Calculate MD5 Hash in Kernel Mode

// MD5.H

#ifndef _MD5_H
#define _MD5_H

/***********************************************************************
* Function Name: MD5File
* Function Description: Calculates the MD5 value of file
* Parameter List:
* PStrFileName: filename
* PStrFileMD5: get the MD5
* Return Value: NTSTATUS
* Note:
* PStrFileName should be the complete path, use symbolic links or device name
* Such as "C: \\ 1.txt" should be "\\ ?? \\ C: \\ 1.txt" or "\\ Device \\ HarddiskVolume1 \\ 1.txt"
* PStrFileMD5 responsible for memory allocation from the outside
***********************************************************************/
NTSTATUS
MD5File(IN PUNICODE_STRING pStrFileName, OUT PUNICODE_STRING pStrFileMD5);

/***********************************************************************
* Function Name: MD5String
* Function Description: Calculates the MD5 string values
* Parameter List:
* PStr: String
* PStrMD5: calculated MD5
* Return Value: NTSTATUS
* PStrFileMD5 responsible for memory allocation from the outside
***********************************************************************/
NTSTATUS
MD5String(IN PUNICODE_STRING pStr, OUT PUNICODE_STRING pStrMD5);

#endif

#include <NTDDK.h>
#include <Ntstrsafe.h>
#include "md5.h"

#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

#define RL(x, y) (((x) << (y)) | ((x) >> (32 - (y))))  //x y bit left cyclic shift

#define PP(x) (x<<24)|((x<<8)&0xff0000)|((x>>8)&0xff00)|(x>>24)  //The x height position swaps, for example, PP(aabbccdd)=ddccbbaa

#define FF(a, b, c, d, x, s, ac) a = b + (RL((a + F(b,c,d) + x + ac),s))
#define GG(a, b, c, d, x, s, ac) a = b + (RL((a + G(b,c,d) + x + ac),s))
#define HH(a, b, c, d, x, s, ac) a = b + (RL((a + H(b,c,d) + x + ac),s))
#define II(a, b, c, d, x, s, ac) a = b + (RL((a + I(b,c,d) + x + ac),s))

unsigned int A, B, C, D, x[16];
/***********************************************************************
* Function Name: MD5Calc
* Function Description: MD5 core algorithm for 64
* Parameter List: Empty
* Return Value: None
***********************************************************************/
void MD5Calc(){
unsigned a, b, c, d;
a = A, b = B, c = C, d = D;
/* Round 1 */
FF(a, b, c, d, x[0], 7, 0xd76aa478); /* 1 */
FF(d, a, b, c, x[1], 12, 0xe8c7b756); /* 2 */
FF(c, d, a, b, x[2], 17, 0x242070db); /* 3 */
FF(b, c, d, a, x[3], 22, 0xc1bdceee); /* 4 */
FF(a, b, c, d, x[4], 7, 0xf57c0faf); /* 5 */
FF(d, a, b, c, x[5], 12, 0x4787c62a); /* 6 */
FF(c, d, a, b, x[6], 17, 0xa8304613); /* 7 */
FF(b, c, d, a, x[7], 22, 0xfd469501); /* 8 */
FF(a, b, c, d, x[8], 7, 0x698098d8); /* 9 */
FF(d, a, b, c, x[9], 12, 0x8b44f7af); /* 10 */
FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
FF(a, b, c, d, x[12], 7, 0x6b901122); /* 13 */
FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

/* Round 2 */
GG(a, b, c, d, x[1], 5, 0xf61e2562); /* 17 */
GG(d, a, b, c, x[6], 9, 0xc040b340); /* 18 */
GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
GG(b, c, d, a, x[0], 20, 0xe9b6c7aa); /* 20 */
GG(a, b, c, d, x[5], 5, 0xd62f105d); /* 21 */
GG(d, a, b, c, x[10], 9, 0x02441453); /* 22 */
GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
GG(b, c, d, a, x[4], 20, 0xe7d3fbc8); /* 24 */
GG(a, b, c, d, x[9], 5, 0x21e1cde6); /* 25 */
GG(d, a, b, c, x[14], 9, 0xc33707d6); /* 26 */
GG(c, d, a, b, x[3], 14, 0xf4d50d87); /* 27 */
GG(b, c, d, a, x[8], 20, 0x455a14ed); /* 28 */
GG(a, b, c, d, x[13], 5, 0xa9e3e905); /* 29 */
GG(d, a, b, c, x[2], 9, 0xfcefa3f8); /* 30 */
GG(c, d, a, b, x[7], 14, 0x676f02d9); /* 31 */
GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

