Java实现RSA密钥对并在加解密、加签验签中应用的实例

2023-01-01 07:38:28

一.项目结构

二.代码具体实现

1.密钥对生成的两种方式：一种生成公钥私文件，一种生成公钥私串

KeyPairGenUtil.java

package com.wangjinxiang.genkey.util;

import java.io.FileOutputStream;

import java.io.ObjectOutputStream;

import java.security.Key;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.NoSuchAlgorithmException;

import java.security.SecureRandom;

import sun.misc.BASE64Encoder;

public class KeyPairGenUtil {

    /** 指定加密算法为RSA */

    private static final String ALGORITHM = "RSA";

    /** 密钥长度，用来初始化 */

    private static final int KEYSIZE = 1024;

    /** 指定公钥存放文件 */

    private static String PUBLIC_KEY_FILE = "PublicKey";

    /** 指定私钥存放文件 */

    private static String PRIVATE_KEY_FILE = "PrivateKey";

    public static void main(String[] args) throws Exception {

        //generateKeyPair();

        genKeyPair();

    }

    /**

    * 生成密钥对文件

    * @throws Exception

    */

    private static void generateKeyPair() throws Exception {

        //     /** RSA算法要求有一个可信任的随机数源 */

        //     SecureRandom secureRandom = new SecureRandom();

        /** 为RSA算法创建一个KeyPairGenerator对象 */

        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);

        /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */

        //     keyPairGenerator.initialize(KEYSIZE, secureRandom);

        keyPairGenerator.initialize(KEYSIZE);

        /** 生成密匙对 */

        KeyPair keyPair = keyPairGenerator.generateKeyPair();

        /** 得到公钥 */

        Key publicKey = keyPair.getPublic();

        /** 得到私钥 */

        Key privateKey = keyPair.getPrivate();

        ObjectOutputStream oos1 = null;

        ObjectOutputStream oos2 = null;

        try {

            /** 用对象流将生成的密钥写入文件 */

            oos1 = new ObjectOutputStream(new FileOutputStream(PUBLIC_KEY_FILE));

            oos2 = new ObjectOutputStream(new FileOutputStream(PRIVATE_KEY_FILE));

            oos1.writeObject(publicKey);

            oos2.writeObject(privateKey);

        } catch (Exception e) {

            throw e;

        } finally {

            /** 清空缓存，关闭文件输出流 */

            oos1.close();

            oos2.close();

        }

    }

    /**

     * 生成密钥对

     * @throws NoSuchAlgorithmException

     */

    private static void genKeyPair() throws NoSuchAlgorithmException {

        /** RSA算法要求有一个可信任的随机数源 */

        SecureRandom secureRandom = new SecureRandom();

        /** 为RSA算法创建一个KeyPairGenerator对象 */

        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);

        /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */

        keyPairGenerator.initialize(KEYSIZE, secureRandom);

        //keyPairGenerator.initialize(KEYSIZE);

        /** 生成密匙对 */

        KeyPair keyPair = keyPairGenerator.generateKeyPair();

        /** 得到公钥 */

        Key publicKey = keyPair.getPublic();

        /** 得到私钥 */

        Key privateKey = keyPair.getPrivate();

        byte[] publicKeyBytes = publicKey.getEncoded();

        byte[] privateKeyBytes = privateKey.getEncoded();

        String publicKeyBase64 = new BASE64Encoder().encode(publicKeyBytes);

        String privateKeyBase64 = new BASE64Encoder().encode(privateKeyBytes);

        System.out.println("publicKeyBase64.length():" + publicKeyBase64.length());

        System.out.println("publicKeyBase64:" + publicKeyBase64);

        System.out.println("privateKeyBase64.length():" + privateKeyBase64.length());

        System.out.println("privateKeyBase64:" + privateKeyBase64);

    }

}

2.将密钥串生成方式的密钥对在常量类里定义，以便后面的应用使用

Constants.java

package com.wangjinxiang.constant;

public class Constants {

  //#priKeyText

  public final static String priKeyText = "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";

