RSA加密、解密、签名、验签方法

穆子琪
2023-12-01

1、RSAEncrypt.java:

    public class RSAEncrypt {
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117
    /**
     * RSA最大加密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128
    /**
     * 字节数据转字符串专用集合
     */
    private static final char[] HEX_CHAR = { '0', '1', '2', '3', '4', '5', '6',
            '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

    /**
     * 随机生成密钥对
     */
    public static void genKeyPair(String filePath) {
        // KeyPairGenerator类用于生成公钥和私钥对,基于RSA算法生成对象
        KeyPairGenerator keyPairGen = null;
        try {
            keyPairGen = KeyPairGenerator.getInstance("RSA");
        } catch (NoSuchAlgorithmException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // 初始化密钥对生成器,密钥大小为96-1024位
        keyPairGen.initialize(1024,new SecureRandom());
        // 生成一个密钥对,保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        // 得到私钥
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        // 得到公钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        try {
            // 得到公钥字符串
            String publicKeyString = Base64.encode(publicKey.getEncoded());
            // 得到私钥字符串
            String privateKeyString = Base64.encode(privateKey.getEncoded());
            // 将密钥对写入到文件
            FileWriter pubfw = new FileWriter(filePath + "/publicKey.keystore");
            FileWriter prifw = new FileWriter(filePath + "/privateKey.keystore");
            BufferedWriter pubbw = new BufferedWriter(pubfw);
            BufferedWriter pribw = new BufferedWriter(prifw);
            pubbw.write(publicKeyString);
            pribw.write(privateKeyString);
            pubbw.flush();
            pubbw.close();
            pubfw.close();
            pribw.flush();
            pribw.close();
            prifw.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 从文件中输入流中加载公钥
     *
     * @param in
     *            公钥输入流
     * @throws Exception
     *             加载公钥时产生的异常
     */
    public static String loadPublicKeyByFile(String path) throws Exception {
        //这种方式读取不到打包之后resources目录下文件
        /*        try {
            BufferedReader br = new BufferedReader(new FileReader(path
                    + "/publicKey.keystore"));
            String readLine = null;
            StringBuilder sb = new StringBuilder();
            while ((readLine = br.readLine()) != null) {
                sb.append(readLine);
            }
            br.close();
            return sb.toString();
        } catch (IOException e) {
            throw new Exception("公钥数据流读取错误");
        } catch (NullPointerException e) {
            throw new Exception("公钥输入流为空");
        }*/


        ClassPathResource resource   =    new ClassPathResource("keystore/publicKey.keystore");
        InputStream inputStream  resource.getInputStream();
        //ByteStreams使用com.google.common.io.ByteStreams包
        String key =   new String(ByteStreams.toByteArray(inputStream),"UTF-8");
        if (key !== null && key !=="") {
            return key;
        }else {
            throw new Exception("公钥输入为空")
        }
    }

    /**
     * 从字符串中加载公钥
     *
     * @param publicKeyStr
     *            公钥数据字符串
     * @throws Exception
     *             加载公钥时产生的异常
     */
    public static RSAPublicKey loadPublicKeyByStr(String publicKeyStr)
            throws Exception {
        try {
            byte[] buffer = Base64.decode(publicKeyStr);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
            return (RSAPublicKey) keyFactory.generatePublic(keySpec);
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此算法");
        } catch (InvalidKeySpecException e) {
            throw new Exception("公钥非法");
        } catch (NullPointerException e) {
            throw new Exception("公钥数据为空");
        }
    }

