Java实现RSA签名以及验签代码示例

项目介绍

最近需要实现对接口的签名和加密，特此整理一下，方便以后查看。
使用的是RSA非对称加密，签名方法用的是RSA自带的。
签名原理，私钥签名，公钥验签
需要三个工具类：BASE64.java      RSAEncrypt.java      RSASignature.java
流程图如下(无证书情况)   如果第三方不想让接口提供方知道他们的私钥，可以让第三方自己生成公私钥，把公钥公开出来   验签得双方验证才行，就是说双方都得有自己的公私钥，传输过程带上自己的公钥去验证，但是这有个问题，这个公私钥的合法性，如果是用证书可以用证书链的验证解决

***

签名生成通用规则

---

签名原文组装说明：
无论是请求还是响应，签名原文组装规则如下：
1)除sign字段外，所有参数按照字段名的ASCII字码从小到大排序。排序完成之后，再把所有键值对以“&”字符连接起来(如key1=value1&key2=value2)。
2)如果参数值是一个子JSONObject，则先将子JSON按照字段名的ASCII字码从小到大排序，把子JSON中的所有键值对以“&”字符连接起来，以此作为该参数的值，再进行拼接。
3)如果参数值是一个JSON数组，需要把JSON数组里面的内容转换成字符串，然后按照字段名的ASCII字码从小到大排序，把子JSON中的所有键值对以“&”字符连接起来，以此作为该参数的值，再进行拼接。
4)所有参数是指实际出现的所有非空参数，即使是没有事先描述的非空字段，也需要参与签名组串。
5)签名原始串中，各字段和字段值都采用原始值，不进行URLEncoder。
6)参数名区分大小写。

签名(sign)生成通用步骤：

对上述拼接好的data_to_sign使用商户的私钥进行RSA签名
示例如下：
假设传递的json串如下：
{"area":"郑州",
"email":"[e-mail]",
"frimname":"张三",
"idNumber":"320206198611222555",
"name":"赵六",
"phone":"17839949863"}
1、拼接的待签原文(data_to_sign)：
email=[e-mail]&frimname=张三&idNumber=320206198611222555&name=赵六&phone=17839949869
2、使用线下拿到的私钥进行签名,sign=sign(data_to_sign,私钥));
3、执行成功后，会得到一个sign，是由接口返回的签名，再用data_to_sign和
服务商的公钥验证签名，保证数据没被篡改。

BASE64

import org.apache.tomcat.util.codec.binary.Base64;
import sun.misc.BASE64Encoder;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;

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) '/';

    }




    /**
     * 将本地图片进行Base64位编码
     *
     * @param imgUrl 图片的url路径，如D:\\photo\\1.png
     *
     * @return
     */
    public static String encodeImgageToBase64(File imageFile) {
        // 将图片文件转化为字节数组字符串，并对其进行Base64编码处理
        // 其进行Base64编码处理
        byte[] data = null;
        // 读取图片字节数组
        try {
            InputStream in = new FileInputStream(imageFile);
            data = new byte[in.available()];
            in.read(data);
            in.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 对字节数组Base64编码
        BASE64Encoder encoder = new BASE64Encoder();
        // 返回Base64编码过的字节数组字符串
        return encoder.encode(data);

    }


    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;
    }


    /**
     *
     * 功能描述：Base64加密（将byte[]转换成字符串）  方法。
     * <P/>
     * 创建时间：2017-02-14
     * <P/>
     * 创建人： 董耀明
     *
     * @param data byte[]类型 要加密的数据
     *
     * @return String类型 加密后结果
     *
     */
    public static String encryptBASE64(byte[] data)
    {
        return Base64.encodeBase64String(data);
        //return (new BASE64Encoder()).encodeBuffer(data);
    }


    /**
     *
     * 功能描述：Base64加密（将byte[]转换成字符串）  方法。
     * <P/>
     * 创建时间：2017-02-14
     * <P/>
     * 创建人： 董耀明
     *
     * @param data String类型 要加密的数据
     *
     * @return String类型 加密后结果
     *
     */
    public static String encryptBASE64(String data)
    {
        try {
            //return (new BASE64Encoder()).encodeBuffer(data.getBytes("UTF-8"));
            return Base64.encodeBase64String(data.getBytes("UTF-8"));
        } catch (Exception e) {
            return null;
        }
    }

