public static String bytesToHexString(byte[] b) {
		
		if (b == null || b.length < 0) {
			return null;
		}
		
		StringBuilder stringBuilder = new StringBuilder();
		String hv;
		
		for (int i = 0; i < b.length; i++) {
			hv = Integer.toHexString(b[i] & 0xFF);
			
			if (hv.length() < 2) {
				stringBuilder.append(0);
			}
			
			stringBuilder.append(hv);
		}
		
		return stringBuilder.toString();	
	}