    /**
     * 从文件中加载私钥
     *
     * @param keyFileName
     *            私钥文件名
     * @return 是否成功
     * @throws Exception
     */
    public static String loadPrivateKeyByFile(String path) throws Exception {


    public static RSAPrivateKey loadPrivateKeyByStr(String privateKeyStr)
            throws Exception {
        try {
            byte[] buffer = Base64.decode(privateKeyStr);
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此算法");
        } catch (InvalidKeySpecException e) {
            throw new Exception("私钥非法");
        } catch (NullPointerException e) {
            throw new Exception("私钥数据为空");
        }
    }
    /*        try {
            BufferedReader br = new BufferedReader(new FileReader(path
                    + "/privateKey.keystore"));
            String readLine = null;
            StringBuilder sb = new StringBuilder();
            while ((readLine = br.readLine()) != null) {
                sb.append(readLine);
            }
            br.close();
            return sb.toString();
        } catch (IOException e) {
            throw new Exception("私钥数据读取错误");
        } catch (NullPointerException e) {
            throw new Exception("私钥输入流为空");
        }*/
        ClassPathResource resource   =    new ClassPathResource("keystore/privateKey.keystore");
        InputStream inputStream  resource.getInputStream();
        //ByteStreams使用com.google.common.io.ByteStreams包
        String key =   new String(ByteStreams.toByteArray(inputStream),"UTF-8");
        if (key !== null && key !=="") {
            return key;
        }else {
            throw new Exception("私钥输入为空")
        }
    }

    /**
     * 公钥加密过程
     *
     * @param publicKey
     *            公钥
     * @param plainTextData
     *            明文数据
     * @return
     * @throws Exception
     *             加密过程中的异常信息
     */
    public static byte[] encrypt(RSAPublicKey publicKey, byte[] plainTextData) throws Exception {
        if (publicKey == null) {
            throw new Exception("加密公钥为空, 请设置");
        }
        Cipher cipher = null;
        try {
            // 使用默认RSA
            cipher = Cipher.getInstance("RSA");
            // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            int inputLen = plainTextData.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(plainTextData, offSet, MAX_ENCRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(plainTextData, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_ENCRYPT_BLOCK;
            }
            byte[] output = out.toByteArray();
            out.close();

            return output;
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此加密算法");
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
            return null;
        } catch (InvalidKeyException e) {
            throw new Exception("加密公钥非法,请检查");
        } catch (IllegalBlockSizeException e) {
            throw new Exception("明文长度非法");
        } catch (BadPaddingException e) {
            throw new Exception("明文数据已损坏");
        }
    }
    /**
     * 私钥加密过程
     *
     * @param privateKey
     *            私钥
     * @param plainTextData
     *            明文数据
     * @return
     * @throws Exception
     *             加密过程中的异常信息
     */
    public static byte[] encrypt(RSAPrivateKey privateKey, byte[] plainTextData) throws Exception {
        if (privateKey == null) {
            throw new Exception("加密私钥为空, 请设置");
        }
        Cipher cipher = null;
        try {
            // 使用默认RSA
            cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);
            int inputLen = plainTextData.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(plainTextData, offSet, MAX_ENCRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(plainTextData, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_ENCRYPT_BLOCK;
            }
            byte[] output = out.toByteArray();
            out.close();
            return output;
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此加密算法");
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
            return null;
        } catch (InvalidKeyException e) {
            throw new Exception("加密私钥非法,请检查");
        } catch (IllegalBlockSizeException e) {
            throw new Exception("明文长度非法");
        } catch (BadPaddingException e) {
            throw new Exception("明文数据已损坏");
        }
    }

    /**
     * 私钥解密过程
     *
     * @param privateKey 私钥
     * @param cipherData 密文数据
     * @return 明文
     * @throws Exception 解密过程中的异常信息
     */
    public static byte[] decrypt(RSAPrivateKey privateKey, byte[] cipherData) throws Exception {
        if (privateKey == null) {
            throw new Exception("解密私钥为空, 请设置");
        }
        Cipher cipher = null;
        try {
            // 使用默认RSA
            cipher = Cipher.getInstance("RSA");
            // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            int inputLen = cipherData.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(cipherData, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(cipherData, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            return decryptedData;
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此解密算法");
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
            return null;
        } catch (InvalidKeyException e) {
            throw new Exception("解密私钥非法,请检查");
        } catch (IllegalBlockSizeException e) {
            throw new Exception("密文长度非法");
        } catch (BadPaddingException e) {
            throw new Exception("密文数据已损坏");
        }
    }

