RSA算法解密 javax.crypto.BadPaddingException: Decryption error 异常

背景

最近需要对接京东的一个会员管家嵌入到小程序当中，在进行接口请求时，需要对敏感的字段进行RSA加密处理，所以想写一个工具类方便调用。
生成秘钥、加密明文都没问题，就是在解密的时候时候出现了一下异常：

原因

在使用公钥加密的时候，最后我用了Base64进行了编码

Base64.getEncoder().encodeToString(encryptedData)

而在我进行解密的时候，直接使用了字符串的getByte获取了字节数组，导致得到的字节数组无法被秘钥解密。应该先使用Base64进行解码获取字节数组，

byte[] encryptedData = Base64.getDecoder().decode(encryptedDataString);

完整代码

• 公共参数

   /**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";

    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";

    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;

    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;

• 生成密钥对

/**
     * 

     * 生成密钥对(公钥和私钥)
     * 
     *
     * @return
     * @throws Exception
     */
    public static Map<String, String> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, String> keyMap = new HashMap<String, String>(2);
        keyMap.put(PUBLIC_KEY, Base64.getEncoder().encodeToString(publicKey.getEncoded()));
        keyMap.put(PRIVATE_KEY, Base64.getEncoder().encodeToString(privateKey.getEncoded()));
        return keyMap;
    }

• 公钥加密

 /**
     * 

     * 公钥加密
     * 
     *
     * @param dataBase64String 源数据
     * @param publicKey        公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static String encryptByPublicKey(String dataBase64String, String publicKey) throws Exception {
        byte[] data = dataBase64String.getBytes();
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return Base64.getEncoder().encodeToString(encryptedData);
    }

• 私钥解密

/**
     * 

     * 私钥解密
     * 
     *
     * @param encryptedDataString 已加密数据
     * @param privateKey          私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static String decryptByPrivateKey(String encryptedDataString, String privateKey) throws Exception {
        //byte[] encryptedData = encryptedDataString.getBytes();
        //应该先使用Base64方式进行解码
        byte[] encryptedData = Base64.getDecoder().decode(encryptedDataString);
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return new String(decryptedData);
    }

• 测试代码

public static void main(String[] args) throws Exception {
        Map<String, String> stringObjectMap = genKeyPair();
        String rsaPublicKey = stringObjectMap.get("RSAPublicKey");
        String rsaPrivateKey = stringObjectMap.get("RSAPrivateKey");
        System.out.println("公钥为：" + rsaPublicKey);
        System.out.println("私钥为：" + rsaPrivateKey);
        String text = "!1Qq@2Ww哈哈";

        String publicText = encryptByPublicKey(text, rsaPublicKey);
        System.out.println("公钥加密的信息为：" + publicText);

        String privateText = decryptByPrivateKey(publicText, rsaPrivateKey);
        System.out.println("私钥解密的信息为" + privateText);

    }

总结

其实，加密和解密都是对字节数组进行的操作，只要保证加密后的字节数组和解密前的字节数组一致就可以，以上我犯的错误就是加了一层Base64编码，但是没有使用Base64解码导致的，以后还是得更新细心鸭