A Simple, Portable, Rinjdael (AES) Based Stream Cipher Class

//////////////////////////////////////////////
// Implementation file for DCipher class
//////////////////////////////////////////////


#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif


#include "stdafx.h"
#include "DCipher.h"

/////////////////////////////////////
// Constructors
/////////////////////////////////////

DCipher::DCipher()
{
	//Default Constructor for GetMD5Hash function ONLY
	mp_s8ReadBuffer = 0;
}

DCipher::DCipher(CString szSrc, int head[19])
{
    mp_s8ReadBuffer = 0;

	FileSize=CurPosition=0;
	SrcFile = szSrc;
	szSrc += ".enc";
	OutFile=szSrc;

	for(int i=0; i<19; i++)
	{
		header[i] = head[i];
	}
}

///////////////////////////////////////////
// Destructor
///////////////////////////////////////////
DCipher::~DCipher() 
{
	    FreeBuffer();
};


/////////////////////////////////////
// Implementation
////////////////////////////////////

int DCipher::DecryptFile()
{
	FILE *r, *w;
	int blah = 0;
	int g = 0;
	unsigned int ch;
	GetFileLength();

	if( CheckIfEncrypted() != ENCRYPTED_FILE )
	{
		return ERROR_CANT_DEC;
	}

	if((r = fopen( (LPCTSTR)SrcFile, "rb")) == NULL)
	{
		return ERROR_SRC_FILE;
	}

	if((w = fopen( (LPCTSTR)OutFile, "wb")) == NULL)
	{
		return ERROR_DST_FILE;
	}

	char zzz[25];	//fixed invalid pointer - DKeesler
	fread(zzz, 19, 1, r); // Skip 19 bytes from the file.
	CurPosition=0;

	BuildKey(FALSE);

	/***************************************
	Decryption algorithm 
	***************************************/
	for(long int blk_num=0;;blk_num++)
	{
		for(g=0; g<64; g++)
		{
			CurPosition++;

			if((ch = fgetc(r)) == EOF)
			{
				blah = 1;
				break;
			}

			ch = ~((ch^(blk_num^~g))^(int)password[g]);

			if((ch%2)==0)
			{
				ch-=3;
			}
			else
			{
				ch-=1;
			}

			fputc(ch, w);

		}
			if(blah == 1)
			{
				break;
			}
	}

	fclose(r);
	fclose(w);


	remove((LPCTSTR)SrcFile);
	rename((LPCTSTR)OutFile, (LPCTSTR)SrcFile);

	return NO_ERRORS_DONE;
}

int DCipher::EncryptFile()
{

	FILE *r, *w;
	int blah=0;
	int g=0;
	unsigned int ch;
	GetFileLength();

	if(CheckIfEncrypted() != NORMAL_FILE)
	{
		return ERROR_CANT_ENC;
	}

	if((r = fopen((LPCTSTR)SrcFile, "rb")) == NULL)
	{
		return ERROR_SRC_FILE;
	}

	if((w = fopen((LPCTSTR)OutFile, "wb")) == NULL)
	{
		return ERROR_DST_FILE;
	}

	MarkTheFile(w); // Mark the file.
	CurPosition=0;

	BuildKey(TRUE);

	/***************************************
	Encryption algorithm 
	***************************************/
	for(long int blk_num=0;;blk_num++)
	{
		for(g=0; g<64; g++)
		{
			CurPosition++;
			if((ch=fgetc(r))==EOF)
			{
				blah = 1;
				break;
			}

			if((ch%2)==0)
			{
				ch+=1;
			}
			else
			{
				ch+=3;
			}

			ch =(~ch^(int)password[g])^(blk_num^~g);
			fputc(ch, w);

		}
			if(blah == 1)
			{
				break;
			}
	}
	/***************************************/
	fclose(r);
	fclose(w);

	remove((LPCTSTR)SrcFile);
	rename((LPCTSTR)OutFile, (LPCTSTR)SrcFile);

	return NO_ERRORS_DONE;
}

int DCipher::GetFileLength()
{
	FILE *z = fopen((LPCTSTR)SrcFile, "r");
	long int cur;
	fseek(z, 0L, SEEK_END);
	cur = ftell(z);
	fclose(z);
	FileSize = cur;
	return 0;
}

int DCipher::MarkTheFile(FILE *f)
{
	for(int d=0; d<19; d++)
	fputc(header[d], f);
	return 0;
}


int DCipher::CheckIfEncrypted()
{
	int m[19];
	FILE *h = fopen((LPCTSTR)SrcFile, "rb");
	for(int d=0; d<19; d++)
	m[d] = fgetc(h);
	fclose(h);

	int i = 0;
	do
	{
		if(m[i] != header[i])
			return NORMAL_FILE;
		else
			i++;
	}while(i < 19);

	return ENCRYPTED_FILE;
}



void DCipher::BuildKey(BOOL bEncrypt) //TRUE=encrypt
{

	CString szKey="";
	long int fl = FileSize;
	
	if(!bEncrypt)
		fl -= 19;	//don't count validation bytes if decrypting

	char buf[20];
	_ltoa(fl, buf, 10);
	szKey = buf;

	int sv = szKey.GetLength() / 2;

