RAS非对称加密

加解密密钥不一致，一般私钥不公开，使用公钥加密，私钥解密，使用私钥加密，公钥可以解密。

java代码

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class RSA {
    //非对称密钥算法
    private static final String KEY_ALGORITHM = "RSA";
    //密钥长度，在512到65536位之间，建议不要太长，否则速度很慢，生成的加密数据很长
    private static final int KEY_SIZE = 512;
    //字符编码
    private static final String CHARSET = "UTF-8";

    /**
     * 生成密钥对
     *
     * @return KeyPair 密钥对
     */
    public static KeyPair getKeyPair() throws Exception {
        return getKeyPair(null);
    }

    /**
     * 生成密钥对
     * @param password 生成密钥对的密码
     * @return
     * @throws Exception
     */
    public static KeyPair getKeyPair(String password) throws Exception {
        //实例化密钥生成器
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        //初始化密钥生成器
        if(password == null){
            keyPairGenerator.initialize(KEY_SIZE);
        }else {
            SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
            secureRandom.setSeed(password.getBytes(CHARSET));
            keyPairGenerator.initialize(KEY_SIZE, secureRandom);
        }
        //生成密钥对
        return keyPairGenerator.generateKeyPair();
    }

    /**
     * 取得私钥
     *
     * @param keyPair 密钥对
     * @return byte[] 私钥
     */
    public static byte[] getPrivateKeyBytes(KeyPair keyPair) {
        return keyPair.getPrivate().getEncoded();
    }

    /**
     * 取得Base64编码的私钥
     *
     * @param keyPair 密钥对
     * @return String Base64编码的私钥
     */
    public static String getPrivateKey(KeyPair keyPair) {
        return Base64.getEncoder().encodeToString(getPrivateKeyBytes(keyPair));
    }

    /**
     * 取得公钥
     *
     * @param keyPair 密钥对
     * @return byte[] 公钥
     */
    public static byte[] getPublicKeyBytes(KeyPair keyPair) {
        return keyPair.getPublic().getEncoded();
    }

    /**
     * 取得Base64编码的公钥
     *
     * @param keyPair 密钥对
     * @return String Base64编码的公钥
     */
    public static String getPublicKey(KeyPair keyPair) {
        return Base64.getEncoder().encodeToString(getPublicKeyBytes(keyPair));
    }

    /**
     * 私钥加密
     *
     * @param data       待加密数据
     * @param privateKey 私钥字节数组
     * @return byte[] 加密数据
     */
    public static byte[] encryptByPrivateKey(byte[] data, byte[] privateKey) throws Exception {
        //实例化密钥工厂
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        //生成私钥
        PrivateKey key = keyFactory.generatePrivate(new PKCS8EncodedKeySpec(privateKey));
        //数据加密
        Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(data);
    }

    /**
     * 私钥加密
     *
     * @param data       待加密数据
     * @param privateKey Base64编码的私钥
     * @return String Base64编码的加密数据
     */
    public static String encryptByPrivateKey(String data, String privateKey) throws Exception {
        byte[] key = Base64.getDecoder().decode(privateKey);
        return Base64.getEncoder().encodeToString(encryptByPrivateKey(data.getBytes(CHARSET), key));
    }

    /**
     * 公钥加密
     *
     * @param data      待加密数据
     * @param publicKey 公钥字节数组
     * @return byte[] 加密数据
     */
    public static byte[] encryptByPublicKey(byte[] data, byte[] publicKey) throws Exception {
        //实例化密钥工厂
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        //生成公钥
        PublicKey key = keyFactory.generatePublic(new X509EncodedKeySpec(publicKey));
        //数据加密
        Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(data);
    }

    /**
     * 公钥加密
     *
     * @param data      待加密数据
     * @param publicKey Base64编码的公钥
     * @return String Base64编码的加密数据
     */
    public static String encryptByPublicKey(String data, String publicKey) throws Exception {
        byte[] key = Base64.getDecoder().decode(publicKey);
        return Base64.getEncoder().encodeToString(encryptByPublicKey(data.getBytes(CHARSET), key));
    }

    /**
     * 私钥解密
     *
     * @param data       待解密数据
     * @param privateKey 私钥字节数组
     * @return byte[] 解密数据
     */
    public static byte[] decryptByPrivateKey(byte[] data, byte[] privateKey) throws Exception {
        //实例化密钥工厂
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        //生成私钥
        PrivateKey key = keyFactory.generatePrivate(new PKCS8EncodedKeySpec(privateKey));
        //数据解密
        Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(data);
    }

    /**
     * 私钥解密
     *
     * @param data       Base64编码的待解密数据
     * @param privateKey Base64编码的私钥
     * @return String 解密数据
     */
    public static String decryptByPrivateKey(String data, String privateKey) throws Exception {
        byte[] key = Base64.getDecoder().decode(privateKey);
        return new String(decryptByPrivateKey(Base64.getDecoder().decode(data), key), CHARSET);
    }

    /**
     * 公钥解密
     *
     * @param data      待解密数据
     * @param publicKey 公钥字节数组
     * @return byte[] 解密数据
     */
    public static byte[] decryptByPublicKey(byte[] data, byte[] publicKey) throws Exception {
        //实例化密钥工厂
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        //产生公钥
        PublicKey key = keyFactory.generatePublic(new X509EncodedKeySpec(publicKey));
        //数据解密
        Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(data);
    }

    /**
     * 公钥解密
     *
     * @param data      Base64编码的待解密数据
     * @param publicKey Base64编码的公钥
     * @return String 解密数据
     */
    public static String decryptByPublicKey(String data, String publicKey) throws Exception {
        byte[] key = Base64.getDecoder().decode(publicKey);
        return new String(decryptByPublicKey(Base64.getDecoder().decode(data), key), CHARSET);
    }

    /**
     * 测试加解密方法
     *
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        //生成密钥对，一般生成之后可以放到配置文件中
        KeyPair keyPair = RSA.getKeyPair();
        //公钥
        String publicKey = RSA.getPublicKey(keyPair);
        //私钥
        String privateKey = RSA.getPrivateKey(keyPair);

        System.out.println("公钥：\n" + publicKey);
        System.out.println("私钥：\n" + privateKey);

        String data = "RSA 加密解密测试!";
        {
            System.out.println("\n===========私钥加密，公钥解密==============");
            String s1 = RSA.encryptByPrivateKey(data, privateKey);
            System.out.println("加密后的数据:" + s1);
            String s2 = RSA.decryptByPublicKey(s1, publicKey);
            System.out.println("解密后的数据:" + s2 + "\n\n");
        }

        {
            System.out.println("\n===========公钥加密，私钥解密==============");
            String s1 = RSA.encryptByPublicKey(data, publicKey);
            System.out.println("加密后的数据:" + s1);
            String s2 = RSA.decryptByPrivateKey(s1, privateKey);
            System.out.println("解密后的数据:" + s2 + "\n\n");
        }

    }
}

js代码   依赖 jsencrypt 项目

<script src="bin/jsencrypt.min.js"></script>
<script type="text/javascript">
    var encrypt = new JSEncrypt();
    encrypt.setPublicKey('java生成的公钥');//后台给
    var encrypted = encrypt.encrypt('加密的字符串');
</script>