    /**
     *
     * 功能描述：Base64加密（将byte[]转换成字符串）  方法。
     * <P/>
     * 创建时间：2017-02-14
     * <P/>
     * 创建人： 董耀明
     *
     * @param data String类型 要加密的数据
     *
     * @param encode String类型 编码类型
     *
     * @return String类型 加密后结果
     *
     */
    public static String encryptBASE64(String data,String encode)
    {

        try
        {
            if (encode == null || "".equals(encode))
            {

                return Base64.encodeBase64String(data.getBytes());

            } else
            {
                return Base64.encodeBase64String(data.getBytes(encode));
            }

        } catch (UnsupportedEncodingException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
    }

}

RSAEncrypt

因为业务需求，我把自己用的公私钥分别命名为  publicKey.keystore  和  privateKey.keystore 保存在了FTP服务器里，
读取也是从FTP服务器读。(接口提供方只需要生成一次公私钥，把公钥给第三方，用于加密)

/**
 *  @author: zph
 *  @Date: 2020/7/10 15:28
 *  @Description: RSA加密解密工具类
 */
public class RSAEncrypt {
    /**
     * 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' };


    // FTP服务器hostname
    public static String HOST = "";

    // FTP服务器端口
    public static Integer PORT = ;

    // FTP登录账号
    public static String USERNAME = "";

    // FTP登录密码
    public static String PASSWORD = "";

    // FTP上传路径
    public static String  INVOICE_BASE_PATH = "";
    /**
     * 随机生成密钥对
     */
    public static void genKeyPair() {
        // 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());
            System.err.println(publicKeyString);
            System.err.println(privateKeyString);
            // 将公密钥对写入到文件
            /*InputStream is = null;
            InputStream is1 = null;
            is = new ByteArrayInputStream(publicKeyString.getBytes());
            is1 = new ByteArrayInputStream(privateKeyString.getBytes());
            FTPClient ftpClient = new FTPClient();
            ftpClient.connect(HOST);
            ftpClient.login(USERNAME,PASSWORD);
            ftpClient.changeWorkingDirectory(INVOICE_BASE_PATH);
            ftpClient.setFileType(FTPClient.LOCAL_FILE_TYPE);
            ftpClient.storeFile(new String("publicKey.keystore".getBytes(),"iso-8859-1"),is);
            ftpClient.storeFile(new String("privateKey.keystore".getBytes(),"iso-8859-1"),is1);
            is.close();
            is1.close();*/
            //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
     *
     * @throws Exception
     *             加载公钥时产生的异常
     */
    public static String loadPublicKeyByFile() throws Exception {
        try {
            FTPClient ftpClient = new FTPClient();
            ftpClient.connect(HOST);
            ftpClient.login(USERNAME,PASSWORD);
            ftpClient.changeWorkingDirectory(INVOICE_BASE_PATH);
            InputStream is = ftpClient.retrieveFileStream("publicKey.keystore");
            BufferedReader br = new BufferedReader(new InputStreamReader(is,"UTF-8"));
            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");
        }
    }

    /**
     * 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
     *
     * @return 是否成功
     * @throws Exception
     */
    public static String loadPrivateKeyByFile() throws Exception {
        try {
            FTPClient ftpClient = new FTPClient();
            ftpClient.connect(HOST);
            ftpClient.login(USERNAME,PASSWORD);
            ftpClient.changeWorkingDirectory(INVOICE_BASE_PATH);
            InputStream is = ftpClient.retrieveFileStream("privateKey.keystore");
            BufferedReader br = new BufferedReader(new InputStreamReader(is,"UTF-8"));
            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");
        }
    }

    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");
        }
    }

    /**
     * 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);
            byte[] output = cipher.doFinal(plainTextData);
            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);
            byte[] output = cipher.doFinal(plainTextData);
            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);
            byte[] output = cipher.doFinal(cipherData);
            return output;
        } 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);
            byte[] output = cipher.doFinal(cipherData);
            return output;
        } 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();
    }
}