	_lrotl(fl, sv);

	int mv = atoi(szKey.Right(sv));
	fl *= mv;

	_ltoa(fl, buf, 10);

	CString tmp = buf;

	szKey = CalcMD5FromString((LPCTSTR)tmp, (sv+1)*7);
	
		int l = szKey.GetLength();
		int m = l / 2;
		int j = m+1;
		int d = l-j;

		CString key1;
		CString key2;
		CString key3;
		CString key4;

		key1 = szKey.Left(j);
		key2 = szKey.Right(j);
		key3 = szKey.Mid(d,m);
		key4 = szKey.Right(d);

		szKey = CalcMD5FromString((LPCTSTR)key3, l*3);
		szKey+= CalcMD5FromString((LPCTSTR)key1, l*4);
		szKey+= CalcMD5FromString((LPCTSTR)key4, j*4);
		szKey+= CalcMD5FromString((LPCTSTR)key2, l+m*2);

		strcpy(password, (LPCTSTR)szKey);
}

CString DCipher::GetMD5Hash(CString szKey, int nLen)
{
	CString tmp = szKey;
	szKey = CalcMD5FromString((LPCTSTR)tmp, 20);

		int l = szKey.GetLength();
		int m = l / 2;
		int j = m+1;
		int d = l-j;

		CString key1 = szKey.Right(j);
		CString key2 = szKey.Mid(m-1, m);
		CString key3 = szKey.Left(m);
		CString key4 = szKey.Left(j);

		szKey = CalcMD5FromString((LPCTSTR)key3, l);
	switch (nLen)
	{
	case 256:
		szKey+= CalcMD5FromString((LPCTSTR)key1, l+5);
		break;
	case 512:
		szKey+= CalcMD5FromString((LPCTSTR)key4, l*2);
		szKey+= CalcMD5FromString((LPCTSTR)key2, l+12);
		break;
	}

	return szKey;
}



//////////////////////////////////////////////////////////////////////////
//  BEGIN MD5 HASH SECTION
/////////////////////////////////////////////////////////////////////////

void DCipher::FreeBuffer()
{
    if (mp_s8ReadBuffer) delete mp_s8ReadBuffer;
}

/*********************************************************************
//
//         calculate MD5 from a file of any size (also size = 0)
//         returns "" on file error
//
/********************************************************************/

char* DCipher::CalcMD5FromFile(const char *s8_Path)
{
    if (!mp_s8ReadBuffer) mp_s8ReadBuffer = new char[_ReadBufSize];

    MD5Init();

    // ++++++++++++ Read file block by block +++++++++++

    HANDLE h_File = CreateFile(s8_Path, GENERIC_READ, FILE_SHARE_READ, 0, 
                               OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
        
    if (h_File == INVALID_HANDLE_VALUE)
        return "";

    int s32_Size = GetFileSize(h_File, 0);

    while (s32_Size > 0)
    {
        unsigned long u32_Read = 0;
        if (!ReadFile(h_File, mp_s8ReadBuffer, _ReadBufSize, &u32_Read, 0))
        {
            CloseHandle(h_File);
            return "";
        }

        MD5Update((unsigned char*)mp_s8ReadBuffer, u32_Read);

        s32_Size -= u32_Read;
    };

    CloseHandle(h_File);

    // ++++++++++++ Signature --> String +++++++++++

    return MD5FinalToString();
}


/*********************************************************************
//
//                calculate MD5 from a string
//
/********************************************************************/


char* DCipher::CalcMD5FromString(const char *s8_Input, int nSeedGen)
{
    MD5Init();
    MD5Update((unsigned char*)s8_Input, strlen(s8_Input));

	return MD5ToEncryptionKey(nSeedGen);
}


/*********************************************************************
//
//                           Calculation functions
//
/*********************************************************************
/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void DCipher::MD5Init()
{
    ctx.buf[0] = 0x67452301;
    ctx.buf[1] = 0xefcdab89;
    ctx.buf[2] = 0x98badcfe;
    ctx.buf[3] = 0x10325476;

    ctx.bits[0] = 0;
    ctx.bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void DCipher::MD5Update(unsigned char *buf, unsigned len)
{
    unsigned long t;

