wlantest/ccmp.c - vendor/opensource/hostap - Git at Google

 /*
  * CTR with CBC-MAC Protocol (CCMP)
  * Copyright (c) 2010, Jouni Malinen <j@w1.fi>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * Alternatively, this software may be distributed under the terms of BSD
  * license.
  *
  * See README and COPYING for more details.
  */

 #include "utils/includes.h"

 #include "utils/common.h"
 #include "common/ieee802_11_defs.h"
 #include "crypto/aes.h"
 #include "wlantest.h"


 static void ccmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
 			   u8 *aad, size_t *aad_len, u8 *nonce)
 {
 	u16 fc, stype, seq;
 	int qos = 0, addr4 = 0;
 	u8 *pos;

 	nonce[0] = 0;

 	fc = le_to_host16(hdr->frame_control);
 	stype = WLAN_FC_GET_STYPE(fc);
 	if ((fc & (WLAN_FC_TODS | WLAN_FC_FROMDS)) ==
 	    (WLAN_FC_TODS | WLAN_FC_FROMDS))
 		addr4 = 1;

 	if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_DATA) {
 		fc &= ~0x0070; /* Mask subtype bits */
 		if (stype & 0x08) {
 			const u8 *qc;
 			qos = 1;
 			fc &= ~WLAN_FC_ORDER;
 			qc = (const u8 *) (hdr + 1);
 			if (addr4)
 				qc += ETH_ALEN;
 			nonce[0] = qc[0] & 0x0f;
 		}
 	} else if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_MGMT)
 		nonce[0] |= 0x10; /* Management */

 	fc &= ~(WLAN_FC_RETRY | WLAN_FC_PWRMGT | WLAN_FC_MOREDATA);
 	fc |= WLAN_FC_ISWEP;
 	WPA_PUT_LE16(aad, fc);
 	pos = aad + 2;
 	os_memcpy(pos, hdr->addr1, 3 * ETH_ALEN);
 	pos += 3 * ETH_ALEN;
 	seq = le_to_host16(hdr->seq_ctrl);
 	seq &= ~0xfff0; /* Mask Seq#; do not modify Frag# */
 	WPA_PUT_LE16(pos, seq);
 	pos += 2;

 	os_memcpy(pos, hdr + 1, addr4 * ETH_ALEN + qos * 2);
 	pos += addr4 * ETH_ALEN;
 	if (qos) {
 		pos[0] &= ~0x70;
 		if (1 /* FIX: either device has SPP A-MSDU Capab = 0 */)
 			pos[0] &= ~0x80;
 		pos++;
 		*pos++ = 0x00;
 	}

 	*aad_len = pos - aad;

 	os_memcpy(nonce + 1, hdr->addr2, ETH_ALEN);
 	nonce[7] = data[7]; /* PN5 */
 	nonce[8] = data[6]; /* PN4 */
 	nonce[9] = data[5]; /* PN3 */
 	nonce[10] = data[4]; /* PN2 */
 	nonce[11] = data[1]; /* PN1 */
 	nonce[12] = data[0]; /* PN0 */
 }


 static void xor_aes_block(u8 *dst, const u8 *src)
 {
 	u32 *d = (u32 *) dst;
 	u32 *s = (u32 *) src;
 	*d++ ^= *s++;
 	*d++ ^= *s++;
 	*d++ ^= *s++;
 	*d++ ^= *s++;
 }


 u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 		  const u8 *data, size_t data_len, size_t *decrypted_len)
 {
 	u8 aad[2 + 30], nonce[13];
 	size_t aad_len;
 	u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
 	void *aes;
 	const u8 *m, *mpos, *mic;
 	size_t mlen, last;
 	int i;
 	u8 *plain, *ppos;
 	u8 t[8];

 	if (data_len < 8 + 8)
 		return NULL;

 	plain = os_malloc(data_len + AES_BLOCK_SIZE);
 	if (plain == NULL)
 		return NULL;

 	aes = aes_encrypt_init(tk, 16);
 	if (aes == NULL) {
 		os_free(plain);
 		return NULL;
 	}

 	m = data + 8;
 	mlen = data_len - 8 - 8;
 	last = mlen % AES_BLOCK_SIZE;

 	os_memset(aad, 0, sizeof(aad));
 	ccmp_aad_nonce(hdr, data, &aad[2], &aad_len, nonce);
 	WPA_PUT_BE16(aad, aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);

