public static PrivateKey decryptPrivateKeyFile()
	{
		File encryptedFile = new File ("EncPrivKey.txt");
		byte[] eprivateKeyBytes = Decryption.readFromFile(encryptedFile);
		byte[] clearText=null;
		
		//decrypt privateKeyBytes
		Cipher aes;
		try {
			aes = Cipher.getInstance("AES/ECB/PKCS5Padding");
			aes.init(Cipher.DECRYPT_MODE, SellerBackEnd.getSymmetricKey());
			clearText = aes.doFinal(eprivateKeyBytes);
			} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
				System.out.println("Error in decryptByteArray");
				e.printStackTrace();
			}
		//convert from byte[] to privateKey
		PrivateKey privateKey= null;
		try {
			privateKey = KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(clearText));
		} catch (InvalidKeySpecException | NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return privateKey;
	}