  //#pubKeyText

  public final static String pubKeyText = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCYO23qMcvv0gpGs97rfmxITjjz5m/sjZ4JgYvPBs+JHwD/SCv7TJCEKVm4aXTEPTXRkN7LgUjQTnEGGS1JBY4zyqpnmJcfpNxWpdgAyE/4poMJ8rcZvqm14DOjNH+69mwpIdJkySHuzUCzQtMJ8GG2owNc9frTOpZozlcUWbGWfQIDAQAB";

}

DigestUtil.java

package com.wangjinxiang.util;

public class DigestUtil {

    /**

     * 字节转为十六进制字符串

     * @param字节

     * @return 十六进制字符串

     */

    public static String byte2hex(byte[] b) {

        String hs = "";

        String stmp = "";

        for (int n = 0; b != null && n < b.length; n++) {

            stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));

            if (stmp.length() == 1)

                hs = hs + "0" + stmp;

            else

                hs = hs + stmp;

        }

        return hs;

    }

    /**

     * 十六进制字符转为字节

     * @param 十六进制字符

     * @return  字节

     */

    public static byte[] hex2byte(byte[] b) {

        if ((b.length % 2) != 0)

            throw new IllegalArgumentException("byte length is not correct");

        byte[] b2 = new byte[b.length / 2];

        for (int n = 0; n < b.length; n += 2) {

            String item = new String(b, n, 2);

            b2[n / 2] = (byte) Integer.parseInt(item, 16);

        }

        return b2;

    }

    /**

     * 字符串转换成十六进制值

     * @param bin String 我们看到的要转换成十六进制的字符串

     * @return

    */

    public static String bin2hex(String bin) {

        char[] digital = "0123456789ABCDEF".toCharArray();

        StringBuffer sb = new StringBuffer("");

        byte[] bs = bin.getBytes();

        int bit;

        for (int i = 0; i < bs.length; i++) {

            bit = (bs[i] & 0x0f0) >> 4;

            sb.append(digital[bit]);

            bit = bs[i] & 0x0f;

            sb.append(digital[bit]);

        }

        return sb.toString();

    }

}

3.加解密应用实例RSAUtil.java

说明：加解密是用公钥加密，用私钥解密

package com.wangjinxiang.util;

import java.security.KeyFactory;

import java.security.PrivateKey;

import java.security.spec.PKCS8EncodedKeySpec;

import javax.crypto.Cipher;

import org.apache.commons.codec.binary.Base64;

import com.wangjinxiang.constant.Constants;

import sun.misc.BASE64Decoder;

import sun.misc.BASE64Encoder;

public class RSAUtil {

    /** 指定加密算法为RSA */

    private static final String ALGORITHM = "RSA";

    public static void main(String[] args) throws Exception {

        String source = "深圳,您好!";// 要加密的字符串

        System.out.println("准备用公钥加密的字符串为：" + source);

        String cryptograph = encrypt(source);// 生成的密文

        System.out.print("用公钥加密后的结果为:" + cryptograph);

        System.out.println();

        String target = decrypt(cryptograph);// 解密密文

        System.out.println("用私钥解密后的字符串为：" + target);

        System.out.println();

    }

    /**

     * 加密方法

     * @param source 源数据

     * @return

     * @throws Exception

     */

    public static String encrypt(String source) throws Exception {

        java.security.spec.X509EncodedKeySpec x509KeySpec = new java.security.spec.X509EncodedKeySpec(Base64.decodeBase64(Constants.pubKeyText));

        // RSA算法

        java.security.KeyFactory keyFactory = java.security.KeyFactory.getInstance("RSA");

        // 取公钥匙对象

        java.security.PublicKey publicKey = keyFactory.generatePublic(x509KeySpec);

        // 得到Cipher对象来实现对源数据的RSA加密

        Cipher cipher = Cipher.getInstance(ALGORITHM);

        cipher.init(Cipher.ENCRYPT_MODE, publicKey);

        byte[] b = source.getBytes();

        /** 执行加密操作 */

        byte[] b1 = cipher.doFinal(b);

