Base加密解密、DES/AES对称加密

Cita 2020-07-24

1. Base64工具类

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;

/**
 * Base64加密解密工具类
 */
public class Base64 {
    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();

    public static String encode(byte[] data) {
        int start = 0;
        int len = data.length;
        StringBuffer buf = new StringBuffer(data.length * 3 / 2);
        int end = len - 3;
        int i = start;
        int n = 0;

        while (i <= end) {
            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff);
            
            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append(legalChars[d & 63]);
            i += 3;
            if (n++ >= 14) {
                n = 0;
                buf.append(" ");
            }
        }
        if (i == start + len - 2) {
            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8);
            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append("=");
        } else if (i == start + len - 1) {
            int d = (((int) data[i]) & 0x0ff) << 16;
            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append("==");
        }
        return buf.toString();
    }

    private static int decode(char c) {
        if (c >= 'A' && c <= 'Z')
            return ((int) c) - 65;
        else if (c >= 'a' && c <= 'z')
            return ((int) c) - 97 + 26;
        else if (c >= '0' && c <= '9')
            return ((int) c) - 48 + 26 + 26;
        else
            switch (c) {
                case '+':
                    return 62;
                case '/':
                    return 63;
                case '=':
                    return 0;
                default:
                    throw new RuntimeException("unexpected code: " + c);
            }
    }

    /**
     * @Description: 将给定的Base64编码字符串解码为新的字节数组,返回保存解码数据的字节数组。
     */
    public static byte[] decode(String s) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            decode(s, bos);
        } catch (IOException e) {
            throw new RuntimeException();
        }
        byte[] decodedBytes = bos.toByteArray();
        try {
            bos.close();
            bos = null;
        } catch (IOException ex) {
            System.err.println("Error while decoding BASE64: " + ex.toString());
        }
        return decodedBytes;
    }

    private static void decode(String s, OutputStream os) throws IOException {
        int i = 0;
        int len = s.length();

        while (true) {
            while (i < len && s.charAt(i) <= ' ')
                i++;
            if (i == len)
                break;
            int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6) + (decode(s.charAt(i + 3)));
            os.write((tri >> 16) & 255);
            if (s.charAt(i + 2) == '=')
                break;
            os.write((tri >> 8) & 255);
            if (s.charAt(i + 3) == '=')
                break;
            os.write(tri & 255);
            i += 4;
        }
    }

    public static void main(String[] args) throws UnsupportedEncodingException {
        String content = "hello Base64";
        System.out.println("加密之前：" + content);

        // 加密
        String jiami = Base64.encode(content.getBytes("utf-8"));
        System.out.println("加密后的内容：" + jiami);

        // 解密
        String jiemi = new String(Base64.decode(jiami));
        System.out.println("解密后的内容：" + jiemi);
    }
}

2. DES数据加密标准（Data Encryption Standard）对称加密

概述：加密和解密都使用同一把**，这种加密方法称为对称加密，也称为单**加密。简单理解为：加密和解密都是同一把钥匙。

简介：DES算法**总长度64位，加密56位+8位(即每个第8位都用作奇偶校验)，作为校验码， 不参与加密运算。

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

/**
 * @detail DES对称加密 
 * @author Cita
 */
public class DES {
	
	public static void main(String[] args) throws Exception {
		/**
		 * 1. 明文
		 * 2. 提供原始**： 长度64位,8个字节（必须）
		 */
		String text = "hello DES";
		String originKey = "a2c4e6g8";
        
		// 加密
		String cryptText = desEncript(text,originKey);
		System.out.println("加密后："+cryptText);
         // 解密
		String decipherText = descript(cryptText,originKey);
		System.out.println("解密后："+decipherText);
	}
	
	// 加密方式
	public static final String MODE = "DES";
	
	/**
	 * @Description: （加密）Cipher的DES算法
	 * @throws: NoSuchAlgorithmException: 填充异常(工作模式和填充模式)
	 * @throws：NoSuchPaddingException: 没有此算法异常
	 * @throws: InvalidKeyException: 无效的**异常
	 * @throws: IllegalBlockSizeException: 非法块大小异常
	 */
	private static String desEncript(String text,String originKey) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
		//1.获取加密算法工具类
		Cipher cipher = Cipher.getInstance(MODE);
		
		/** 
		 * 2.对工具类对象进行初始化
		 * opmode: 加密/解密模式Cipher.ENCRYPT_MODE加密
		 * key: 对原始**处理之后的**
		 */
		SecretKeySpec key = new SecretKeySpec(originKey.getBytes(),MODE);
		cipher.init(Cipher.ENCRYPT_MODE, key);
		
		//3.用加密工具类对象对明文加密
		byte[] doFinal = cipher.doFinal(text.getBytes());
		
		//4.Base64.encode(doFinal);base64防止出现乱码
		return Base64.encode(doFinal);
	}
	
	/**
	 * @Description DES 解密
	 */
	public static String descript(String text,String originKey)throws Exception {
		//1.获取加密算法工具类
		Cipher cipher = Cipher.getInstance(MODE);
		
		//2.对工具类对象进行初始化Cipher.DECRYPT_MODE解密
		Key key = new SecretKeySpec(originKey.getBytes(),MODE);
		cipher.init(Cipher.DECRYPT_MODE, key);
		
		//3.使用了base64防止乱码,要先base64解码
		byte[] decode = Base64.decode(text);
		
		//4.用加密工具类对象对解密
		byte[] doFinal = cipher.doFinal(decode);
		
		return new String(doFinal);
	}
}

3. AES高级加密标准（ Advanced Encryption Standard）对称加密

​ 由于现在电脑的多线程解密时间更短出现了AES，是在DES的基础上把**提升到了16位进行加密。

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

/**
 * @detail AES对称加密 
 * @author Cita
 */
public class AES {
	
	public static void main(String[] args) throws Exception {
		/**
		 * 1. 明文
		 * 2. 提供原始**： 长度128位,16个字节（必须）
		 */
		String text = "hello AES";
		String originKey = "a2c4e6g8i9k0mlno";
        
		// 加密
		String cryptText = desEncript(text,originKey);
		System.out.println("加密后："+cryptText);
         // 解密
		String decipherText = descript(cryptText,originKey);
		System.out.println("解密后："+decipherText);
	}
	
	// 加密方式
	public static final String MODE = "AES";
	
	/**
	 * @Description: （加密）Cipher的AES算法
	 */
	private static String desEncript(String text,String originKey) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
		Cipher cipher = Cipher.getInstance(MODE);
		cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(originKey.getBytes(),MODE));
		return Base64.encode(cipher.doFinal(text.getBytes()));
	}
	
	/**
	 * @Description AES 解密
	 */
	public static String descript(String text,String originKey)throws Exception {
		Cipher cipher = Cipher.getInstance(MODE);
		cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(originKey.getBytes(),MODE));
		return new String(cipher.doFinal(Base64.decode(text)));	
	}	
}