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/******************************************************************************/
/* File includes */
/* */
#include "airpdcap_system.h"
#include "airpdcap_int.h"
#include "airpdcap_ccmp.h"
#include "airpdcap_rijndael.h"
#include "airpdcap_debug.h"
/* */
/******************************************************************************/
/* Note: this code were copied from FreeBSD source code, RELENG 6, */
/* sys/net80211/ieee80211_crypto_ccmp.c */
/******************************************************************************/
/* Internal definitions */
/* */
#define AES_BLOCK_LEN 16
/* Note: copied from net80211/ieee80211.h */
#define AIRPDCAP_FC1_DIR_MASK 0x03
#define AIRPDCAP_FC1_DIR_DSTODS 0x03 /* AP ->AP */
#define AIRPDCAP_FC0_SUBTYPE_QOS 0x80
#define AIRPDCAP_FC0_TYPE_DATA 0x08
#define AIRPDCAP_FC0_TYPE_MASK 0x0c
#define AIRPDCAP_SEQ_FRAG_MASK 0x000f
#define AIRPDCAP_QOS_HAS_SEQ(wh) \
(((wh)->fc[0] & \
(AIRPDCAP_FC0_TYPE_MASK | AIRPDCAP_FC0_SUBTYPE_QOS)) == \
(AIRPDCAP_FC0_TYPE_DATA | AIRPDCAP_FC0_SUBTYPE_QOS))
/* */
/******************************************************************************/
/******************************************************************************/
/* Internal macros */
/* */
#define CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) { \
/* Decrypt, with counter */ \
_b0[14] = (UINT8)((_i >> 8) & 0xff); \
_b0[15] = (UINT8)(_i & 0xff); \
rijndael_encrypt(&key, _b0, _b); \
xor_block(_pos, _b, _len); \
/* Authentication */ \
xor_block(_a, _pos, _len); \
rijndael_encrypt(&key, _a, _a); \
}
#define AIRPDCAP_ADDR_COPY(dst,src) memcpy(dst,src,AIRPDCAP_MAC_LEN)
/* */
/******************************************************************************/
/******************************************************************************/
/* Internal function prototypes declarations */
/* */
static void ccmp_init_blocks(
rijndael_ctx *ctx,
PAIRPDCAP_MAC_FRAME wh,
UINT64 pn,
size_t dlen,
UINT8 b0[AES_BLOCK_LEN],
UINT8 aad[2 * AES_BLOCK_LEN],
UINT8 a[AES_BLOCK_LEN],
UINT8 b[AES_BLOCK_LEN])
;
/* */
/******************************************************************************/
/******************************************************************************/
/* Function definitions */
/* */
static __inline UINT64 READ_6(
UINT8 b0,
UINT8 b1,
UINT8 b2,
UINT8 b3,
UINT8 b4,
UINT8 b5)
{
UINT32 iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24);
UINT16 iv16 = (UINT16)((b4 << 0) | (b5 << 8));
return (((UINT64)iv16) << 32) | iv32;
}
static void ccmp_init_blocks(
rijndael_ctx *ctx,
PAIRPDCAP_MAC_FRAME wh,
UINT64 pn,
size_t dlen,
UINT8 b0[AES_BLOCK_LEN],
UINT8 aad[2 * AES_BLOCK_LEN],
UINT8 a[AES_BLOCK_LEN],
UINT8 b[AES_BLOCK_LEN])
{
#define IS_4ADDRESS(wh) \
((wh->fc[1] & AIRPDCAP_FC1_DIR_MASK) == AIRPDCAP_FC1_DIR_DSTODS)
#define IS_QOS_DATA(wh) AIRPDCAP_QOS_HAS_SEQ(wh)
memset(aad, 0, 2*AES_BLOCK_LEN);
/* CCM Initial Block:
* Flag (Include authentication header, M=3 (8-octet MIC),
* L=1 (2-octet Dlen))
* Nonce: 0x00 | A2 | PN
* Dlen */
b0[0] = 0x59;
/* NB: b0[1] set below */
AIRPDCAP_ADDR_COPY(b0 + 2, wh->addr2);
b0[8] = (UINT8)(pn >> 40);
b0[9] = (UINT8)(pn >> 32);
b0[10] = (UINT8)(pn >> 24);
b0[11] = (UINT8)(pn >> 16);
b0[12] = (UINT8)(pn >> 8);
b0[13] = (UINT8)(pn >> 0);
b0[14] = (UINT8)((UINT8)(dlen >> 8) & 0xff);
b0[15] = (UINT8)(dlen & 0xff);
/* AAD:
* FC with bits 4..6 and 11..13 masked to zero; 14 is always one
* A1 | A2 | A3
* SC with bits 4..15 (seq#) masked to zero
* A4 (if present)
* QC (if present)
*/
aad[0] = 0; /* AAD length >> 8 */
/* NB: aad[1] set below */
aad[2] = (UINT8)(wh->fc[0] & 0x8f); /* XXX magic #s */
aad[3] = (UINT8)(wh->fc[1] & 0xc7); /* XXX magic #s */
/* NB: we know 3 addresses are contiguous */
memcpy(aad + 4, wh->addr1, 3 * AIRPDCAP_MAC_LEN);
aad[22] = (UINT8)(wh->seq[0] & AIRPDCAP_SEQ_FRAG_MASK);
aad[23] = 0; /* all bits masked */
/*
* Construct variable-length portion of AAD based
* on whether this is a 4-address frame/QOS frame.
