Loop issue

void CCrypt::EnCrypt( unsigned char* buffer, unsigned size )
{
	// check data correctness
	if ( !buffer )
		return;
	if ( size < 4 )
		return;

	unsigned char * encBuffer = new unsigned char[ size + 4 ];

	unsigned m = size + 4;

	// copy data from the encBuffer to Buffer  
	memcpy( encBuffer, buffer + 4, sizeof( unsigned char ) * m );

	const char unknown_key[] = "qmfaktnpgjs";
        unsigned char unknown_key2[sizeof(unknown_key)];
        std::copy(unknown_key, unknown_key + sizeof(unknown_key), unknown_key2);

	if ( encBuffer == NULL)
		return;
        if ( m < 4 )
		return;

	// perform header encrypting
	encBuffer[ 0 ] = m & 0xFF;
	encBuffer[ 1 ] = ( m & 0xFF00 ) >> 8;
	encBuffer[ 2 ] = 0x01;
	encBuffer[ 3 ] = 0x00;
	for (unsigned i = 4; i < m; i++)
	{
		if ( encBuffer[i] != 0)
		{
			encBuffer[ i ] = unknown_key2[i % 0xB] ^ encBuffer[ i ];
		}
	}
	// swap buffers
	delete [] buffer;
	buffer = encBuffer;
	size = m;
}

01 c2 eb 0b 00 11 08 01 00 00 00 00 00 01 00 46 61 63 65 6f 66 44 65 76 69 6c 00 00 00 00 00 00 00 00 00 00 00 00 00

2b 00 01 00 70 af 8d 6a  00 65 66 71 00 00 00 00 
00 67 00 2d 15 0d 15 08  0c 37 14 1b 0f 0d 00 00 
00 00 00 00 00 00 00 00  00 00 00