Sample Code
Windows Driver Samples/ Native Wi-Fi Miniport Sample Driver/ C++/ hw/ hw_crypto.c/
/*++
Copyright (c) Microsoft Corporation. All rights reserved.
Module Name:
hw_crypto.c
Abstract:
Implements the cipher/encryption functionality for the HW layer
Revision History:
When What
---------- ----------------------------------------------
09-04-2007 Created
Notes:
--*/
#include "precomp.h"
#include "hw_crypto.h"
#if DOT11_TRACE_ENABLED
#include "hw_crypto.tmh"
#endif
#define ROL32(A,n) ((A << n) | ((A >> (32 - n)) & ((1UL << n) - 1)))
#define ROR32(A,n) ROL32(A, (32 - n))
__inline
VOID
HwMICBlock(
PULONG L,
PULONG R
)
{
*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;
}
NDIS_STATUS
HwCalculateTxMIC(
_In_ PNET_BUFFER NetBuffer,
_In_ UCHAR Priority,
_In_reads_bytes_(8) PUCHAR MICKey,
_Out_writes_bytes_(HW_MIC_LENGTH) PUCHAR MICData
)
{
ULONG L, R;
ULONG length;
PMDL mdl;
ULONG offset;
PUCHAR bytePtr;
ULONG index;
ULONG count;
ULONG dataSize;
ULONG data;
PUCHAR SA;
PUCHAR DA;
ULONG headerSize;
PDOT11_DATA_LONG_HEADER dataHeader;
//
// Note: only the first MDL is guaranteed to be mapped to system virtual space.
//
//
// Find data header.
//
mdl = NET_BUFFER_CURRENT_MDL(NetBuffer);
dataHeader = Add2Ptr(mdl->MappedSystemVa, NET_BUFFER_CURRENT_MDL_OFFSET(NetBuffer));
//
// Find SA, DA and header size.
//
if (dataHeader->FrameControl.ToDS)
{
DA = dataHeader->Address3;
if (dataHeader->FrameControl.FromDS)
{
headerSize = sizeof(DOT11_DATA_LONG_HEADER);
SA = dataHeader->Address4;
}
else
{
headerSize = sizeof(DOT11_DATA_SHORT_HEADER);
SA = dataHeader->Address2;
}
}
else
{
headerSize = sizeof(DOT11_DATA_SHORT_HEADER);
DA = dataHeader->Address1;
if (dataHeader->FrameControl.FromDS)
{
SA = dataHeader->Address3;
}
else
{
SA = dataHeader->Address2;
}
}
//
// Find the size of data the MIC is calculated on.
//
dataSize = NET_BUFFER_DATA_LENGTH(NetBuffer) - headerSize;
length = 16 + dataSize + 5; // MSDU + 5 bytes pad (one 0x5a, four 0s)
if (length & 0x03)
{
length += 4 - (length & 0x03); // extra 0-3 bytes of 0s pad
}
length >>= 2;
//
// Find the starting offset for actual data (payload).
// Caller guarantees that the header is in one single MDL.
//
offset = NET_BUFFER_CURRENT_MDL_OFFSET(NetBuffer) + headerSize;
ASSERT(offset <= mdl->ByteCount);
bytePtr = Add2Ptr(mdl->MappedSystemVa, offset);
//
// Initial L and R value from MIC key.
//
L = *((ULONG UNALIGNED *)MICKey);
R = *((ULONG UNALIGNED *)(MICKey + 4));
//
// Loop to calculate the MIC
//
for (index = 0; index < length - 1; index++)
{
switch (index)
{
case 0:
data = *((ULONG UNALIGNED *)DA);
break;
case 1:
data = *((USHORT UNALIGNED *)SA);
data <<= 16;
data |= *((USHORT UNALIGNED *)(DA + 4));
break;
case 2:
data = *((ULONG UNALIGNED *)(SA + 2));
break;
case 3:
data = Priority;
break;
default:
//
// Data
//
if (offset + 4 <= mdl->ByteCount && (index - 4) * 4 + 4 <= dataSize)
{
//
// We can get the whole ULONG in contiguous virtual memory.
//
data = *((ULONG UNALIGNED *)bytePtr);
bytePtr += 4;
offset += 4;
}
else
{
//
// We can't get the whole ULONG in contiguous virtual memory.
// Get one byte at a time.
//
count = 0;
data = 0;
while (count < 4)
{
ASSERT((index - 4) * 4 + count <= dataSize);
if ((index - 4) * 4 + count == dataSize)
{
//
// We are done reading. Append 0x5a at the end.
//
data |= 0x5a << (count * 8);
break;
}
else if (offset < mdl->ByteCount)
{
//
// We can get the next byte without going to next MDL
//
data |= ((ULONG)(*bytePtr)) << (count * 8);
bytePtr++;
offset++;
count++;
}
else
{
//
// We are at the end of a MDL. Follow the link to
// traverse to the next MDL.
