RSA2实例详解

本文介绍RSA2加密与解密，RSA2是RSA的加强版本，在密钥长度上采用2048, RSA2比RSA更安全，更可靠, 本人的另一篇文章RSA已经发表，有想了解的可以点开下面的RSA文章, 但RSA2在明文的加密数据长度上有个小缺陷，只能对不超过密文长度的明文进行加密

实例下载

工具集下载

RSA文章: http://www.wisdomdd.cn/Wisdom/resource/articleDetail.htm?resourceId=322

关于RSA2的理论其实与RSA类似，想具体了解的可以参考上面的链接,下面直接上代码

函数test1中使用RSA2的私钥对数据进行加密，使用RSA2的公钥对数据进行解密

下面代码中的密钥字符串是对密钥字节数组进行了base64加密而得到的，在使用时将密串进行base64解密即可

//私钥加密，公钥解密
public static void test1(String src){
    try {
        //1.初始化密钥
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(1024);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
         
        //String strPublicKey = Base64.encodeBase64String(rsaPublicKey.getEncoded());
        //String strPrivateKey = Base64.encodeBase64String(rsaPrivateKey.getEncoded());
         
        String strPublicKey = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAgdQVFyYvJQ38hBAEJ3Zr3BJFtp
         XauN83ghWtgJ1m92XvshGomjEgKpAxyQf9HqqvZB8U0nW+eNIgTAcKZemIQci/6/+oXMhu+WgdIxlJGLzvhZWa
         z7UzfKfCFTiUAh6X+hHRlPisekt/y70pbpkxd+GVbmVF5bGxSBnlhdnKa+lAbZd2sO8jv3fzSD0w3dWDmjKg9O
         jPxXt1jnwbj0BmwN4TDiMPSmmDBEz7JHadb6A99cswCVXWz3pgioHzq20ipDZDUdAphtgcyT6TO1eZdwHth1tw
         0UIcPfUmx5wMGSVBkP/42/AnvG8Y9ROwvg9XpCu2HI+o/n7Ljht5tknDKwIDAQAB";
          
        String strPrivateKey = "MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQCB1BUXJi8lDfy
          EEAQndmvcEkW2ldq43zeCFa2AnWb3Ze+yEaiaMSAqkDHJB/0eqq9kHxTSdb540iBMBwpl6YhByL/r/6hcyG75aB0j
          GUkYvO+FlZrPtTN8p8IVOJQCHpf6EdGU+Kx6S3/LvSlumTF34ZVuZUXlsbFIGeWF2cpr6UBtl3aw7yO/d/NIPTDd1YO
          aMqD06M/Fe3WOfBuPQGbA3hMOIw9KaYMETPskdp1voD31yzAJVdbPemCKgfOrbSKkNkNR0CmG2BzJPpM7V5l3Ae2HW3DRQh
          w99SbHnAwZJUGQ//jb8Ce8bxj1E7C+D1ekK7Ycj6j+fsuOG3m2ScMrAgMBAAECggEAEnDqkgA1gCDtdmDEBkr25SqfRmEg
          0VO7kbm8jGFPR+Lt2jBR75z8wa77s190H9AE28bicUaSSJ0oQ0RYwMMcPKPkRwRoiM1bngeg4+Rqkp37s9DdTZWie5lkoxk
          HRQnNcpLnXy63aSOiQnFbGj+eXDXpwOWXuRm1YdVz2cBm1U71Fy4pKNKU8B/Z/gLucnxotXWVQjhguKIrY0BEdH/0TJlPzl
          AQQYYuCItA7gJUNivCv0ecDswG0AchkdAIwbjRFS9Jpc4sWkvlgdYaP33uNjzXQrG7QZxSaCADorB8vFM/c7MxJZuS5hOvI
          ZN5FYTZJ7NW6ujepHaZKaPfexjYCQKBgQD6CIVP0I6jsqhLsqXr89x2hNqnvxhynfot3bGJzeGhuGYnAnfI/YzhekZ25mq
          dY5yYkTY2gWIgwf1f3HxEOY0ZuydTjrppkBnngGs2L03x2F+ZEnHYrg3DwUdahRxxqI/DyzKOUWUOt48ESaoMLUUFmdTrR7
          Bw5inS1WNhirv/XQKBgQCE7TfDTGe2O9CdKl6UGm6qFgXroWesBle5/2WDklVevo70xgOzKFtkVMbsRMb+9e6qZZbyCjDh6
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          MJwKBgH/nHfL/WAhLWyYmBBSYkb2bJpNLAQGY6KLP1oMM65Aj2TW5YHdTpN6vAx7NrdpHW5L8LYRiWUUylx+TlYn8+r4f
          6/UlfRyFF4tCORXlyvSdYAHY2p4iI25xD8QxdaR6uthIuNrurkiCA8oIuNEz0ywTTkTxTkPiqaBtgkIiixsNAoGAfk/8oTT
          FiMGmJvLQFORZLH7o+VPS9ADC9BfhGvm+7d0eczKG6YP79Icqz/E7N6PzOzB2E2HjuYlqJRxkGeUSXcvr7Rvljampd1W
          Y3qo8koDj8wlkOGzjOwMRL3kpikhZw285jZ9czu5ExW8wQYr0gERPpqLBcEnaCmwvYokATBkCgYEA1lPCbn8um4e7faqDV
          Ym0H6+2stYUHC4ucrmHw3FbvS4ko9omWMj5xyPDUP2x/Ls2AfJSZR9lqPty8yqDTObHiuEPv8q0e0qw+PJIp4kaY8tAFwc
          IXlphANJIeKgAmbfEYyboKzG8Qe+u5gA1gYKFl5zr/WZX0drqM5NG/CZzqfQ=";
         