 	/* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */

 	/* A_i = Flags | Nonce N | Counter i */
 	a[0] = 0x01; /* Flags = L' */
 	os_memcpy(&a[1], nonce, 13);

 	/* Decryption */

 	mic = data + data_len - 8;
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP U", mic, 8);
 	/* U = T XOR S_0; S_0 = E(K, A_0) */
 	WPA_PUT_BE16(&a[14], 0);
 	aes_encrypt(aes, a, x);
 	for (i = 0; i < 8; i++)
 		t[i] = mic[i] ^ x[i];
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP T", t, 8);

 	/* plaintext = msg XOR (S_1 | S_2 | ... | S_n) */
 	ppos = plain;
 	mpos = m;
 	for (i = 1; i <= mlen / AES_BLOCK_SIZE; i++) {
 		WPA_PUT_BE16(&a[14], i);
 		/* S_i = E(K, A_i) */
 		aes_encrypt(aes, a, ppos);
 		xor_aes_block(ppos, mpos);
 		ppos += AES_BLOCK_SIZE;
 		mpos += AES_BLOCK_SIZE;
 	}
 	if (last) {
 		WPA_PUT_BE16(&a[14], i);
 		aes_encrypt(aes, a, ppos);
 		/* XOR zero-padded last block */
 		for (i = 0; i < last; i++)
 			*ppos++ ^= *mpos++;
 	}
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen);

 	/* Authentication */
 	/* B_0: Flags | Nonce N | l(m) */
 	b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */;
 	os_memcpy(&b[1], nonce, 13);
 	WPA_PUT_BE16(&b[14], mlen);

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
 	aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
 	xor_aes_block(aad, x);
 	aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
 		    AES_BLOCK_SIZE);
 	xor_aes_block(&aad[AES_BLOCK_SIZE], x);
 	aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
 						    */

 	ppos = plain;
 	for (i = 0; i < mlen / AES_BLOCK_SIZE; i++) {
 		/* X_i+1 = E(K, X_i XOR B_i) */
 		xor_aes_block(x, ppos);
 		ppos += AES_BLOCK_SIZE;
 		aes_encrypt(aes, x, x);
 	}
 	if (last) {
 		/* XOR zero-padded last block */
 		for (i = 0; i < last; i++)
 			x[i] ^= *ppos++;
 		aes_encrypt(aes, x, x);
 	}

 	aes_encrypt_deinit(aes);

 	if (os_memcmp(x, t, 8) != 0) {
 		u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
 		wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame: A1=" MACSTR
 			   " A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u",
 			   MAC2STR(hdr->addr1), MAC2STR(hdr->addr2),
 			   MAC2STR(hdr->addr3),
 			   WLAN_GET_SEQ_SEQ(seq_ctrl),
 			   WLAN_GET_SEQ_FRAG(seq_ctrl));
 		wpa_hexdump(MSG_DEBUG, "CCMP decrypted", plain, mlen);
 		os_free(plain);
 		return NULL;
 	}

 	*decrypted_len = mlen;
 	return plain;
 }


 void ccmp_get_pn(u8 *pn, const u8 *data)
 {
 	pn[0] = data[7]; /* PN5 */
 	pn[1] = data[6]; /* PN4 */
 	pn[2] = data[5]; /* PN3 */
 	pn[3] = data[4]; /* PN2 */
 	pn[4] = data[1]; /* PN1 */
 	pn[5] = data[0]; /* PN0 */
 }


 u8 * ccmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
 		  u8 *pn, int keyid, size_t *encrypted_len)
 {
 	u8 aad[2 + 30], nonce[13];
 	size_t aad_len;
 	u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
 	void *aes;
 	u8 *crypt, *pos, *ppos, *mpos;
 	size_t plen, last;
 	struct ieee80211_hdr *hdr;
 	int i;