    /**
     * 公钥解密过程
     *
     * @param publicKey 公钥
     * @param cipherData 密文数据
     * @return 明文
     * @throws Exception 解密过程中的异常信息
     */
    public static byte[] decrypt(RSAPublicKey publicKey, byte[] cipherData) throws Exception {
        if (publicKey == null) {
            throw new Exception("解密公钥为空, 请设置");
        }
        Cipher cipher = null;
        try {
            // 使用默认RSA
            cipher = Cipher.getInstance("RSA");
            // cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
            cipher.init(Cipher.DECRYPT_MODE, publicKey);
            int inputLen = cipherData.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(cipherData, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(cipherData, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            return decryptedData;
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此解密算法");
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
            return null;
        } catch (InvalidKeyException e) {
            throw new Exception("解密公钥非法,请检查");
        } catch (IllegalBlockSizeException e) {
            throw new Exception("密文长度非法");
        } catch (BadPaddingException e) {
            throw new Exception("密文数据已损坏");
        }
    }
    /**
     * 字节数据转十六进制字符串
     *
     * @param data
     *            输入数据
     * @return 十六进制内容
     */
    public static String byteArrayToString(byte[] data) {
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < data.length; i++) {
            // 取出字节的高四位 作为索引得到相应的十六进制标识符 注意无符号右移
            stringBuilder.append(HEX_CHAR[(data[i] & 0xf0) >>> 4]);
            // 取出字节的低四位 作为索引得到相应的十六进制标识符
            stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);
            if (i < data.length - 1) {
                stringBuilder.append(' ');
            }
        }
        return stringBuilder.toString();
    }
}

2、RSASignature.java:

    public class RSASignature {
    /**
     * 签名算法
     */
    public static final String SIGN_ALGORITHMS = "SHA1WithRSA";

    /**
     * RSA签名
     *
     * @param content
     *            待签名数据
     * @param privateKey
     *            商户私钥
     * @param encode
     *            字符集编码
     * @return 签名值
     */
    public static String sign(String content, String privateKey, String encode) {
        try {
            PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(
                    Base64.decode(privateKey));

            KeyFactory keyf = KeyFactory.getInstance("RSA");
            PrivateKey priKey = keyf.generatePrivate(priPKCS8);

            java.security.Signature signature = java.security.Signature
                    .getInstance(SIGN_ALGORITHMS);

            signature.initSign(priKey);
            signature.update(content.getBytes(encode));

            byte[] signed = signature.sign();

            return Base64.encode(signed);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    public static String sign(String content, String privateKey) {
        try {
            PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(
                    Base64.decode(privateKey));
            KeyFactory keyf = KeyFactory.getInstance("RSA");
            PrivateKey priKey = keyf.generatePrivate(priPKCS8);
            java.security.Signature signature = java.security.Signature
                    .getInstance(SIGN_ALGORITHMS);
            signature.initSign(priKey);
            signature.update(content.getBytes());
            byte[] signed = signature.sign();
            return Base64.encode(signed);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * RSA验签名检查
     *
     * @param content
     *            待签名数据
     * @param sign
     *            签名值
     * @param publicKey
     *            分配给开发商公钥
     * @param encode
     *            字符集编码
     * @return 布尔值
     */
    public static boolean doCheck(String content, String sign,
                                  String publicKey, String encode) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] encodedKey = Base64.decode(publicKey);
            PublicKey pubKey = keyFactory
                    .generatePublic(new X509EncodedKeySpec(encodedKey));

            java.security.Signature signature = java.security.Signature
                    .getInstance(SIGN_ALGORITHMS);

            signature.initVerify(pubKey);
            signature.update(content.getBytes(encode));

            boolean bverify = signature.verify(Base64.decode(sign));
            return bverify;