        System.out.println("Public Key : " + strPublicKey); 
        System.out.println("Private Key : " + strPrivateKey); 
         
         
        //1.私钥加密加密
        byte[] keyPrivateBytes = Base64.decodeBase64(strPrivateKey);
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyPrivateBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(src.getBytes());
        System.out.println("私钥加密、公钥解密——加密 : " + Base64.encodeBase64String(result));
         
         
         
         
        //2.公钥解密
        byte[] keyPublicBytes = Base64.decodeBase64(strPublicKey);
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(keyPublicBytes);
        keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        result = cipher.doFinal(result);
        System.out.println("私钥加密、公钥解密——解密：" + new String(result));
         
         
    } catch (Exception e) {
        e.printStackTrace();
    }
}

注意:由于密钥长度的原因，明文的长度有一定的限制，如果明文数据太长的话，会报如下错误

javax.crypto.IllegalBlockSizeException: Data must not be longer than 245 bytes
    at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:337)
    at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:382)
    at javax.crypto.Cipher.doFinal(Cipher.java:2087)
    at com.wisdomdd.rsa2.RSA2Test.test2(RSA2Test.java:94)
    at com.wisdomdd.rsa2.RSA2Test.main(RSA2Test.java:118)

报错原因:

不管明文长度是多少，RSA 生成的密文长度总是固定的。

但是明文长度不能超过密钥长度。比如 Java 默认的 RSA 加密实现不允许明文长度超过密钥长度减去 11(单位是字节，也就是 byte)。也就是说，如果我们定义的密钥(我们可以通过 java.security.KeyPairGenerator.initialize(int keysize) 来定义密钥长度)长度为 1024(单位是位，也就是 bit)，生成的密钥长度就是 1024位 / 8位/字节 = 128字节，那么我们需要加密的明文长度不能超过 128字节 -

11 字节 = 117字节。也就是说，我们最大能将 117 字节长度的明文进行加密，否则会出问题(抛诸如 javax.crypto.IllegalBlockSizeException: Data must not be longer than 53 bytes 的异常)

http://www.wisdomdd.cn/Wisdom/resource/articleDetail.htm?resourceId=322 一文中在加密与解密时使用小技艺对加密与解密的字节进行拆份,解决明文长度太长的问题

函数test2中使用RSA2的公钥对数据进行加密，使用RSA2私钥对数据进行解密

public static void test2(String src){
    try {
        //1.初始化密钥
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(1024);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
         
        //String strPublicKey = Base64.encodeBase64String(rsaPublicKey.getEncoded());
        //String strPrivateKey = Base64.encodeBase64String(rsaPrivateKey.getEncoded());
         
        String strPublicKey = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAgdQVFyYvJQ38hBAEJ3Zr3BJ
         FtpXauN83ghWtgJ1m92XvshGomjEgKpAxyQf9HqqvZB8U0nW+eNIgTAcKZemIQci/6/+oXMhu+WgdIxlJGLzvhZWaz
         7UzfKfCFTiUAh6X+hHRlPisekt/y70pbpkxd+GVbmVF5bGxSBnlhdnKa+lAbZd2sO8jv3fzSD0w3dWDmjKg9OjPxXt
         1jnwbj0BmwN4TDiMPSmmDBEz7JHadb6A99cswCVXWz3pgioHzq20ipDZDUdAphtgcyT6TO1eZdwHth1tw0UIcPfUmx
         5wMGSVBkP/42/AnvG8Y9ROwvg9XpCu2HI+o/n7Ljht5tknDKwIDAQAB";
          