 	if (len < hdrlen || hdrlen < 24)
 		return NULL;
 	plen = len - hdrlen;
 	last = plen % AES_BLOCK_SIZE;

 	crypt = os_malloc(hdrlen + 8 + plen + 8 + AES_BLOCK_SIZE);
 	if (crypt == NULL)
 		return NULL;

 	os_memcpy(crypt, frame, hdrlen);
 	hdr = (struct ieee80211_hdr *) crypt;
 	hdr->frame_control |= host_to_le16(WLAN_FC_ISWEP);
 	pos = crypt + hdrlen;
 	*pos++ = pn[5]; /* PN0 */
 	*pos++ = pn[4]; /* PN1 */
 	*pos++ = 0x00; /* Rsvd */
 	*pos++ = 0x20 | (keyid << 6);
 	*pos++ = pn[3]; /* PN2 */
 	*pos++ = pn[2]; /* PN3 */
 	*pos++ = pn[1]; /* PN4 */
 	*pos++ = pn[0]; /* PN5 */

 	aes = aes_encrypt_init(tk, 16);
 	if (aes == NULL) {
 		os_free(crypt);
 		return NULL;
 	}

 	os_memset(aad, 0, sizeof(aad));
 	ccmp_aad_nonce(hdr, crypt + hdrlen, &aad[2], &aad_len, nonce);
 	WPA_PUT_BE16(aad, aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);

 	/* Authentication */
 	/* B_0: Flags | Nonce N | l(m) */
 	b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */;
 	os_memcpy(&b[1], nonce, 13);
 	WPA_PUT_BE16(&b[14], plen);

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
 	aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
 	xor_aes_block(aad, x);
 	aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
 		    AES_BLOCK_SIZE);
 	xor_aes_block(&aad[AES_BLOCK_SIZE], x);
 	aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
 						    */

 	ppos = frame + hdrlen;
 	for (i = 0; i < plen / AES_BLOCK_SIZE; i++) {
 		/* X_i+1 = E(K, X_i XOR B_i) */
 		xor_aes_block(x, ppos);
 		ppos += AES_BLOCK_SIZE;
 		aes_encrypt(aes, x, x);
 	}
 	if (last) {
 		/* XOR zero-padded last block */
 		for (i = 0; i < last; i++)
 			x[i] ^= *ppos++;
 		aes_encrypt(aes, x, x);
 	}

 	/* Encryption */

 	/* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */

 	/* A_i = Flags | Nonce N | Counter i */
 	a[0] = 0x01; /* Flags = L' */
 	os_memcpy(&a[1], nonce, 13);

 	ppos = crypt + hdrlen + 8;

 	/* crypt = msg XOR (S_1 | S_2 | ... | S_n) */
 	mpos = frame + hdrlen;
 	for (i = 1; i <= plen / AES_BLOCK_SIZE; i++) {
 		WPA_PUT_BE16(&a[14], i);
 		/* S_i = E(K, A_i) */
 		aes_encrypt(aes, a, ppos);
 		xor_aes_block(ppos, mpos);
 		ppos += AES_BLOCK_SIZE;
 		mpos += AES_BLOCK_SIZE;
 	}
 	if (last) {
 		WPA_PUT_BE16(&a[14], i);
 		aes_encrypt(aes, a, ppos);
 		/* XOR zero-padded last block */
 		for (i = 0; i < last; i++)
 			*ppos++ ^= *mpos++;
 	}

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP T", x, 8);
 	/* U = T XOR S_0; S_0 = E(K, A_0) */
 	WPA_PUT_BE16(&a[14], 0);
 	aes_encrypt(aes, a, b);
 	for (i = 0; i < 8; i++)
 		ppos[i] = x[i] ^ b[i];
 	wpa_hexdump(MSG_EXCESSIVE, "CCMP U", ppos, 8);

 	wpa_hexdump(MSG_EXCESSIVE, "CCMP encrypted", crypt + hdrlen + 8, plen);

 	aes_encrypt_deinit(aes);