/* Round 3 */
HH(a, b, c, d, x[5], 4, 0xfffa3942); /* 33 */
HH(d, a, b, c, x[8], 11, 0x8771f681); /* 34 */
HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
HH(a, b, c, d, x[1], 4, 0xa4beea44); /* 37 */
HH(d, a, b, c, x[4], 11, 0x4bdecfa9); /* 38 */
HH(c, d, a, b, x[7], 16, 0xf6bb4b60); /* 39 */
HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
HH(a, b, c, d, x[13], 4, 0x289b7ec6); /* 41 */
HH(d, a, b, c, x[0], 11, 0xeaa127fa); /* 42 */
HH(c, d, a, b, x[3], 16, 0xd4ef3085); /* 43 */
HH(b, c, d, a, x[6], 23, 0x04881d05); /* 44 */
HH(a, b, c, d, x[9], 4, 0xd9d4d039); /* 45 */
HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
HH(b, c, d, a, x[2], 23, 0xc4ac5665); /* 48 */

/* Round 4 */
II(a, b, c, d, x[0], 6, 0xf4292244); /* 49 */
II(d, a, b, c, x[7], 10, 0x432aff97); /* 50 */
II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
II(b, c, d, a, x[5], 21, 0xfc93a039); /* 52 */
II(a, b, c, d, x[12], 6, 0x655b59c3); /* 53 */
II(d, a, b, c, x[3], 10, 0x8f0ccc92); /* 54 */
II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
II(b, c, d, a, x[1], 21, 0x85845dd1); /* 56 */
II(a, b, c, d, x[8], 6, 0x6fa87e4f); /* 57 */
II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
II(c, d, a, b, x[6], 15, 0xa3014314); /* 59 */
II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
II(a, b, c, d, x[4], 6, 0xf7537e82); /* 61 */
II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
II(c, d, a, b, x[2], 15, 0x2ad7d2bb); /* 63 */
II(b, c, d, a, x[9], 21, 0xeb86d391); /* 64 */
A += a;
B += b;
C += c;
D += d;
}

/***********************************************************************
* Function name: MD5 File
* Function Description: Calculates the MD5 value of file
* Parameter List:
* PStrFileName: filename
* PStrFileMD5: get the MD5
* Return Value: NTSTATUS
* Note:
* PStrFileName should be the complete path, use symbolic links or device name
* Such as "C: \\ 1.txt" should be "\\ ?? \\ C: \\ 1.txt" or "\\ Device \\ HarddiskVolume1 \\ 1.txt"
* PStrFileMD5 responsible for memory allocation from the outside
***********************************************************************/
NTSTATUS
MD5File(IN PUNICODE_STRING pStrFileName, OUT PUNICODE_STRING pStrFileMD5)
{
// Make sure pStrFileMD5 space large enough and cleared
if (pStrFileMD5->MaximumLength < 32 * 2)
return STATUS_BUFFER_TOO_SMALL;
pStrFileMD5->Length = 0;
memset(pStrFileMD5->Buffer, 0, pStrFileMD5->MaximumLength);

// First determines whether a file exists
NTSTATUS status = STATUS_SUCCESS;
HANDLE hFile;
OBJECT_ATTRIBUTES objAttributes;
IO_STATUS_BLOCK ioStatus;
InitializeObjectAttributes(&objAttributes,
pStrFileName,
OBJ_CASE_INSENSITIVE,
NULL,
NULL);
status = ZwCreateFile(&hFile,
GENERIC_READ,
&objAttributes,
&ioStatus,
NULL,
FILE_ATTRIBUTE_NORMAL,
FILE_SHARE_READ,
FILE_OPEN,
FILE_SYNCHRONOUS_IO_NONALERT,
NULL,
0);

if (!NT_SUCCESS(status))
{
// File does not exist
//	KdPrint(("MD5File - File \"%wZ\" DONT Exist\n",pStrFileName));
return status;
}

// Read the file length
unsigned int i, len, flen[2];   //i temporary variable, len file length, flen [2] for the 64-bit file original length binary representation
FILE_STANDARD_INFORMATION fsi;
status = ZwQueryInformationFile(hFile,
&ioStatus,
&fsi,
sizeof(FILE_STANDARD_INFORMATION),
FileStandardInformation);
if (!NT_SUCCESS(status))
{
//Failed to get the file length
//	KdPrint(("MD5File - GetFileLength \"%wZ\" Error\n",pStrFileName));
return status;
}
len = fsi.EndOfFile.LowPart;
flen[1] = len / 0x20000000;     //flen unit is bit
flen[0] = (len % 0x20000000) * 8;

// Set the file pointer to start
FILE_POSITION_INFORMATION fpi;
fpi.CurrentByteOffset.QuadPart = 0i64;
status = ZwSetInformationFile(hFile,
&ioStatus,
&fpi,
sizeof(FILE_POSITION_INFORMATION),
FilePositionInformation);
ASSERT(status == STATUS_SUCCESS);