* We always zero-pad to 32 bytes before running it
* through the cipher.
*
* We also fill in the priority bits of the CCM
* initial block as we know whether or not we have
* a QOS frame.
*/
if (IS_4ADDRESS(wh)) {
AIRPDCAP_ADDR_COPY(aad + 24,
((PAIRPDCAP_MAC_FRAME_ADDR4)wh)->addr4);
if (IS_QOS_DATA(wh)) {
PAIRPDCAP_MAC_FRAME_ADDR4_QOS qwh4 =
(PAIRPDCAP_MAC_FRAME_ADDR4_QOS) wh;
aad[30] = (UINT8)(qwh4->qos[0] & 0x0f);/* just priority bits */
aad[31] = 0;
b0[1] = aad[30];
aad[1] = 22 + AIRPDCAP_MAC_LEN + 2;
} else {
*(UINT16 *)&aad[30] = 0;
b0[1] = 0;
aad[1] = 22 + AIRPDCAP_MAC_LEN;
}
} else {
if (IS_QOS_DATA(wh)) {
PAIRPDCAP_MAC_FRAME_QOS qwh =
(PAIRPDCAP_MAC_FRAME_QOS) wh;
aad[24] = (UINT8)(qwh->qos[0] & 0x0f); /* just priority bits */
aad[25] = 0;
b0[1] = aad[24];
aad[1] = 22 + 2;
} else {
*(UINT16 *)&aad[24] = 0;
b0[1] = 0;
aad[1] = 22;
}
*(UINT16 *)&aad[26] = 0;
*(UINT16 *)&aad[28] = 0;
}
/* Start with the first block and AAD */
rijndael_encrypt(ctx, b0, a);
xor_block(a, aad, AES_BLOCK_LEN);
rijndael_encrypt(ctx, a, a);
xor_block(a, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
rijndael_encrypt(ctx, a, a);
b0[0] &= 0x07;
b0[14] = b0[15] = 0;
rijndael_encrypt(ctx, b0, b);
//XOR( m + len - 8, b, 8 );
#undef IS_QOS_DATA
#undef IS_4ADDRESS
}
INT AirPDcapCcmpDecrypt(
UINT8 *m,
INT len,
UCHAR TK1[16])
{
PAIRPDCAP_MAC_FRAME wh;
UINT8 aad[2 * AES_BLOCK_LEN];
UINT8 b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
UINT8 mic[AES_BLOCK_LEN];
size_t data_len;
UINT i;
UINT8 *pos;
UINT space;
INT z=AIRPDCAP_HEADER_LEN(m[1]);
rijndael_ctx key;
UCHAR PN[6];
UINT64 tPN;
UINT8 *ivp=m+z;
tPN = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
memcpy(PN, &tPN, 6);
/* freebsd */
rijndael_set_key(&key, TK1, 128);
wh = (PAIRPDCAP_MAC_FRAME )m;
data_len = len - (z + AIRPDCAP_CCMP_HEADER+AIRPDCAP_CCMP_TRAILER);
ccmp_init_blocks(&key, wh, *(UINT64 *)PN, data_len, b0, aad, a, b);
memcpy(mic, m+len-AIRPDCAP_CCMP_TRAILER, AIRPDCAP_CCMP_TRAILER);
xor_block(mic, b, AIRPDCAP_CCMP_TRAILER);
i = 1;
pos = (UINT8 *)m + z + AIRPDCAP_CCMP_HEADER;
space = len - (z + AIRPDCAP_CCMP_HEADER);
if (space > data_len)
space = (UINT)data_len;
while (space >= AES_BLOCK_LEN) {
CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN);
pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
data_len -= AES_BLOCK_LEN;
i++;
}
if (space != 0) /* short last block */
CCMP_DECRYPT(i, b, b0, pos, a, space);
/* MIC Key ?= MIC */
if (memcmp(mic, a, AIRPDCAP_CCMP_TRAILER) == 0) {
return 0;
}
/* TODO replay check (IEEE 802.11i-2004, pg. 62) */
/* TODO PN must be incremental (IEEE 802.11i-2004, pg. 62) */
return 1;
}
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