Java非对称加密解密

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另外https://www.jianshu.com/p/048be4864559 写得挺好

import lombok.Data;

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

public class SignatureUtil {

    /**
     * 生成公钥和私钥
     *
     * @return
     * @throws NoSuchAlgorithmException
     */
    public static Keys generateKey() throws NoSuchAlgorithmException {
        Keys resultMap = new Keys();
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        Base64.Encoder encoder = Base64.getEncoder();
        resultMap.setPrivateKey(encoder.encodeToString(keyPair.getPrivate().getEncoded()));
        resultMap.setPublicKey(encoder.encodeToString(keyPair.getPublic().getEncoded()));
        return resultMap;
    }

    /**
     * RSA加密-pub-en,pri-de
     *
     * @param key
     * @param content
     * @return
     * @throws Exception
     */
    public static String rsaEncrypt(String key, String content) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, keyFactory.generatePublic(new X509EncodedKeySpec(Base64.getDecoder().decode(key))));
        byte[] bytes = cipher.doFinal(content.getBytes());
        return Base64.getEncoder().encodeToString(bytes);
    }

    /**
     * RSA解密-pub-en,pri-de
     *
     * @param key
     * @param content
     * @return
     * @throws Exception
     */
    public static String rsaDecrypt(String key, String content) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, keyFactory.generatePrivate(new PKCS8EncodedKeySpec(Base64.getDecoder().decode(key))));
        byte[] bytes = cipher.doFinal(Base64.getDecoder().decode(content));
        return new String(bytes);
    }

    /**
     * RSA加密-pri-en,pub-de
     *
     * @param key
     * @param content
     * @return
     * @throws Exception
     */
    public static String rsaEncryptReverse(String key, String content) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, keyFactory.generatePrivate(new PKCS8EncodedKeySpec(Base64.getDecoder().decode(key))));
        byte[] bytes = cipher.doFinal(content.getBytes());
        return Base64.getEncoder().encodeToString(bytes);
    }

    /**
     * RSA解密-pri-en,pub-de
     *
     * @param key
     * @param content
     * @return
     * @throws Exception
     */
    public static String rsaDecryptReverse(String key, String content) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, keyFactory.generatePublic(new X509EncodedKeySpec(Base64.getDecoder().decode(key))));
        byte[] bytes = cipher.doFinal(Base64.getDecoder().decode(content));
        return new String(bytes);
    }

    /**
     * 私钥签名
     *
     * @param privateKeyStr
     * @param content
     * @return
     * @throws Exception
     */
    public static String generateSignature(String privateKeyStr, String content) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        Signature signature = Signature.getInstance("SHA1withRSA");
        PrivateKey privateKey = keyFactory.generatePrivate(new PKCS8EncodedKeySpec(Base64.getDecoder().decode(privateKeyStr)));
        signature.initSign(privateKey);
        signature.update(content.getBytes());
        return Base64.getEncoder().encodeToString(signature.sign());
    }

    /**
     * 公钥验证
     *
     * @param publicKeyStr
     * @param content
     * @param sign
     * @return
     * @throws Exception
     */
    public static boolean verifySignature(String publicKeyStr, String content, String sign) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        Signature signature = Signature.getInstance("SHA1withRSA");
        PublicKey publicKey = keyFactory.generatePublic(new X509EncodedKeySpec(Base64.getDecoder().decode(publicKeyStr)));
        signature.initVerify(publicKey);
        signature.update(content.getBytes());
        return signature.verify(Base64.getDecoder().decode(sign));
    }

    public static void main(String[] args) throws Exception {
        String content = "大王叫我来巡山呐";

        //生成密钥对
        Keys keys = generateKey();

        //公钥加密，私钥解密
        String publicKeyData = rsaEncrypt(keys.publicKey, content);
        System.out.println("公钥加密：" + publicKeyData);
        System.out.println("私钥解密：" + rsaDecrypt(keys.privateKey, publicKeyData));

        //私钥加密，公钥解密
        String privateKeyData = rsaEncryptReverse(keys.privateKey, content);
        System.out.println("私钥加密：" + privateKeyData);
        System.out.println("公钥解密：" + rsaDecryptReverse(keys.publicKey, privateKeyData));


        //私钥签名
        String sign = generateSignature(keys.privateKey, content);
        System.out.println("私钥签名：" + sign);

        //公钥验证
        boolean verifyResult = verifySignature(keys.publicKey, content, sign);
        System.out.println("公钥验证：" + verifyResult);

        //将内容做下修改，再进行公钥验证
        boolean verifyResult2 = verifySignature(keys.publicKey, content + "啦啦啦啦", sign);
        System.out.println("公钥验证：" + verifyResult2);
    }

    @Data
    public static class Keys {
        public String publicKey;
        public String privateKey;
    }
}