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/*
* Driver for KeyStream wireless LAN
*
* Copyright (C) 2005-2008 KeyStream Corp.
* Copyright (C) 2009 Renesas Technology Corp.
*
* 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.
*/
#include <linux/types.h>
#include <linux/string.h>
#include "michael_mic.h"
// Rotation functions on 32 bit values
#define ROL32( A, n ) ( ((A) << (n)) | ( ((A)>>(32-(n))) & ( (1UL << (n)) - 1 ) ) )
#define ROR32( A, n ) ROL32( (A), 32-(n) )
// Convert from Byte[] to UInt32 in a portable way
#define getUInt32( A, B ) (uint32_t)(A[B+0] << 0) + (A[B+1] << 8) + (A[B+2] << 16) + (A[B+3] << 24)
// Convert from UInt32 to Byte[] in a portable way
#define putUInt32(A, B, C) \
do { \
A[B + 0] = (uint8_t)(C & 0xff); \
A[B + 1] = (uint8_t)((C >> 8) & 0xff); \
A[B + 2] = (uint8_t)((C >> 16) & 0xff); \
A[B + 3] = (uint8_t)((C >> 24) & 0xff); \
} while (0)
// Reset the state to the empty message.
#define MichaelClear(A) \
do { \
A->L = A->K0; \
A->R = A->K1; \
A->nBytesInM = 0; \
} while (0)
static
void MichaelInitializeFunction(struct michel_mic_t *Mic, uint8_t *key)
{
// Set the key
Mic->K0 = getUInt32(key, 0);
Mic->K1 = getUInt32(key, 4);
//clear();
MichaelClear(Mic);
}
#define MichaelBlockFunction(L, R) \
do{ \
R ^= ROL32( L, 17 ); \
L += R; \
R ^= ((L & 0xff00ff00) >> 8) | ((L & 0x00ff00ff) << 8); \
L += R; \
R ^= ROL32( L, 3 ); \
L += R; \
R ^= ROR32( L, 2 ); \
L += R; \
}while(0)
static
void MichaelAppend(struct michel_mic_t *Mic, uint8_t *src, int nBytes)
{
int addlen;
if (Mic->nBytesInM) {
addlen = 4 - Mic->nBytesInM;
if (addlen > nBytes)
addlen = nBytes;
memcpy(&Mic->M[Mic->nBytesInM], src, addlen);
Mic->nBytesInM += addlen;
src += addlen;
nBytes -= addlen;
if (Mic->nBytesInM < 4)
return;
Mic->L ^= getUInt32(Mic->M, 0);
MichaelBlockFunction(Mic->L, Mic->R);
Mic->nBytesInM = 0;
}
while (nBytes >= 4) {
Mic->L ^= getUInt32(src, 0);
MichaelBlockFunction(Mic->L, Mic->R);
src += 4;
nBytes -= 4;
}
if (nBytes > 0) {
Mic->nBytesInM = nBytes;
memcpy(Mic->M, src, nBytes);
}
}
static
void MichaelGetMIC(struct michel_mic_t *Mic, uint8_t *dst)
{
uint8_t *data = Mic->M;
switch (Mic->nBytesInM) {
case 0:
Mic->L ^= 0x5a;
break;
case 1:
Mic->L ^= data[0] | 0x5a00;
break;
case 2:
Mic->L ^= data[0] | (data[1] << 8) | 0x5a0000;
break;
case 3:
Mic->L ^= data[0] | (data[1] << 8) | (data[2] << 16) |
0x5a000000;
break;
}
MichaelBlockFunction(Mic->L, Mic->R);
MichaelBlockFunction(Mic->L, Mic->R);
// The appendByte function has already computed the result.
putUInt32(dst, 0, Mic->L);
putUInt32(dst, 4, Mic->R);
// Reset to the empty message.
MichaelClear(Mic);
}
void MichaelMICFunction(struct michel_mic_t *Mic, uint8_t *Key,
uint8_t *Data, int Len, uint8_t priority,
uint8_t *Result)
{
uint8_t pad_data[4] = { priority, 0, 0, 0 };
// Compute the MIC value
/*
* IEEE802.11i page 47
* Figure 43g TKIP MIC processing format
* +--+--+--------+--+----+--+--+--+--+--+--+--+--+
* |6 |6 |1 |3 |M |1 |1 |1 |1 |1 |1 |1 |1 | Octet
* +--+--+--------+--+----+--+--+--+--+--+--+--+--+
* |DA|SA|Priority|0 |Data|M0|M1|M2|M3|M4|M5|M6|M7|
* +--+--+--------+--+----+--+--+--+--+--+--+--+--+
*/
MichaelInitializeFunction(Mic, Key);
MichaelAppend(Mic, (uint8_t *) Data, 12); /* |DA|SA| */
MichaelAppend(Mic, pad_data, 4); /* |Priority|0|0|0| */
MichaelAppend(Mic, (uint8_t *) (Data + 12), Len - 12); /* |Data| */
MichaelGetMIC(Mic, Result);
}
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