        } catch (Exception e) {
            e.printStackTrace();
        }

        return false;
    }

    public static boolean doCheck(String content, String sign, String publicKey) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] encodedKey = Base64.decode(publicKey);
            PublicKey pubKey = keyFactory
                    .generatePublic(new X509EncodedKeySpec(encodedKey));

            java.security.Signature signature = java.security.Signature
                    .getInstance(SIGN_ALGORITHMS);

            signature.initVerify(pubKey);
            signature.update(content.getBytes());

            boolean bverify = signature.verify(Base64.decode(sign));
            return bverify;

        } catch (Exception e) {
            e.printStackTrace();
        }

        return false;
    }

    public static void main(String[] args) throws Exception {
        String filepath="F:/tmp/";

        RSAEncrypt.genKeyPair(filepath);


        System.out.println("--------------公钥加密私钥解密过程-------------------");
        String plainText="ihep_公钥加密私钥解密    原文 为改变";
        //公钥加密过程
        byte[] cipherData=RSAEncrypt.encrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)),plainText.getBytes());
        String cipher=Base64.encode(cipherData);
        //私钥解密过程
        byte[] res=RSAEncrypt.decrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)), Base64.decode(cipher));
        String restr=new String(res);
        System.out.println("原文:"+plainText);
        System.out.println("加密:"+cipher);
        System.out.println("解密:"+restr);
        System.out.println();

        System.out.println("--------------私钥加密公钥解密过程-------------------");
        plainText="ihep_私钥加密公钥解密 为改变";
        //私钥加密过程
        cipherData=RSAEncrypt.encrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)),plainText.getBytes());
        cipher=Base64.encode(cipherData);
        //公钥解密过程
        res=RSAEncrypt.decrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)), Base64.decode(cipher));
        restr=new String(res);
        System.out.println("原文:"+plainText);
        System.out.println("加密:"+cipher);
        System.out.println("解密:"+restr);
        System.out.println();

        System.out.println("---------------私钥签名过程------------------");
        String content="ihep_这是用于签名的原始数据";
        String signstr=RSASignature.sign(content,RSAEncrypt.loadPrivateKeyByFile(filepath));
        System.out.println("签名原串:"+content);
        System.out.println("签名串:"+signstr);
        System.out.println();

        System.out.println("---------------公钥校验签名------------------");
        System.out.println("签名原串:"+content);
        System.out.println("签名串:"+signstr);

        System.out.println("验签结果:"+RSASignature.doCheck(content, signstr, RSAEncrypt.loadPublicKeyByFile(filepath)));
        System.out.println();

    }

3、Base64.java:

    public class Base64 {
    static private final int     BASELENGTH           = 128;
    static private final int     LOOKUPLENGTH         = 64;
    static private final int     TWENTYFOURBITGROUP   = 24;
    static private final int     EIGHTBIT             = 8;
    static private final int     SIXTEENBIT           = 16;
    static private final int     FOURBYTE             = 4;
    static private final int     SIGN                 = -128;
    static private final char    PAD                  = '=';
    static private final boolean fDebug               = false;
    static final private byte[]  base64Alphabet       = new byte[BASELENGTH];
    static final private char[]  lookUpBase64Alphabet = new char[LOOKUPLENGTH];
    static {
        for (int i = 0; i < BASELENGTH; ++i) {
            base64Alphabet[i] = -1;
        }
        for (int i = 'Z'; i >= 'A'; i--) {
            base64Alphabet[i] = (byte) (i - 'A');
        }
        for (int i = 'z'; i >= 'a'; i--) {
            base64Alphabet[i] = (byte) (i - 'a' + 26);
        }

        for (int i = '9'; i >= '0'; i--) {
            base64Alphabet[i] = (byte) (i - '0' + 52);
        }

        base64Alphabet['+'] = 62;
        base64Alphabet['/'] = 63;

        for (int i = 0; i <= 25; i++) {
            lookUpBase64Alphabet[i] = (char) ('A' + i);
        }

        for (int i = 26, j = 0; i <= 51; i++, j++) {
            lookUpBase64Alphabet[i] = (char) ('a' + j);
        }

        for (int i = 52, j = 0; i <= 61; i++, j++) {
            lookUpBase64Alphabet[i] = (char) ('0' + j);
        }
        lookUpBase64Alphabet[62] = (char) '+';
        lookUpBase64Alphabet[63] = (char) '/';