 	*encrypted_len = hdrlen + 8 + plen + 8;

 	return crypt;
 }
	/*
	* CTR with CBC-MAC Protocol (CCMP)
	* Copyright (c) 2010, Jouni Malinen <j@w1.fi>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* Alternatively, this software may be distributed under the terms of BSD
	* license.
	*
	* See README and COPYING for more details.
	*/

	#include "utils/includes.h"

	#include "utils/common.h"
	#include "common/ieee802_11_defs.h"
	#include "crypto/aes.h"
	#include "wlantest.h"


	static void ccmp_aad_nonce(const struct ieee80211_hdr hdr, const u8 data,
	u8 aad, size_t aad_len, u8 *nonce)
	{
	u16 fc, stype, seq;
	int qos = 0, addr4 = 0;
	u8 *pos;

	nonce[0] = 0;

	fc = le_to_host16(hdr->frame_control);
	stype = WLAN_FC_GET_STYPE(fc);
	if ((fc & (WLAN_FC_TODS \| WLAN_FC_FROMDS)) ==
	(WLAN_FC_TODS \| WLAN_FC_FROMDS))
	addr4 = 1;

	if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_DATA) {
	fc &= ~0x0070; /* Mask subtype bits */
	if (stype & 0x08) {
	const u8 *qc;
	qos = 1;
	fc &= ~WLAN_FC_ORDER;
	qc = (const u8 *) (hdr + 1);
	if (addr4)
	qc += ETH_ALEN;
	nonce[0] = qc[0] & 0x0f;
	}
	} else if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_MGMT)
	nonce[0] \|= 0x10; /* Management */

	fc &= ~(WLAN_FC_RETRY \| WLAN_FC_PWRMGT \| WLAN_FC_MOREDATA);
	fc \|= WLAN_FC_ISWEP;
	WPA_PUT_LE16(aad, fc);
	pos = aad + 2;
	os_memcpy(pos, hdr->addr1, 3 * ETH_ALEN);
	pos += 3 * ETH_ALEN;
	seq = le_to_host16(hdr->seq_ctrl);
	seq &= ~0xfff0; /* Mask Seq#; do not modify Frag# */
	WPA_PUT_LE16(pos, seq);
	pos += 2;

	os_memcpy(pos, hdr + 1, addr4 * ETH_ALEN + qos * 2);
	pos += addr4 * ETH_ALEN;
	if (qos) {
	pos[0] &= ~0x70;
	if (1 /* FIX: either device has SPP A-MSDU Capab = 0 */)
	pos[0] &= ~0x80;
	pos++;
	*pos++ = 0x00;
	}

	*aad_len = pos - aad;

	os_memcpy(nonce + 1, hdr->addr2, ETH_ALEN);
	nonce[7] = data[7]; /* PN5 */
	nonce[8] = data[6]; /* PN4 */
	nonce[9] = data[5]; /* PN3 */
	nonce[10] = data[4]; /* PN2 */
	nonce[11] = data[1]; /* PN1 */
	nonce[12] = data[0]; /* PN0 */
	}


	static void xor_aes_block(u8 dst, const u8 src)
	{
	u32 d = (u32 ) dst;
	u32 s = (u32 ) src;
	d++ ^= s++;
	d++ ^= s++;
	d++ ^= s++;
	d++ ^= s++;
	}


	u8 * ccmp_decrypt(const u8 tk, const struct ieee80211_hdr hdr,
	const u8 data, size_t data_len, size_t decrypted_len)
	{
	u8 aad[2 + 30], nonce[13];
	size_t aad_len;
	u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
	void *aes;
	const u8 m, mpos, *mic;
	size_t mlen, last;
	int i;
	u8 plain, ppos;
	u8 t[8];

	if (data_len < 8 + 8)
	return NULL;

	plain = os_malloc(data_len + AES_BLOCK_SIZE);
	if (plain == NULL)
	return NULL;

	aes = aes_encrypt_init(tk, 16);
	if (aes == NULL) {
	os_free(plain);
	return NULL;
	}

	m = data + 8;
	mlen = data_len - 8 - 8;
	last = mlen % AES_BLOCK_SIZE;

	os_memset(aad, 0, sizeof(aad));
	ccmp_aad_nonce(hdr, data, &aad[2], &aad_len, nonce);
	WPA_PUT_BE16(aad, aad_len);
	wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
	wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);

