java中加密算法AES和RSA

一、简介

对于机密信息，我们需要加密，这里介绍加密算法在java中的使用。

二、知识点

目前常用的加密算法有对称加密算法与非对称加密算法。

2.1 对称加密算法

在对称加密中，加密方与解密方都共用同一个**，也就是加密与解密的**是一样的。
特点：

• 通常它的算法公开，加解密速度快。现在常用的AES算法，即advanced encrytion standard，

• **长度，目前可用的是128位。

• 加密的原文长度不限。

2.2 非对称加密

非对称加密，又称公开**加密，它有两个**，公钥（public key）和私钥（private key），它们是不同的。公钥与私钥是配对使用的，使用公钥加密时，只有对应的私钥才能解开；用私钥加密时，只有对应的公钥才能解开。
特点：

• 通常是接收方先生成一对**，即公钥和私钥，然后公钥公开，发送方用公开的公钥加密，密方传给接收方，然后接收方用私钥解密。

• 非对称加密没有对称加密速度快，常用的是RSA算法。

• RSA通常加密原文较小的串，串越大，******.initialize(n)的n值就相应增大，加密解密速度越慢；

三、实例

3.1 添加base64的maven依赖

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.10</version>
</dependency>

3.2 对称加密AES代码实例

public class AESMain {
    public static void main(String[] args) throws Exception {
        String source = "study hard and make progress everyday";
        System.out.println("message source : "+source);

        /********** **生成方式一： 自动生成**  **************/
        String keyStr = genKeyAES();  //生成**串
        System.out.println("AES keyStr : "+keyStr);
        SecretKey key = loadKeyAES(keyStr);  //根据**串获取**

//        /**********  **生成方式二： 指定种子(或者可以说是密码)生成** ***********/
//        String password = "123456";
//        SecretKey key = genRawKeyAES(password);  //根据password获取**
//        String keyStr = Base64.encodeBase64String(key.getEncoded());  //生成**串
//        System.out.println("AES keyStr : "+keyStr);
//
        String encryptStr = encryptAES(source,key);  //AES加密
        System.out.println("AES encrypt result : " + encryptStr);

        String deencryptStr = deencryptAES(encryptStr,key);  //AES解密
        System.out.println("AES deencrypt result : " +deencryptStr);

    }

    //生成**串
    static String genKeyAES() throws Exception {
        KeyGenerator ****** = KeyGenerator.getInstance("AES");
        ******.init(128);
        SecretKey key = ******.generateKey();
        String keyStr = Base64.encodeBase64String(key.getEncoded());
        return keyStr;
    }

    //根据password生成**串
    static String genKeyAES(String password) throws Exception {
        SecretKey key = genRawKeyAES(password);
        String keyStr = Base64.encodeBase64String(key.getEncoded());
        return keyStr;
    }

    //根据password生成原始**串
    static SecretKey genRawKeyAES(String password) throws Exception {
        KeyGenerator ****** = KeyGenerator.getInstance("AES");
        ******.init(128,new SecureRandom(password.getBytes("utf8")));
        SecretKey key = ******.generateKey();
        return key;
    }

    //根据**串获取**
    static SecretKey loadKeyAES(String keyStr) throws Exception {
        SecretKey key = new SecretKeySpec(Base64.decodeBase64(keyStr), "AES");
        return key;
    }

    //AES加密
    static String encryptAES(String source, SecretKey key) throws Exception {
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] result = cipher.doFinal(source.getBytes("utf8"));
        return Base64.encodeBase64String(result);
    }

    //AES解密
    static String deencryptAES(String source, SecretKey key) throws Exception {
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] resultByte = cipher.doFinal(Base64.decodeBase64(source));
        String result = new String(resultByte,"utf-8");
        return result;
    }
}

运行结果：

message source : study hard and make progress everyday
AES keyStr : evD5UdP8LK8UrfrmxGQheA==
AES encrypt result : 1z8zSWmRRFPNb6qoURgFp1c778SzaDqbErrVroDthM5eBXrQTFevAzYmRStK7EPZ
AES deencrypt result : study hard and make progress everyday

3.3 非对称加密算法RSA代码实例

public class RSAMain {
    public static void main(String[] args) throws Exception {
        String source = "study hard and make progress everyday";
        System.out.println("message source : "+source);

        KeyPair keyPair = getKeyPair();  //生成**对
        String pubKeyStr = getPubKey(keyPair); //获取公钥串
        System.out.println("pubKeyStr : "+pubKeyStr);
        String priKeyStr = getPriKey(keyPair); //获取私钥串
        System.out.println("priKeyStr : "+priKeyStr);

        PublicKey pubKey = loadPubKey(pubKeyStr);//加载公钥
        PrivateKey priKey = loadPriKey(priKeyStr);//加载私钥

