Java实现RSA加密与解密

Leefs 2020-02-29 AM 3653℃ 0条

# Java实现RSA加密与解密

### 前言

之前没有做过关于RSA加解密的对接，今天做的时候踩到一些坑今天整理一下。

### 踩坑记录

当拿到私钥以后先打开看一下头部的加密方式：

![Java实现RSA加密与解密01.png][1]

一般Java都是通过PKCS8的加密方式对文件进行解密的，网上找到的工具类也都是针对PKCS8进行解密，但是一般原始的文件都是通过PKCS1方式进行加密

如果可以接触到正式环境的Linux系统可以执行如下命令：

**pkcs1私钥转pkcs8私钥：**

```
openssl pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt
```

如果接触Linux不能轻易修改可以使用如下工具类：

```java
import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.security.KeyFactory;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class Main {
    public static String pkcs1_public = "" +
            "MIGJAoGBAK3m6BabZZ2qQwjmIOBOZ1q9g9OnqGapuinLs3182ew2LAQT62iLReBC\n" +
            "NB64TRh/tU4iIIjx5bNRpNZ8IrcP92YVNuxMrdSCqXpC5gpGFKf1CfG0SrO+TPmO\n" +
            "/d1zexJq/yArc7HbYMFZRfks7BjnaQGJ5rCVEVyS/y+0I5hU+t37AgMBAAE=\n";
    public static String pkcs1_private = "" +
            "MIICWwIBAAKBgQCt5ugWm2WdqkMI5iDgTmdavYPTp6hmqbopy7N9fNnsNiwEE+to\n" +
            "i0XgQjQeuE0Yf7VOIiCI8eWzUaTWfCK3D/dmFTbsTK3Ugql6QuYKRhSn9QnxtEqz\n" +
            "vkz5jv3dc3sSav8gK3Ox22DBWUX5LOwY52kBieawlRFckv8vtCOYVPrd+wIDAQAB\n" +
            "AoGAR7qukGSYjWflLo59kQfF6c+xyGOnOnFXsFWtO118JcpSbXwp5X1M3StxhBpQ\n" +
            "8oH6rre048ejD0vlyfJ5/zg+utZ0V2x5xM4DxBTyZifdujZGac9dzsfZ/CO6NS1s\n" +
            "HblrMTnm5EiousPH1lywmhGce7LVfMR76mVAFZTpHScHLAECQQDY+sL4hs8v578j\n" +
            "nhURLS5bwvih4wVbajPsN7oiswEsjCYymDO8IywL4l9Pkvfxd4d3dh6BhsYfB2W8\n" +
            "2ItBaWdBAkEAzSz0D2zJGC/x5DN5At1NnmxSpMfqo6e3L9vMHe7T5mepsRwPIobQ\n" +
            "DQrdBdCeBd30qVi1lw7NmMPKEflIxo2SOwJAbotLO+0Kr4BlPBM07nxTSwLJQ0jz\n" +
            "GMDB1U4K8dS6+2Qnrc0nRmmw7hkVr+fTlFzuUmmGXz03wOU26wBz6g52QQJASUVA\n" +
            "czG6LrUQgRoQoQE+8tBkQwxRstf2B1VK83WSnrluVB1dGktiiQXUIHt7s0SsVr2j\n" +
            "O6rBqUhiJUEMyDtOeQJAb5DnL8q5FbPkZg82LilKBtMyI5iGYnXGkz9adp4Kgpf0\n" +
            "V5dXr1QJl3rdurgz5BbZjhrxU54GTFnm/izIoaAU2g==\n";
    public static String pkcs8_public = "" +
            "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCt5ugWm2WdqkMI5iDgTmdavYPT\n" +
            "p6hmqbopy7N9fNnsNiwEE+toi0XgQjQeuE0Yf7VOIiCI8eWzUaTWfCK3D/dmFTbs\n" +
            "TK3Ugql6QuYKRhSn9QnxtEqzvkz5jv3dc3sSav8gK3Ox22DBWUX5LOwY52kBieaw\n" +
            "lRFckv8vtCOYVPrd+wIDAQAB\n";
    public static String pkcs8_private = "" +
            "MIICdQIBADANBgkqhkiG9w0BAQEFAASCAl8wggJbAgEAAoGBAK3m6BabZZ2qQwjm\n" +
            "IOBOZ1q9g9OnqGapuinLs3182ew2LAQT62iLReBCNB64TRh/tU4iIIjx5bNRpNZ8\n" +
            "IrcP92YVNuxMrdSCqXpC5gpGFKf1CfG0SrO+TPmO/d1zexJq/yArc7HbYMFZRfks\n" +
            "7BjnaQGJ5rCVEVyS/y+0I5hU+t37AgMBAAECgYBHuq6QZJiNZ+Uujn2RB8Xpz7HI\n" +
            "Y6c6cVewVa07XXwlylJtfCnlfUzdK3GEGlDygfqut7Tjx6MPS+XJ8nn/OD661nRX\n" +
            "bHnEzgPEFPJmJ926NkZpz13Ox9n8I7o1LWwduWsxOebkSKi6w8fWXLCaEZx7stV8\n" +
            "xHvqZUAVlOkdJwcsAQJBANj6wviGzy/nvyOeFREtLlvC+KHjBVtqM+w3uiKzASyM\n" +
            "JjKYM7wjLAviX0+S9/F3h3d2HoGGxh8HZbzYi0FpZ0ECQQDNLPQPbMkYL/HkM3kC\n" +
            "3U2ebFKkx+qjp7cv28wd7tPmZ6mxHA8ihtANCt0F0J4F3fSpWLWXDs2Yw8oR+UjG\n" +
            "jZI7AkBui0s77QqvgGU8EzTufFNLAslDSPMYwMHVTgrx1Lr7ZCetzSdGabDuGRWv\n" +
            "59OUXO5SaYZfPTfA5TbrAHPqDnZBAkBJRUBzMboutRCBGhChAT7y0GRDDFGy1/YH\n" +
            "VUrzdZKeuW5UHV0aS2KJBdQge3uzRKxWvaM7qsGpSGIlQQzIO055AkBvkOcvyrkV\n" +
            "s+RmDzYuKUoG0zIjmIZidcaTP1p2ngqCl/RXl1evVAmXet26uDPkFtmOGvFTngZM\n" +
            "Web+LMihoBTa\n";

public static void main(String[] args) throws Exception {
        System.out.println(private_decrypt(public_encrypt("PKCS#8公钥加密，PKCS#8私钥解密", pkcs8_public), pkcs8_private));
        System.out.println(public_decrypt(private_encrypt("PKCS#8私钥加密，PKCS#8公钥解密", pkcs8_private), pkcs8_public));
        //System.out.println(private_decrypt(public_encrypt("PKCS#8公钥加密，PKCS#1私钥解密",pkcs8_public),pkcs1_private));
        //System.out.println(private_decrypt(public_encrypt("PKCS#1公钥加密，PKCS#8私钥解密",pkcs1_public),pkcs8_private));
        //System.out.println(private_decrypt(public_encrypt("PKCS#1公钥加密，PKCS#1私钥解密",pkcs1_public),pkcs1_private));
        //System.out.println(public_decrypt(private_encrypt("PKCS#1私钥加密，PKCS#8公钥解密",pkcs1_private),pkcs8_public));
        //System.out.println(public_decrypt(private_encrypt("PKCS#8私钥加密，PKCS#1公钥解密",pkcs8_private),pkcs1_public));
        //System.out.println(public_decrypt(private_encrypt("PKCS#1私钥加密，PKCS#1公钥解密",pkcs1_private),pkcs1_public));
    }

public static String public_encrypt(String str, String publicKey) throws Exception {
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        return outStr;
    }

public static String private_encrypt(String str, String privateKey) throws Exception {
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, priKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        return outStr;
    }

public static String private_decrypt(String str, String privateKey) throws Exception {
        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }

public static String public_decrypt(String str, String publicKey) throws Exception {
        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, pubKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }
}
```