	/* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */

	/* A_i = Flags \| Nonce N \| Counter i */
	a[0] = 0x01; /* Flags = L' */
	os_memcpy(&a[1], nonce, 13);

	/* Decryption */

	mic = data + data_len - 8;
	wpa_hexdump(MSG_EXCESSIVE, "CCMP U", mic, 8);
	/* U = T XOR S_0; S_0 = E(K, A_0) */
	WPA_PUT_BE16(&a[14], 0);
	aes_encrypt(aes, a, x);
	for (i = 0; i < 8; i++)
	t[i] = mic[i] ^ x[i];
	wpa_hexdump(MSG_EXCESSIVE, "CCMP T", t, 8);

	/* plaintext = msg XOR (S_1 \| S_2 \| ... \| S_n) */
	ppos = plain;
	mpos = m;
	for (i = 1; i <= mlen / AES_BLOCK_SIZE; i++) {
	WPA_PUT_BE16(&a[14], i);
	/* S_i = E(K, A_i) */
	aes_encrypt(aes, a, ppos);
	xor_aes_block(ppos, mpos);
	ppos += AES_BLOCK_SIZE;
	mpos += AES_BLOCK_SIZE;
	}
	if (last) {
	WPA_PUT_BE16(&a[14], i);
	aes_encrypt(aes, a, ppos);
	/* XOR zero-padded last block */
	for (i = 0; i < last; i++)
	ppos++ ^= mpos++;
	}
	wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen);

	/* Authentication */
	/* B_0: Flags \| Nonce N \| l(m) */
	b[0] = 0x40 /* Adata / \| (3 / M' / << 3) \| 1 / L' */;
	os_memcpy(&b[1], nonce, 13);
	WPA_PUT_BE16(&b[14], mlen);

	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
	aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */

	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
	xor_aes_block(aad, x);
	aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */

	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
	AES_BLOCK_SIZE);
	xor_aes_block(&aad[AES_BLOCK_SIZE], x);
	aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
	*/

	ppos = plain;
	for (i = 0; i < mlen / AES_BLOCK_SIZE; i++) {
	/* X_i+1 = E(K, X_i XOR B_i) */
	xor_aes_block(x, ppos);
	ppos += AES_BLOCK_SIZE;
	aes_encrypt(aes, x, x);
	}
	if (last) {
	/* XOR zero-padded last block */
	for (i = 0; i < last; i++)
	x[i] ^= *ppos++;
	aes_encrypt(aes, x, x);
	}

	aes_encrypt_deinit(aes);

	if (os_memcmp(x, t, 8) != 0) {
	u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
	wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame: A1=" MACSTR
	" A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u",
	MAC2STR(hdr->addr1), MAC2STR(hdr->addr2),
	MAC2STR(hdr->addr3),
	WLAN_GET_SEQ_SEQ(seq_ctrl),
	WLAN_GET_SEQ_FRAG(seq_ctrl));
	wpa_hexdump(MSG_DEBUG, "CCMP decrypted", plain, mlen);
	os_free(plain);
	return NULL;
	}

	*decrypted_len = mlen;
	return plain;
	}


	void ccmp_get_pn(u8 pn, const u8 data)
	{
	pn[0] = data[7]; /* PN5 */
	pn[1] = data[6]; /* PN4 */
	pn[2] = data[5]; /* PN3 */
	pn[3] = data[4]; /* PN2 */
	pn[4] = data[1]; /* PN1 */
	pn[5] = data[0]; /* PN0 */
	}


	u8 * ccmp_encrypt(const u8 tk, u8 frame, size_t len, size_t hdrlen, u8 *qos,
	u8 pn, int keyid, size_t encrypted_len)
	{
	u8 aad[2 + 30], nonce[13];
	size_t aad_len;
	u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
	void *aes;
	u8 crypt, pos, ppos, mpos;
	size_t plen, last;
	struct ieee80211_hdr *hdr;
	int i;