    }

    private static boolean isWhiteSpace(char octect) {
        return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
    }

    private static boolean isPad(char octect) {
        return (octect == PAD);
    }

    private static boolean isData(char octect) {
        return (octect < BASELENGTH && base64Alphabet[octect] != -1);
    }

    /**
     * Encodes hex octects into Base64
     *
     * @param binaryData Array containing binaryData
     * @return Encoded Base64 array
     */
    public static String encode(byte[] binaryData) {

        if (binaryData == null) {
            return null;
        }

        int lengthDataBits = binaryData.length * EIGHTBIT;
        if (lengthDataBits == 0) {
            return "";
        }

        int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
        int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
        int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
        char encodedData[] = null;

        encodedData = new char[numberQuartet * 4];

        byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;

        int encodedIndex = 0;
        int dataIndex = 0;
        if (fDebug) {
            System.out.println("number of triplets = " + numberTriplets);
        }

        for (int i = 0; i < numberTriplets; i++) {
            b1 = binaryData[dataIndex++];
            b2 = binaryData[dataIndex++];
            b3 = binaryData[dataIndex++];

            if (fDebug) {
                System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
            }

            l = (byte) (b2 & 0x0f);
            k = (byte) (b1 & 0x03);

            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
            byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);

            if (fDebug) {
                System.out.println("val2 = " + val2);
                System.out.println("k4   = " + (k << 4));
                System.out.println("vak  = " + (val2 | (k << 4)));
            }

            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
        }

        // form integral number of 6-bit groups
        if (fewerThan24bits == EIGHTBIT) {
            b1 = binaryData[dataIndex];
            k = (byte) (b1 & 0x03);
            if (fDebug) {
                System.out.println("b1=" + b1);
                System.out.println("b1<<2 = " + (b1 >> 2));
            }
            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
            encodedData[encodedIndex++] = PAD;
            encodedData[encodedIndex++] = PAD;
        } else if (fewerThan24bits == SIXTEENBIT) {
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            l = (byte) (b2 & 0x0f);
            k = (byte) (b1 & 0x03);

            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);

            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
            encodedData[encodedIndex++] = PAD;
        }

        return new String(encodedData);
    }

    /**
     * Decodes Base64 data into octects
     *
     * @param encoded string containing Base64 data
     * @return Array containind decoded data.
     */
    public static byte[] decode(String encoded) {

        if (encoded == null) {
            return null;
        }

        char[] base64Data = encoded.toCharArray();
        // remove white spaces
        int len = removeWhiteSpace(base64Data);

        if (len % FOURBYTE != 0) {
            return null;//should be divisible by four
        }

        int numberQuadruple = (len / FOURBYTE);

        if (numberQuadruple == 0) {
            return new byte[0];
        }

        byte decodedData[] = null;
        byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
        char d1 = 0, d2 = 0, d3 = 0, d4 = 0;

        int i = 0;
        int encodedIndex = 0;
        int dataIndex = 0;
        decodedData = new byte[(numberQuadruple) * 3];

        for (; i < numberQuadruple - 1; i++) {

            if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
                    || !isData((d3 = base64Data[dataIndex++]))
                    || !isData((d4 = base64Data[dataIndex++]))) {
                return null;
            }//if found "no data" just return null

            b1 = base64Alphabet[d1];
            b2 = base64Alphabet[d2];
            b3 = base64Alphabet[d3];
            b4 = base64Alphabet[d4];

