JAVA RSA密钥对的生成与验证

太过爱你忘了你带给我的痛 2022-04-11 09:08 230阅读 0赞

在上一篇《Java&keytool生成RSA密钥》中，我们用keytool先生成密钥库和公钥证书，然后通过代码方式获得文件和BASE64串形式的公私密钥对，而其实根本无这么复杂，可直接通过JAVA代码获得公私密钥对。代码如下：

package com.bijian.test;
    
    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
        * @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();
            }
        }
    
        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);
        }
    }

运行结果：

![5405c223-b075-38c3-9719-50a1840a8250.png][]  
        用上一篇验证公私钥对加签验签、加解密的代码验证，也都是OK的。附上加解密验证的代码如下。

package com.bijian.test;
    
    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 RSAUtil {
        
        /** 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 = "你好nihao";// 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：

![d3ace1d5-8cd5-39b6-92aa-4e5045bd25ec.png][]

附阿里生成公私钥的链接：[https://docs.open.alipay.com/291/105971][https_docs.open.alipay.com_291_105971]

[5405c223-b075-38c3-9719-50a1840a8250.png]: /images/20220411/d62effb5632347ef8d9cd9488db0ed11.png
[d3ace1d5-8cd5-39b6-92aa-4e5045bd25ec.png]: /images/20220411/71733f6368b44d3bbdbaef94d7a0e78c.png
[https_docs.open.alipay.com_291_105971]: https://docs.open.alipay.com/291/105971