//Reads the file and calculate the MD5
A = 0x67452301, B = 0xefcdab89, C = 0x98badcfe, D = 0x10325476; //Link variable initialization
RtlFillMemory(&x, 64, 0);
ZwReadFile(hFile, NULL, NULL, NULL, &ioStatus, &x, 64, NULL, NULL);
for (i = 0; i < len / 64; i++)
{	//End loop operation until the file
MD5Calc();
RtlFillMemory(&x, 64, 0);
ZwReadFile(hFile, NULL, NULL, NULL, &ioStatus, &x, 64, NULL, NULL);
}
((char*)x)[len % 64] = 0x80;  // Make an end of file, fill 0 operation, 0x80 binary that is 10000000
if (len % 64 > 55)
{
MD5Calc();
RtlFillMemory(&x, 64, 0);
}
RtlCopyMemory(x + 14, flen, 8);//Files added at the end of the bit length of the original document
MD5Calc();

//Write strMD5
//	KdPrint(("MD5File - File \"%wZ\" MD5 Code:%08x%08x%08x%08x\n",pStrFileName,PP(A),PP(B),PP(C),PP(D)));
status = RtlStringCchPrintfW(pStrFileMD5->Buffer, 33, L"%08x%08x%08x%08x", PP(A), PP(B), PP(C), PP(D));	//High and low reverse output
ASSERT(status == STATUS_SUCCESS);
pStrFileMD5->Length = 32 * 2;

// Close file
ZwClose(hFile);

return status;
}

/***********************************************************************
* Function Name: MD5String
* Function Description: Calculates the MD5 string values
* Parameter List:
* PStr: String
* PStrMD5: calculated MD5
* Return Value: NTSTATUS
* PStrFileMD5 responsible for memory allocation from the outside
***********************************************************************/
NTSTATUS
MD5String(IN PUNICODE_STRING pStr, OUT PUNICODE_STRING pStrMD5)
{
//Ensure pStrFileMD5 space is large enough, and cleared
if (pStrMD5->MaximumLength < 32 * 2)
return STATUS_BUFFER_TOO_SMALL;
pStrMD5->Length = 0;
memset(pStrMD5->Buffer, 0, pStrMD5->MaximumLength);

// Storage MD5
//	UNICODE_STRING strMD5;
//	WCHAR strMD5Buf[33];
//	RtlInitEmptyUnicodeString(&strMD5,strMD5Buf,sizeof(strMD5Buf));
unsigned int i, len, flen[2];   //i temporary variable, len string length, flen [2] for the 64 original length binary representation
len = pStr->Length;
flen[1] = len / 0x20000000;     //flen unit is bit
flen[0] = (len % 0x20000000) * 8;

// Reads the file and calculate the MD5
A = 0x67452301, B = 0xefcdab89, C = 0x98badcfe, D = 0x10325476; //Link variable initialization
RtlFillMemory(&x, 64, 0);
RtlCopyMemory(x, pStr->Buffer, 64);

for (i = 0; i < len / 64; i++)
{	//End loop operation until the file
MD5Calc();
RtlFillMemory(&x, 64, 0);
RtlCopyMemory(x, pStr->Buffer, 64);
}
((char*)x)[len % 64] = 0x80;  //File end up 1 0s operation, 0x80 binary that is 10000000
if (len % 64 > 55)
{
MD5Calc();
RtlFillMemory(&x, 64, 0);
}
RtlCopyMemory(x + 14, flen, 8);//Files added at the end of the bit length of the original document
MD5Calc();

//Write strMD5
//	KdPrint(("MD5String - String \"%wZ\" MD5 Code:%08x%08x%08x%08x\n",pStr,PP(A),PP(B),PP(C),PP(D)));
RtlStringCchPrintfW(pStrMD5->Buffer, 33, L"%08x%08x%08x%08x", PP(A), PP(B), PP(C), PP(D));	// High and low reverse output
pStrMD5->Length = 32 * 2;

return STATUS_SUCCESS;
}

UNICODE_STRING usFilePath;
RtlInitUnicodeString(&usFilePath, L"\\??\\C:\\psfile.exe");
UNICODE_STRING usFileMD5;
WCHAR usFileMD5Buf[0x200];
RtlInitEmptyUnicodeString(&usFileMD5, usFileMD5Buf, sizeof(usFileMD5Buf));

NTSTATUS status111 = MD5File(&usFilePath, &usFileMD5);
/*if (NT_SUCCESS(status))
{*/
DbgPrint("FilePath = %wZ,usFileMD5 = %wZ\n", &usFilePath, &usFileMD5);
/*	break;
}*/