    /* Update bitcount */

    t = ctx.bits[0];
    if ((ctx.bits[0] = t + ((unsigned long) len << 3)) < t)
    ctx.bits[1]++;  /* Carry from low to high */
    ctx.bits[1] += len >> 29;

    t = (t >> 3) & 0x3f;    /* Bytes already in shsInfo->data */

    /* Handle any leading odd-sized chunks */

    if (t) {
    unsigned char *p = (unsigned char *) ctx.in + t;

    t = 64 - t;
    if (len < t) {
        memcpy(p, buf, len);
        return;
    }
    memcpy(p, buf, t);
    DCipher::byteReverse(ctx.in, 16);
    MD5Transform(ctx.buf, (unsigned long *) ctx.in);
    buf += t;
    len -= t;
    }
    /* Process data in 64-byte chunks */

    while (len >= 64) {
    memcpy(ctx.in, buf, 64);
    DCipher::byteReverse(ctx.in, 16);
    MD5Transform(ctx.buf, (unsigned long *) ctx.in);
    buf += 64;
    len -= 64;
    }

    /* Handle any remaining bytes of data. */

    memcpy(ctx.in, buf, len);
}


/*
 * Convert signature to CString [from File]
 */
char* DCipher::MD5FinalToString()
{
    unsigned char signature[16];
    MD5Final(signature);

    ms8_MD5[0] = 0;
    char s8_Temp[5];
    for (int i=0; i<16; i++) 
    {
		sprintf(s8_Temp, "%02X", signature[i]);
        strcat(ms8_MD5, s8_Temp);
    }

    return ms8_MD5;
}


/*
 * Convert signature to CString [from String]
 */
char* DCipher::MD5ToEncryptionKey(int nSeed)
{
    unsigned char signature[16];
    MD5Final(signature);

	srand(nSeed);	/////////////// comment lines signify modification to original code
	int val;	///////////////

    ms8_MD5[0] = 0;
    char s8_Temp[5];
    for (int i=0; i<16; i++) 
    {
		val = rand() % 2;	//////////////////////////////////////

		if(val < 1)	//////////////////////////////////////////////
			sprintf(s8_Temp, "%02X", signature[i]);
		else	//////////////////////////////////////////////////
			sprintf(s8_Temp, "%02x", signature[i]);	//////////////

        strcat(ms8_MD5, s8_Temp);
    }

    return ms8_MD5;
}


/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void DCipher::MD5Final(unsigned char digest[16])
{
    unsigned count;
    unsigned char *p;

    /* Compute number of bytes mod 64 */
    count = (ctx.bits[0] >> 3) & 0x3F;

    /* Set the first char of padding to 0x80.  This is safe since there is
       always at least one byte free */
    p = ctx.in + count;
    *p++ = 0x80;

    /* Bytes of padding needed to make 64 bytes */
    count = 64 - 1 - count;

    /* Pad out to 56 mod 64 */
    if (count < 8) {
    /* Two lots of padding:  Pad the first block to 64 bytes */
    memset(p, 0, count);
    DCipher::byteReverse(ctx.in, 16);
    MD5Transform(ctx.buf, (unsigned long *) ctx.in);

    /* Now fill the next block with 56 bytes */
    memset(ctx.in, 0, 56);
    } else {
    /* Pad block to 56 bytes */
    memset(p, 0, count - 8);
    }
    DCipher::byteReverse(ctx.in, 14);

    /* Append length in bits and transform */
    ((unsigned long *) ctx.in)[14] = ctx.bits[0];
    ((unsigned long *) ctx.in)[15] = ctx.bits[1];

    MD5Transform(ctx.buf, (unsigned long *) ctx.in);
    DCipher::byteReverse((unsigned char *) ctx.buf, 4);
    memcpy(digest, ctx.buf, 16);
    memset(&ctx, 0, sizeof(MD5Context));        /* In case it's sensitive */
}


/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
    ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
void DCipher::MD5Transform(unsigned long buf[4], unsigned long in[16])
{
    register unsigned long a, b, c, d;

    a = buf[0];
    b = buf[1];
    c = buf[2];
    d = buf[3];

    MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
    MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
    MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
    MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
    MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
    MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
    MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
    MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
    MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
    MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
    MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
    MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
    MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
    MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
    MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
    MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

    MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
    MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
    MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
    MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
    MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
    MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
    MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
    MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
    MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
    MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
    MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
    MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
    MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
    MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
    MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
    MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

    MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
    MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
    MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
    MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
    MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
    MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
    MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
    MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
    MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
    MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
    MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
    MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
    MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
    MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
    MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
    MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

    MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
    MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
    MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
    MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
    MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
    MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
    MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
    MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
    MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
    MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
    MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
    MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
    MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
    MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
    MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
    MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

    buf[0] += a;
    buf[1] += b;
    buf[2] += c;
    buf[3] += d;
}

#ifdef sgi
#define HIGHFIRST
#endif

#ifdef sun
#define HIGHFIRST
#endif


#ifndef HIGHFIRST
    void DCipher::byteReverse(unsigned char *buf, unsigned longs)  
    {
        // Nothing
    }
#else
    // Note: this code is harmless on little-endian machines.
    void DCipher::byteReverse(unsigned char *buf, unsigned longs)
    {
        unsigned long t;
        do {
        t = (unsigned long) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
            ((unsigned) buf[1] << 8 | buf[0]);
        *(unsigned long *) buf = t;
        buf += 4;
        } while (--longs);
    }
#endif