	if (len < hdrlen \|\| hdrlen < 24)
	return NULL;
	plen = len - hdrlen;
	last = plen % AES_BLOCK_SIZE;

	crypt = os_malloc(hdrlen + 8 + plen + 8 + AES_BLOCK_SIZE);
	if (crypt == NULL)
	return NULL;

	os_memcpy(crypt, frame, hdrlen);
	hdr = (struct ieee80211_hdr *) crypt;
	hdr->frame_control \|= host_to_le16(WLAN_FC_ISWEP);
	pos = crypt + hdrlen;
	pos++ = pn[5]; / PN0 */
	pos++ = pn[4]; / PN1 */
	pos++ = 0x00; / Rsvd */
	*pos++ = 0x20 \| (keyid << 6);
	pos++ = pn[3]; / PN2 */
	pos++ = pn[2]; / PN3 */
	pos++ = pn[1]; / PN4 */
	pos++ = pn[0]; / PN5 */

	aes = aes_encrypt_init(tk, 16);
	if (aes == NULL) {
	os_free(crypt);
	return NULL;
	}

	os_memset(aad, 0, sizeof(aad));
	ccmp_aad_nonce(hdr, crypt + hdrlen, &aad[2], &aad_len, nonce);
	WPA_PUT_BE16(aad, aad_len);
	wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
	wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);

	/* Authentication */
	/* B_0: Flags \| Nonce N \| l(m) */
	b[0] = 0x40 /* Adata / \| (3 / M' / << 3) \| 1 / L' */;
	os_memcpy(&b[1], nonce, 13);
	WPA_PUT_BE16(&b[14], plen);

	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
	aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */

	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
	xor_aes_block(aad, x);
	aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */

	wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
	AES_BLOCK_SIZE);
	xor_aes_block(&aad[AES_BLOCK_SIZE], x);
	aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
	*/

	ppos = frame + hdrlen;
	for (i = 0; i < plen / AES_BLOCK_SIZE; i++) {
	/* X_i+1 = E(K, X_i XOR B_i) */
	xor_aes_block(x, ppos);
	ppos += AES_BLOCK_SIZE;
	aes_encrypt(aes, x, x);
	}
	if (last) {
	/* XOR zero-padded last block */
	for (i = 0; i < last; i++)
	x[i] ^= *ppos++;
	aes_encrypt(aes, x, x);
	}

	/* Encryption */

	/* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */

	/* A_i = Flags \| Nonce N \| Counter i */
	a[0] = 0x01; /* Flags = L' */
	os_memcpy(&a[1], nonce, 13);

	ppos = crypt + hdrlen + 8;

	/* crypt = msg XOR (S_1 \| S_2 \| ... \| S_n) */
	mpos = frame + hdrlen;
	for (i = 1; i <= plen / AES_BLOCK_SIZE; i++) {
	WPA_PUT_BE16(&a[14], i);
	/* S_i = E(K, A_i) */
	aes_encrypt(aes, a, ppos);
	xor_aes_block(ppos, mpos);
	ppos += AES_BLOCK_SIZE;
	mpos += AES_BLOCK_SIZE;
	}
	if (last) {
	WPA_PUT_BE16(&a[14], i);
	aes_encrypt(aes, a, ppos);
	/* XOR zero-padded last block */
	for (i = 0; i < last; i++)
	ppos++ ^= mpos++;
	}

	wpa_hexdump(MSG_EXCESSIVE, "CCMP T", x, 8);
	/* U = T XOR S_0; S_0 = E(K, A_0) */
	WPA_PUT_BE16(&a[14], 0);
	aes_encrypt(aes, a, b);
	for (i = 0; i < 8; i++)
	ppos[i] = x[i] ^ b[i];
	wpa_hexdump(MSG_EXCESSIVE, "CCMP U", ppos, 8);

	wpa_hexdump(MSG_EXCESSIVE, "CCMP encrypted", crypt + hdrlen + 8, plen);

	aes_encrypt_deinit(aes);

	*encrypted_len = hdrlen + 8 + plen + 8;

	return crypt;
	}