Java实现AES ECP PKCS5Padding加解密工具类

Posted 2021-02-20 yihuihui

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Java 实现一个AES/ECB/PKCS5Padding 加解密算法工具类

加密算法： AES
模式： ECB
补码方式： PKCS5Padding

1. 工具类

import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.Base64Utils;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.BufferedInputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.MessageDigest;

/**
 * Created by @author yihui in 19:12 20/1/2.
 */
@Slf4j
public class EncryptUtil {
    private static final String KEY_ALGORITHM = "AES";
    /**
     * 算法/模式/补码方式
     */
    private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";
    private static final String CODE = "utf-8";

    @Setter
    @Getter
    public static String encryptKey;

    public static String encrypt(String content) {
        return encrypt(content, encryptKey);
    }

    /**
     * 加密
     *
     * @param content
     * @param key
     * @return
     * @throws Exception
     */
    public static String encrypt(String content, String key) {
        try {
            byte[] encrypted = encrypt2bytes(content, key);
            return Base64Utils.encodeToString(encrypted);
        } catch (Exception e) {
            log.error("failed to encrypt: {} of {}", content, e);
            return null;
        }
    }

    public static byte[] encrypt2bytes(String content, String key) {
        try {
            byte[] raw = key.getBytes(CODE);
            SecretKeySpec secretKeySpec = new SecretKeySpec(raw, KEY_ALGORITHM);
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
            return cipher.doFinal(content.getBytes(CODE));
        } catch (Exception e) {
            log.error("failed to encrypt: {} of {}", content, e);
            return null;
        }
    }

    public static String decrypt(String content) {
        try {
            return decrypt(content, encryptKey);
        } catch (Exception e) {
            log.error("failed to decrypt: {}, e: {}", content, e);
            return null;
        }
    }

    /**
     * 解密
     *
     * @param content
     * @param key
     * @return
     * @throws Exception
     */
    public static String decrypt(String content, String key) throws Exception {
        return decrypt(Base64Utils.decodeFromString(content), key);
    }

    public static String decrypt(byte[] content, String key) throws Exception {
        if (key == null) {
            log.error("AES key should not be null");
            return null;
        }

        byte[] raw = key.getBytes(CODE);
        SecretKeySpec keySpec = new SecretKeySpec(raw, KEY_ALGORITHM);
        Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, keySpec);
        try {
            byte[] original = cipher.doFinal(content);
            return new String(original, CqODE);
        } catch (Exception e) {
            log.error("failed to decrypt content: {}/ key: {}, e: {}", content, key, e);
            return null;
        }
    }
}

请注意上面的实现，提供了两种方式

一个是AES加密之后使用base64编码输出，对应的是解密base64编码的数据
一个是AES加密之后，直接返回字节数组；也是直接解码字节数组

2. 测试case

我们提供了两个加密的文件，用于解密使用；

base64加解密

@Test
public void testEncrypt() throws Exception {
    String abc = "Hello, 一灰灰Blog!";
    String key = "JC66fRd3wj85k8Hr";
    String out = EncryptUtil.encrypt(abc, key);
    System.out.println(out);

    System.out.println(EncryptUtil.decrypt(out, key));
}

输出结果如:

TKrN7VKrqsAQ4JqygeHOlG21Sd3IRJ3Y11k4kOdOG4s=
Hello, 一灰灰Blog!

字节数组加解密

@Test
public void testEncryptByte() throws Exception {
    String abc = "Hello, 一灰灰Blog!";
    String key = "JC66fRd3wj85k8Hr";
    byte[] out = EncryptUtil.encrypt2bytes(abc, key);
    System.out.println(new String(out));

    System.out.println(EncryptUtil.decrypt(out, key));
}

输出结果如:

// 加密的字节数组，就是乱码... 你没看错
L???R????????Δm?I??D???Y8??N?
Hello, 一灰灰Blog!

为什么有上面两种区别？

如果我们将加密后的字节数组，直接 new String() 获得一个字符串，然后解密这个字符串，会发现解密失败哦

简单修改一下上面的测试用例

@Test
public void testEncryptByte() throws Exception {
    String abc = "Hello, 一灰灰Blog!";
    String key = "JC66fRd3wj85k8Hr";
    byte[] out = EncryptUtil.encrypt2bytes(abc, key);
    String enc = new String(out, "utf-8");
    System.out.println(enc);

    System.out.println(EncryptUtil.decrypt(enc.getBytes("utf-8"), key));
}

执行之后，发现解密失败

技术图片

为啥会出现这样情况呢？

enc = new String(out, "utf-8") 与 enc.getBytes("utf-8") 字节数组转字符串；字符串转字节数组这两个过程会导致最终生成的字节数组，与原始的不一致!!!

解密远程资源的case

最后给一个解密远程加密的二进制文件的实例case

private void binKey(String uri, String key) throws Exception {
    // 这个文件是没有base64编码，直接上传的二进制
    URL url = new URL(uri);
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    InputStream stream = connection.getInputStream();
    int lenth = connection.getContentLength();
    byte[] out = new byte[lenth];
    stream.read(out);
    stream.close();
    String ans = decrypt(out, key);
    System.out.println(ans);
}

public void testDe() throws Exception {
    String key = "5JRHMJn8xHnMDRXa";
    binKey("http://q8rnsprw0.bkt.clouddn.com/mwzz/b0001", key);
}