        String strPrivateKey = "MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQCB1BUXJi8lDfyEEAQndm
         vcEkW2ldq43zeCFa2AnWb3Ze+yEaiaMSAqkDHJB/0eqq9kHxTSdb540iBMBwpl6YhByL/r/6hcyG75aB0jGUkYvO+FlZrP
         tTN8p8IVOJQCHpf6EdGU+Kx6S3/LvSlumTF34ZVuZUXlsbFIGeWF2cpr6UBtl3aw7yO/d/NIPTDd1YOaMqD06M/Fe3WOfB
         uPQGbA3hMOIw9KaYMETPskdp1voD31yzAJVdbPemCKgfOrbSKkNkNR0CmG2BzJPpM7V5l3Ae2HW3DRQhw99SbHnAwZJUGQ
         //jb8Ce8bxj1E7C+D1ekK7Ycj6j+fsuOG3m2ScMrAgMBAAECggEAEnDqkgA1gCDtdmDEBkr25SqfRmEg0VO7kbm8jGFPR+
         Lt2jBR75z8wa77s190H9AE28bicUaSSJ0oQ0RYwMMcPKPkRwRoiM1bngeg4+Rqkp37s9DdTZWie5lkoxkHRQnNcpLnXy63
         aSOiQnFbGj+eXDXpwOWXuRm1YdVz2cBm1U71Fy4pKNKU8B/Z/gLucnxotXWVQjhguKIrY0BEdH/0TJlPzlAQQYYuCItA7g
         JUNivCv0ecDswG0AchkdAIwbjRFS9Jpc4sWkvlgdYaP33uNjzXQrG7QZxSaCADorB8vFM/c7MxJZuS5hOvIZN5FYTZJ7NW
         6ujepHaZKaPfexjYCQKBgQD6CIVP0I6jsqhLsqXr89x2hNqnvxhynfot3bGJzeGhuGYnAnfI/YzhekZ25mqdY5yYkTY2gW
         Igwf1f3HxEOY0ZuydTjrppkBnngGs2L03x2F+ZEnHYrg3DwUdahRxxqI/DyzKOUWUOt48ESaoMLUUFmdTrR7Bw5inS1WNh
         irv/XQKBgQCE7TfDTGe2O9CdKl6UGm6qFgXroWesBle5/2WDklVevo70xgOzKFtkVMbsRMb+9e6qZZbyCjDh6gO1xUVVMh
         YUBTxmLPdGdGmRVdEGDB2EonuRfhkImq1ftRID9LlstkUkQr70iwS+t7+f7H07fL6WOdiMkGbx/No/hze4RwuMJwKBgH/n
         HfL/WAhLWyYmBBSYkb2bJpNLAQGY6KLP1oMM65Aj2TW5YHdTpN6vAx7NrdpHW5L8LYRiWUUylx+TlYn8+r4f6/UlfRyFF4
         tCORXlyvSdYAHY2p4iI25xD8QxdaR6uthIuNrurkiCA8oIuNEz0ywTTkTxTkPiqaBtgkIiixsNAoGAfk/8oTTFiMGmJvLQ
         FORZLH7o+VPS9ADC9BfhGvm+7d0eczKG6YP79Icqz/E7N6PzOzB2E2HjuYlqJRxkGeUSXcvr7Rvljampd1WY3qo8koDj8w
         lkOGzjOwMRL3kpikhZw285jZ9czu5ExW8wQYr0gERPpqLBcEnaCmwvYokATBkCgYEA1lPCbn8um4e7faqDVYm0H6+2stYU
         HC4ucrmHw3FbvS4ko9omWMj5xyPDUP2x/Ls2AfJSZR9lqPty8yqDTObHiuEPv8q0e0qw+PJIp4kaY8tAFwcIXlphANJIeK
         gAmbfEYyboKzG8Qe+u5gA1gYKFl5zr/WZX0drqM5NG/CZzqfQ=";
         
        System.out.println("Public Key : " + strPublicKey); 
        System.out.println("Private Key : " + strPrivateKey); 
         
        System.out.println("加密前数据:" + src);
         
        //1.公钥加密
        byte[] keyPublicBytes = Base64.decodeBase64(strPublicKey);
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(keyPublicBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(src.getBytes());
        System.out.println("公钥加密、私钥解密——加密 : " + Base64.encodeBase64String(result));
         
        //2.私钥解密
        byte[] keyPrivateBytes = Base64.decodeBase64(strPrivateKey);
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyPrivateBytes);
        keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        result = cipher.doFinal(result);
        System.out.println("公钥加密、私钥解密——解密：" + new String(result));
    } catch (Exception e) {
        e.printStackTrace();
    }
}

公钥，私钥生成工具, 本文代码适用于 1024, 2048两种规则生成的密钥

实例代码中提供了公钥私钥生成工具

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