrypted", crypt + hdrlen + 8, plen);
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aes_encrypt_deinit(aes);
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*encrypted_len = hdrlen + 8 + plen + 8;
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return crypt;
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}
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