//
mdl = mdl->Next;
ASSERT(mdl);
//
// Map the new MDL to system virtual space.
//
bytePtr = NdisBufferVirtualAddressSafe(mdl, NormalPagePriority);
if (!bytePtr)
{
return NDIS_STATUS_RESOURCES;
}
offset = 0;
}
}
}
}
L ^= data;
HwMICBlock(&L, &R);
}
HwMICBlock(&L, &R);
*((ULONG UNALIGNED *)MICData) = L;
*((ULONG UNALIGNED *)(MICData + 4)) = R;
return NDIS_STATUS_SUCCESS;
}
NDIS_STATUS
HwCalculateRxMIC(
_In_ PHW_RX_MSDU Msdu,
_In_ UCHAR Priority,
_In_reads_bytes_(8) PUCHAR MICKey,
_Out_writes_bytes_(HW_MIC_LENGTH) PUCHAR MICData
)
{
ULONG L, R;
ULONG length;
ULONG offset;
PUCHAR bytePtr;
ULONG index;
ULONG count;
ULONG dataSize;
ULONG data;
PUCHAR SA;
PUCHAR DA;
ULONG headerSize;
PDOT11_DATA_LONG_HEADER dataHeader;
PHW_RX_MPDU mpdu;
USHORT mpduIndex = 0;
//
// Find data header.
//
mpdu = Msdu->MpduList[0];
dataHeader = (PDOT11_DATA_LONG_HEADER)mpdu->DataStart;
//
// Find SA, DA and header size.
//
if (dataHeader->FrameControl.ToDS)
{
DA = dataHeader->Address3;
if (dataHeader->FrameControl.FromDS)
{
headerSize = sizeof(DOT11_DATA_LONG_HEADER);
SA = dataHeader->Address4;
}
else
{
headerSize = sizeof(DOT11_DATA_SHORT_HEADER);
SA = dataHeader->Address2;
}
}
else
{
headerSize = sizeof(DOT11_DATA_SHORT_HEADER);
DA = dataHeader->Address1;
if (dataHeader->FrameControl.FromDS)
{
SA = dataHeader->Address3;
}
else
{
SA = dataHeader->Address2;
}
}
//
// Find the size of data the MIC is calculated on.
//
dataSize = Msdu->DataLength - headerSize;
length = 16 + dataSize + 5; // MSDU + 5 bytes pad (one 0x5a, four 0s)
if (length & 0x03)
{
length += 4 - (length & 0x03); // extra 0-3 bytes of 0s pad
}
length >>= 2;
//
// Find the starting offset for actual data (payload).
// Caller guarantees that the header is in one single MDL.
//
offset = headerSize;
MPASSERT(offset <= mpdu->DataLength);
bytePtr = mpdu->DataStart + offset;
//
// Initial L and R value from MIC key.
//
L = *((ULONG UNALIGNED *)MICKey);
R = *((ULONG UNALIGNED *)(MICKey + 4));
//
// Loop to calculate the MIC
//
for (index = 0; index < length - 1; index++)
{
switch (index)
{
case 0:
data = *((ULONG UNALIGNED *)DA);
break;
case 1:
data = *((USHORT UNALIGNED *)SA);
data <<= 16;
data |= *((USHORT UNALIGNED *)(DA + 4));
break;
case 2:
data = *((ULONG UNALIGNED *)(SA + 2));
break;
case 3:
data = Priority;
break;
default:
//
// Data
//
if (offset + 4 <= mpdu->DataLength && (index - 4) * 4 + 4 <= dataSize)
{
//
// We can get the whole ULONG in contiguous virtual memory.
//
data = *((ULONG UNALIGNED *)bytePtr);
bytePtr += 4;
offset += 4;
}
else
{
//
// We can't get the whole ULONG in contiguous virtual memory.
// Get one byte at a time.
//
count = 0;
data = 0;
while (count < 4)
{
ASSERT((index - 4) * 4 + count <= dataSize);
if ((index - 4) * 4 + count == dataSize)
{
//
// We are done reading. Append 0x5a at the end.
//
data |= 0x5a << (count * 8);
break;
}
else if (offset < mpdu->DataLength)
{
//
// We can get the next byte without going to next MPDU
//
data |= ((ULONG)(*bytePtr)) << (count * 8);
bytePtr++;
offset++;
count++;
}
else
{
//
// We are at the end of a MPDU. Get the next
// MPDU
//
mpduIndex++;
if (mpduIndex < Msdu->MpduCount)
{
mpdu = Msdu->MpduList[mpduIndex];
bytePtr = mpdu->DataStart;
offset = 0;
}
else
{
// Failed
MPASSERT(FALSE);
break;
}
}
}
}
}
L ^= data;
HwMICBlock(&L, &R);
}
HwMICBlock(&L, &R);
*((ULONG UNALIGNED *)MICData) = L;
*((ULONG UNALIGNED *)(MICData + 4)) = R;
return NDIS_STATUS_SUCCESS;
}
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