        BASE64Encoder encoder = new BASE64Encoder();

        return encoder.encode(b1);

    }

    /**

     * 解密算法

     * @param cryptograph    密文

     * @return

     * @throws Exception

     */

    public static String decrypt(String cryptograph) throws Exception {

        PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64.decodeBase64(Constants.priKeyText));

        KeyFactory keyf = KeyFactory.getInstance("RSA");

        PrivateKey privateKey = keyf.generatePrivate(priPKCS8);

        /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */

        Cipher cipher = Cipher.getInstance(ALGORITHM);

        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        BASE64Decoder decoder = new BASE64Decoder();

        byte[] b1 = decoder.decodeBuffer(cryptograph);

        /** 执行解密操作 */

        byte[] b = cipher.doFinal(b1);

        return new String(b);

    }

}

运行结果：

准备用公钥加密的字符串为：深圳,您好!

用公钥加密后的结果为:Q5bZjBlIIPII04NOCIwYDPYBGNSC5Hv7XKc8TlkCRbZyAK4M4nm9uYcEded0Nbj7HeLXNZY8XrQD

l2+FsYjfL0DlioCoJQm7bnwlVwYmdNMXOB3bfepywpeFRDSNswJxueLqVtmIKcbuCuXBvdIqrfDq

PVbCVfI59/GhqAcqM6U=

用私钥解密后的字符串为：深圳,您好!

4.加签验签实例SignUtil.java

说明：加签是用私钥，验签是用公钥

package com.wangjinxiang.util;

import java.security.KeyFactory;

import java.security.PrivateKey;

import java.security.spec.PKCS8EncodedKeySpec;

import org.apache.commons.codec.binary.Base64;

import com.wangjinxiang.constant.Constants;

public class SignUtil {

    private final static String CHARACTER_ENCODING_UTF_8 = "UTF-8";

    public static void main(String[] args) {

        String signString = "深圳,您好!";

        try {

            // 加签

            String localSignature = SignUtil.sign(Constants.priKeyText.getBytes(CHARACTER_ENCODING_UTF_8), signString);

            System.out.println(localSignature);

            //验签

            boolean verifyResult = SignUtil.verify(Constants.pubKeyText.getBytes(CHARACTER_ENCODING_UTF_8), signString, localSignature);

            System.out.println("verifyResult:" + verifyResult);

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    /**

     * RSA私钥加签

     * @param priKeyText经过base64处理后的私钥

     * @param plainText明文内容

     * @return 十六进制的签名字符串

     * @throws Exception

     */

    public static String sign(byte[] priKeyText, String plainText) throws Exception {

        try {

            PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64.decodeBase64(priKeyText));

            KeyFactory keyf = KeyFactory.getInstance("RSA");

            PrivateKey prikey = keyf.generatePrivate(priPKCS8);

            // 用私钥对信息生成数字签名

            java.security.Signature signet = java.security.Signature.getInstance("SHA256withRSA");

            signet.initSign(prikey);

            signet.update(plainText.getBytes("UTF-8"));

            return DigestUtil.byte2hex(signet.sign());

        } catch (Exception e) {

            throw e;

        }

    }

    /**

     * 公钥验签

     * @param pubKeyText经过base64处理后的公钥

     * @param plainText明文内容

     * @param signText十六进制的签名字符串

     * @return 验签结果 true验证一致 false验证不一致

     */

    public static boolean verify(byte[] pubKeyText, String plainText, String signText) {

        try {

            // 解密由base64编码的公钥,并构造X509EncodedKeySpec对象

            java.security.spec.X509EncodedKeySpec bobPubKeySpec = new java.security.spec.X509EncodedKeySpec(

                    Base64.decodeBase64(pubKeyText));

            // RSA算法

            java.security.KeyFactory keyFactory = java.security.KeyFactory.getInstance("RSA");

            // 取公钥匙对象

            java.security.PublicKey pubKey = keyFactory.generatePublic(bobPubKeySpec);

