【RSA】java-DEMO练习

package com.zcw.rsa;

import java.io.ByteArrayOutputStream;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;

/**
 * @ClassName : TestRSA
 * @Description : 进行RSA加解密练习
 * @Author : Zhaocunwei
 * @Date: 2020-04-24 10:50
 */
public class TestRSA {
    /**
     * RSA最大加密明文大小
    */
private static final int MAX_ENCRYPT_BLOCK = 117;

    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;

    /**
     * 获取密钥对
     *
     * @return 密钥对
     */
    public static KeyPair getKeyPair() throws Exception {
        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
        generator.initialize(1024);
        return generator.generateKeyPair();
    }

    /**
     * 获取私钥
     *
     * @param privateKey 私钥字符串
     * @return
     */
    public static PrivateKey getPrivateKey(String privateKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
        return keyFactory.generatePrivate(keySpec);
    }

    /**
     * 获取公钥
     *
     * @param publicKey 公钥字符串
     * @return
     */
    public static PublicKey getPublicKey(String publicKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
        return keyFactory.generatePublic(keySpec);
    }

    /**
     * RSA加密
     *
     * @param data 待加密数据
     * @param publicKey 公钥
     * @return
     */
    public static String encrypt(String data, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        int inputLen = data.getBytes().length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offset = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offset > 0) {
            if (inputLen - offset > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data.getBytes(), offset, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data.getBytes(), offset, inputLen - offset);
            }
            out.write(cache, 0, cache.length);
            i++;
            offset = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        // 获取加密内容使用base64进行编码,并以UTF-8为标准转化成字符串
        // 加密后的字符串
        return new String(Base64.encodeBase64String(encryptedData));
    }

    /**
     * RSA解密
     *
     * @param data 待解密数据
     * @param privateKey 私钥
     * @return
     */
    public static String decrypt(String data, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] dataBytes = Base64.decodeBase64(data);
        int inputLen = dataBytes.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offset = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offset > 0) {
            if (inputLen - offset > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
            }
            out.write(cache, 0, cache.length);
            i++;
            offset = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        // 解密后的内容
        return new String(decryptedData, "UTF-8");
    }

    /**
     * 签名
     *
     * @param data 待签名数据
     * @param privateKey 私钥
     * @return 签名
     */
    public static String sign(String data, PrivateKey privateKey) throws Exception {
        byte[] keyBytes = privateKey.getEncoded();
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey key = keyFactory.generatePrivate(keySpec);
        Signature signature = Signature.getInstance("MD5withRSA");
        signature.initSign(key);
        signature.update(data.getBytes());
        return new String(Base64.encodeBase64(signature.sign()));
    }

    /**
     * 验签
     *
     * @param srcData 原始字符串
     * @param publicKey 公钥
     * @param sign 签名
     * @return 是否验签通过
     */
    public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {
        byte[] keyBytes = publicKey.getEncoded();
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey key = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance("MD5withRSA");
        signature.initVerify(key);
        signature.update(srcData.getBytes());
        return signature.verify(Base64.decodeBase64(sign.getBytes()));
    }

    public static void main(String[] args) {
        try {
            // 生成密钥对
            KeyPair keyPair = getKeyPair();
            String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
            String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
            System.out.println("私钥:" + privateKey);
            System.out.println("公钥:" + publicKey);
            // RSA加密
            String data = "需要加密的内容";
            String encryptData = encrypt(data, getPublicKey(publicKey));
            System.out.println("加密后内容:" + encryptData);
            // RSA解密
            String decryptData = decrypt(encryptData, getPrivateKey(privateKey));
            System.out.println("解密后内容:" + decryptData);

            // RSA签名
            String sign = sign(data, getPrivateKey(privateKey));
            // RSA验签
            boolean result = verify(data, getPublicKey(publicKey), sign);
            System.out.print("验签结果:" + result);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.print("加解密异常");
        }
    }
}

运行结果：

私钥: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
公钥:MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDG2gq3GHMRKH20wjTGUF/AXtvV4GrWOgFZGKC58nB7y6OtzR5u28lmld0eIHa9STsLV0kvRidWvFjCmS8zZYFpVBL0XJjFavIUHV6IC+K+RlRJbhmXWeBU041efZttzIu12dbBUuzLC/r2s/gmeE7otrN5IDAgEHLdx4UkMtkgAwIDAQAB
加密后内容:wQyPXFHnQAXF5aiwXkZGXdHbRmvvf6XoOoRc7Cc9sWx/i/RLUzlk3p8BXlSdmJKvaV4SzfH8vLhu/FmfYYoeg/SP2VIk5oECihBIw8YleNo+lo8zA5krsnI6XsrCRVIPEkdWFLupZ4rAePgIJOpQWl9s6jctsZ05As5U6UGsNV8=
解密后内容:需要加密的内容
验签结果:trueDisconnected from the target VM, address: '127.0.0.1:55631', transport: 'socket'```