RSASignature

import java.lang.reflect.Field;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

/**
 *  @author: zph
 *  @Date: 2020/7/10 15:29
 *  @Description: RSA签名验签类
 */
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;
    }

    /**
     * 根据 content 和 私钥  生成签名
     * @param content  按字典顺序排序的内容
     * @param privateKey  ftp上保存的私钥
     * @return
     */
    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;
    }

    /**
     * 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
     * @return 布尔值
     */
    public static boolean doCheck(String content, String sign, String publicKey)
    {
        try
        {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] encodedKey = BASE64.decode(publicKey);
            if (encodedKey==null){
                return false;
            }
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));

            // 用私钥对信息生成数字签名
            java.security.Signature signature = java.security.Signature
                    .getInstance(SIGN_ALGORITHMS);

            signature.initVerify(pubKey);
            signature.update( content.getBytes() );
            // 验证方法  返回true则为比对成功
            boolean bverify = signature.verify( BASE64.decode(sign) );
            return bverify;

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

        return false;
    }


    /**
     * 对象转HashMap
     * @param obj
     * @return
     */
    public static Map<String, Object> objectToMap(Object obj) {
        if (obj == null) {
            return null;
        }

        Map<String, Object> map = new HashMap<String, Object>();
        try {
            Field[] declaredFields = obj.getClass().getDeclaredFields();
            for (Field field : declaredFields) {
                field.setAccessible(true);
                map.put(field.getName(), field.get(obj));
            }
        } catch (Exception e) {

        }

        return map;
    }

    /**
     *  @author: zph
     *  @Date: 2020/7/14 17:45
     *  @Description: 将签名的参数内容按参数名的字典顺序进行排序，并拼接为字符串
     */
    public static String getContent(Map<String,Object> map){
        //得到第三方签名 第三方会把sign也放在json里，故转map的时候需要把sign删除
        map.remove("sign");
        map.entrySet().removeIf(entry -> entry.getValue() == null);
        // 将签名的参数内容按参数名的字典顺序进行排序，并拼接为字符串
        StringBuilder sb = new StringBuilder();
        map.entrySet().stream().sorted(Comparator.comparing(Map.Entry::getKey)).forEach(entry ->
                sb.append(entry.getKey()).append("=").append(entry.getValue()).append("&")
        );
        return sb.toString().substring(0, sb.length() - 1);
    }

    /**
     * 签名方法
     * 因为很多处都需要用，特地封装一下，方便调用
     * @param paramStr   按字典顺序拼接过的字符串
     * @param publicKey  从数据库查询出来的第三方公钥
     * @param sign  第三方签名
     * @return
     */
    public static boolean signVerify(String paramStr,String publicKey,String sign){
        System.err.println(paramStr);
        try {
            //String privateSign = RSASignature.sign(paramStr, RSAEncrypt.loadPrivateKeyByFile());
            // 使用公钥进行验签
            boolean result = RSASignature.doCheck(paramStr, sign, publicKey);
            if (result){
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }


}

Main方法

public static void main(String[] args) {
         try {
             // 生成密钥对
             KeyPair keyPair = getKeyPair();
             String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
             String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
            System.out.println("私钥:" + privateKey);
             System.out.println("公钥:" + publicKey);
             // RSA加密
             String data = "待加密的文字内容";
             String encryptData = encrypt(data, getPublicKey(publicKey));
             System.out.println("加密后内容:" + encryptData);
             // RSA解密
             String decryptData = decrypt(encryptData, getPrivateKey(privateKey));
             System.out.println("解密后内容:" + decryptData);
             
             // RSA签名
             String sign = sign(data, getPrivateKey(privateKey));
             // RSA验签
             boolean result = verify(data, getPublicKey(publicKey), sign);
             System.out.print("验签结果:" + result);
         } catch (Exception e) {
             e.printStackTrace();
             System.out.print("加解密异常");
         }
     }

本文地址：https://blog.csdn.net/qq_38799009/article/details/107359515