            // 十六进制数字签名转为字节

            byte[] signed = DigestUtil.hex2byte(signText.getBytes("UTF-8"));

            java.security.Signature signatureChecker = java.security.Signature.getInstance("SHA256withRSA");

            signatureChecker.initVerify(pubKey);

            signatureChecker.update(plainText.getBytes("UTF-8"));

            // 验证签名是否正常

            return signatureChecker.verify(signed);

        } catch (Throwable e) {

            return false;

        }

    }

}

运行结果：

7ef0cd04a3dc41ae1396a90a3d8a8b799c68c65202361823dd3a71a05fc2bf57c09ebe2074ba49008cf58288297267d770137ee267c6c296a784c7d50c607c73e1d78799c7de5dadf183f011d604df7270ce5616e465ddc93a95df9095249702fc265e97ed7ab2adf4535d13237040653d7f000a3080a0c4f11f84bbe48849e7

verifyResult:true

5.从生成的密钥对文件中读取公私钥加解密实例RSAUtil02.java

package com.wangjinxiang.util2;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.security.Key;

import javax.crypto.Cipher;

import sun.misc.BASE64Decoder;

import sun.misc.BASE64Encoder;

public class RSAUtil02 {

    /** 指定加密算法为RSA */

    private static final String ALGORITHM = "RSA";

    /** 指定公钥存放文件 */

    private static String PUBLIC_KEY_FILE = "PublicKey";

    /** 指定私钥存放文件 */

    private static String PRIVATE_KEY_FILE = "PrivateKey";

    public static void main(String[] args) throws Exception {

        String source = "深圳,您好!";// 要加密的字符串

        System.out.println("准备用公钥加密的字符串为：" + source);

        String cryptograph = encrypt(source);// 生成的密文

        System.out.print("用公钥加密后的结果为:" + cryptograph);

        System.out.println();

        String target = decrypt(cryptograph);// 解密密文

        System.out.println("用私钥解密后的字符串为：" + target);

        System.out.println();

    }

    /**

     * 加密方法

     * @param source 源数据

     * @return

     * @throws Exception

     */

    public static String encrypt(String source) throws Exception {

        Key publicKey = getKey(PUBLIC_KEY_FILE);

        /** 得到Cipher对象来实现对源数据的RSA加密 */

        Cipher cipher = Cipher.getInstance(ALGORITHM);

        cipher.init(Cipher.ENCRYPT_MODE, publicKey);

        byte[] b = source.getBytes();

        /** 执行加密操作 */

        byte[] b1 = cipher.doFinal(b);

        BASE64Encoder encoder = new BASE64Encoder();

        return encoder.encode(b1);

    }

    /**

     * 解密算法

     * @param cryptograph    密文

     * @return

     * @throws Exception

     */

    public static String decrypt(String cryptograph) throws Exception {

        Key privateKey = getKey(PRIVATE_KEY_FILE);

        /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */

        Cipher cipher = Cipher.getInstance(ALGORITHM);

        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        BASE64Decoder decoder = new BASE64Decoder();

        byte[] b1 = decoder.decodeBuffer(cryptograph);

        /** 执行解密操作 */

        byte[] b = cipher.doFinal(b1);

        return new String(b);

    }

    private static Key getKey(String fileName) throws Exception, IOException {

        Key key;

        ObjectInputStream ois = null;

        try {

            /** 将文件中的私钥对象读出 */

            ois = new ObjectInputStream(new FileInputStream(fileName));

            key = (Key) ois.readObject();

        } catch (Exception e) {

            throw e;

        } finally {

            ois.close();

        }

        return key;

    }

}

运行结果：

准备用公钥加密的字符串为：深圳,您好!

用公钥加密后的结果为:Ep2Y6EstlUWQnmVxsZ0/NIV1NFIPAlg8rJguRdQB+2uBD+/sunrPiVoCm3zbuj317CNG5hwijNBf

qKETmd7HoftpnHxzYwn+lWqlVdUHIO+ZrFn2OB6omlA/aFHCZzIHtKDU72cNuiBiwONxCXyaWq4Z

scDfvzbz3//UYOhlDs4=

用私钥解密后的字符串为：深圳,您好!

码农公寓

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