            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
        }

        if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
            return null;//if found "no data" just return null
        }

        b1 = base64Alphabet[d1];
        b2 = base64Alphabet[d2];

        d3 = base64Data[dataIndex++];
        d4 = base64Data[dataIndex++];
        if (!isData((d3)) || !isData((d4))) {//Check if they are PAD characters
            if (isPad(d3) && isPad(d4)) {
                if ((b2 & 0xf) != 0)//last 4 bits should be zero
                {
                    return null;
                }
                byte[] tmp = new byte[i * 3 + 1];
                System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                return tmp;
            } else if (!isPad(d3) && isPad(d4)) {
                b3 = base64Alphabet[d3];
                if ((b3 & 0x3) != 0)//last 2 bits should be zero
                {
                    return null;
                }
                byte[] tmp = new byte[i * 3 + 2];
                System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                return tmp;
            } else {
                return null;
            }
        } else { //No PAD e.g 3cQl
            b3 = base64Alphabet[d3];
            b4 = base64Alphabet[d4];
            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);

        }

        return decodedData;
    }

    /**
     * remove WhiteSpace from MIME containing encoded Base64 data.
     *
     * @param data  the byte array of base64 data (with WS)
     * @return      the new length
     */
    private static int removeWhiteSpace(char[] data) {
        if (data == null) {
            return 0;
        }

        // count characters that's not whitespace
        int newSize = 0;
        int len = data.length;
        for (int i = 0; i < len; i++) {
            if (!isWhiteSpace(data[i])) {
                data[newSize++] = data[i];
            }
        }
        return newSize;
    }


4、test:


        //原数据进行签名
        //log.info("原数据:" + signature);
        String signature = "12345dfadffzdfca";//签名数据
        String sign = null;
        try {
        sign = RSASignature.sign(signature, RSAEncrypt.loadPrivateKeyByFile());
        } catch (Exception e) {
        e.printStackTrace();
        }
        log.info("原数据签名:" + sign);
        settleDocumentNoInputDto.setSIGNATURE(sign);
        //对input进行加密
        byte[] cipherData = new byte[0];
        try {
        cipherData =
        RSAEncrypt.encrypt(
        RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile()), s.getBytes());
        } catch (Exception e) {
        e.printStackTrace();
        }
        String cipher = Base64.encode(cipherData);
        log.info("input加密之后数据:" + cipher);
        settleDocumentNoInputDto.setINPUT(cipher);

        String settlement =
        OkhttpUtil.okHttpPostJsonReturn(
        url, JsonConverUtils.beanToJsonByJackson(Dto, ""));

        Output settlementList =
        JsonConverUtils.jsonToBeanByJackson(settlement, Output.class, "");

        if (ObjectUtils.isEmpty(settlementList) || StringUtils.isBlank(settlementList.getOUTPUT())) {
        log.error("调用接口成功,解析返回数据为空!");
        return;
        }
        byte[] res = new byte[0];
        try {
        res =
        RSAEncrypt.decrypt(
        RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile()),
        Base64.decode(settlementList.getOUTPUT()));
        } catch (Exception e) {
        e.printStackTrace();
        }
        String s1 = new String(res);
        //log.info("私钥解密output后数据为" + s1);
        if (null == res) {
        log.info("OUTPUT 解密后为空");
        return;
        }

        if (StringUtils.isBlank(s1)) {
        return;
        }
    /* boolean b = false;
    try {
      b = RSASignature.doCheck(signature, sign, RSAEncrypt.loadPublicKeyByFile());
    } catch (Exception e) {
      e.printStackTrace();
    }
    if (!b) {
      log.error("验签失败");
      return;
    }*/
        // log.info("验签成功");
        JsonNode jsonNode = JsonConverUtils.string2Jsonnode(s1);
        String list = jsonNode.toString();
        Dto =
        JsonConverUtils.jsonToBeanByJackson(list, Dto.class, "");
        
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