        /**************** 公钥加密 私钥解密********************/
        System.out.println("\n/**************** 公钥加密 私钥解密********************/");
        String encryptStr = pubEncrypt(source,pubKey);  //RSA加密
        System.out.println("RSA pubKey encrypt result : " + encryptStr);
        String decryptStr = priDecrypt(encryptStr,priKey);  //RSA解密
        System.out.println("RSA priKey decryptStr result : " +decryptStr);

        /**************** 私钥加密 公钥解密********************/
        System.out.println("\n/**************** 私钥加密 公钥解密********************/");
        encryptStr = priEncrypt(source,priKey);  //RSA加密
        System.out.println("RSA priKey encrypt result : " + encryptStr);
        decryptStr = pubDecrypt(encryptStr,pubKey);  //RSA解密
        System.out.println("RSA pubKey decryptStr result : " +decryptStr);

    }

    //生成**对
    static KeyPair getKeyPair() throws Exception {
        KeyPairGenerator ****** = KeyPairGenerator.getInstance("RSA");
        ******.initialize(512); //可以理解为：加密后的密文长度，实际原文要小些 越大 加密解密越慢
        KeyPair keyPair = ******.generateKeyPair();
        return keyPair;
    }

    //获取公钥Base64字符串
    static String getPubKey(KeyPair keyPair){
        PublicKey key = keyPair.getPublic();
        return Base64.encodeBase64String(key.getEncoded());
    }

    //获取私钥Base64字符串
    static String getPriKey(KeyPair keyPair){
        PrivateKey key = keyPair.getPrivate();
        return Base64.encodeBase64String(key.getEncoded());
    }

    //根据公钥串获取公钥
    static PublicKey loadPubKey(String keyStr) throws Exception {
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.decodeBase64(keyStr));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey key = keyFactory.generatePublic(keySpec);
        return key;
    }

    //根据私钥串获取私钥
    static PrivateKey loadPriKey(String keyStr) throws Exception {
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(keyStr));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey key = keyFactory.generatePrivate(keySpec);
        return key;
    }

    /**************** 公钥加密 私钥解密********************/
    //使用公钥加密
    static String pubEncrypt(String source,PublicKey key) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE,key);
        return Base64.encodeBase64String(cipher.doFinal(source.getBytes("utf8")));
    }

    //使用私钥解密
    static String priDecrypt(String source,PrivateKey key) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE,key);
        return new String(cipher.doFinal(Base64.decodeBase64(source)),"utf8");
    }




    /**************** 私钥加密 公钥解密********************/
    //使用私钥加密
    static String priEncrypt(String source,PrivateKey key) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE,key);
        return Base64.encodeBase64String(cipher.doFinal(source.getBytes("utf8")));
    }

    //使用公钥解密
    static String pubDecrypt(String source,PublicKey key) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE,key);
        return new String(cipher.doFinal(Base64.decodeBase64(source)),"utf8");
    }
}

运行结果：

message source : study hard and make progress everyday
pubKeyStr : M2wwDQYJKoZIhvcNAQEBBQADSwAwSAJBAItWYa39aUhRTIXEIBCSfSCp9CvXj/k9STtMv7y5OVD9ILArIf8ZwU+qepahkO40EUJ37IBS3ciiTw7CcS7U7UsCAwEAAQ==
priKeyStr : M2IBUwIBADANBgkqhkiG9w0BAQEFAASCAT0wggE5AgEAAkEAi1Zhrf1pSFFMhcQgEJJ9IKn0K9eP+T1JO0y/vLk5UP0gsCsh/xnBT6p6lqGQ7jQRQnfsgFLdyKJPDsJxLtTtSwIDAQABAkBeSJNMIl9tWeXH1hBEZntY8OeSCwkXA8tb3vEXCNap37p06hj5d2gqaK/ZkgBqVfY6keCcRqbkOROyxdfCQTjBAiEA49WvON+HhlApKXHhHglz9bmpu+LLp6NGDicTLszfGLECIQCckAMKaWcn8u1V+svGbIBHxiKI+QUBXbbo6sUZt/UkuwIgEDpcLLTfNlXnWKhf3H/X3pzG1jclQl+C0ec+morFKUECIE5CMjLnIvg2FuqOdYOWwrydzq93Akh/hqmAiMtlR7V3AiBVblFmuDimgKb8OWg+2BaWTuKZA/BG9Z8nsT2tqaNuSA==



/**************** 公钥加密 私钥解密********************/
RSA pubKey encrypt result : do1DUKBnm9J49+IhFDqPEI53tGX69kPfPbqYsPPEabm9NYTvNiEEUzjT5w1j1yQtxlz7T2n6QyHKHv0BjZOoqg==
RSA priKey decryptStr result : study hard and make progress everyday



/**************** 私钥加密 公钥解密********************/
RSA priKey encrypt result : S6bEfnsciTRNmdqe3mh9LBUsyYS5Qff6nj2xRxaiyhi2/Frw17snIZfB0rOTSnu7JjamjLZozaJ/WlwdEFcloA==
RSA pubKey decryptStr result : study hard and make progress everyday