工具类中包含了PKCS#1和PKCS#8之间各种情况的相互转换。相信总有一个满足你的需求。

### 今天RSA密钥解密又碰见一个坑

通过上面的工具类调用PKCS1私钥解密方法报如下错误

```java
Exception in thread "main" java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : algid parse error, not a sequence
	at sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(RSAKeyFactory.java:217)
	at java.security.KeyFactory.generatePrivate(KeyFactory.java:372)
	at com.mmit.common.RSAUtils.private_decrypt(RSAUtils.java:112)
	at com.mmit.common.RSAUtils.main(RSAUtils.java:82)
Caused by: java.security.InvalidKeyException: IOException : algid parse error, not a sequence
	at sun.security.pkcs.PKCS8Key.decode(PKCS8Key.java:351)
	at sun.security.pkcs.PKCS8Key.decode(PKCS8Key.java:356)
	at sun.security.rsa.RSAPrivateCrtKeyImpl.<init>(RSAPrivateCrtKeyImpl.java:91)
	at sun.security.rsa.RSAPrivateCrtKeyImpl.newKey(RSAPrivateCrtKeyImpl.java:75)
	at sun.security.rsa.RSAKeyFactory.generatePrivate(RSAKeyFactory.java:316)
	at sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(RSAKeyFactory.java:213)
	... 3 more
```

百度了上都是说**问题的原因是：rsa私钥的格式不是pksc8格式**，然而并不是。

在私钥解密时加上如下代码：

```java
java.security.Security.addProvider(
    new org.bouncycastle.jce.provider.BouncyCastleProvider()
);
```

问题解决方法

**附完整代码**

```java
public static String private_decrypt(String str, String privateKey) throws Exception {
    java.security.Security.addProvider(
        new org.bouncycastle.jce.provider.BouncyCastleProvider()
    );
    byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
    byte[] decoded = Base64.decodeBase64(privateKey);
    RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, priKey);
    String outStr = new String(cipher.doFinal(inputByte));
    return outStr;
}
```

[1]: https://lilinchao.com/usr/uploads/2020/03/2402510912.png

标签: Java工具类, RSA加解密

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