RSA签名与验签

	/**
	 * 测试签名
	 * @throws Exception
	 */
	@Test
	public void testSign() throws Exception {
		byte[] sign = this.sign("Hello World");
		String result = Base64.getEncoder().encodeToString(sign);
		System.out.println(result);
	}
	
	/**
	 * 私钥签名
	 * @param data
	 * @return
	 * @throws Exception
	 */
	private byte[] sign(String data) throws Exception {
		//读取储存的私钥字节数组
		byte[] privateKeyCode = Files.readAllBytes(Paths.get(PRIVATE_KEY_PATH));
		//包装私钥字节数组为一个KeySpec
		PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKeyCode);
		KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
		//通过KeyFactory生成私钥
		PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
		Signature signature = Signature.getInstance("MD5withRSA");//签名的算法
		//通过私钥初始化Signature，签名时用
		signature.initSign(privateKey);
		//指定需要进行签名的内容
		signature.update(data.getBytes());
		//签名
		byte[] result = signature.sign();
		return result;
	}