DES 数据加密

于 2016-07-19 11:01:53 发布
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CC 4.0 BY-SA版权
分类专栏： 功能 文章标签： 加密 DES 加密数据
版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。
本文链接：https://blog.youkuaiyun.com/cuiweicai/article/details/51953973
本文介绍了使用DES算法进行加密和解密的具体实现方法，包括8位密钥和大于8位密钥的情况，并提供了完整的Java代码示例。

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在开发的时候向服务发起请求的时候，有时候请求的结果需要加密。
本文简单介绍下DES的加密用法；

一，八位的密钥的加解密

    String plaintext = "我1234567890从";
    String ciphertext = DES.encryptDES(plaintext, "89018D39");

            Log.d("DES","明文：" + plaintext);
            Log.d("DES","密钥：" + "89018D39");
            Log.d("DES","密文：" + ciphertext);
            Log.d("DES","解密后：" + DES.decryptDES(ciphertext, "89018D39"));

日志：

 D/DES: 明文：我1234567890从
 D/DES: 密钥：89018D39
 D/DES: 密文：Tpv9Fxx36WElIZN1QdCZpa3NGbzSpyNi
 D/DES: 解密后：我1234567890从

涉及的两个类：

Base64 类

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

/**
 * Created by jimda on 2016/7/14.
 */
public class Base64 {
    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
            .toCharArray();

    /**
     * data[]进行编码
     *
     * @param data
     * @return
     */
    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();
    }


    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;
        }
    }
    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);
            }
    }

}

DES类

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * Created by jimda on 2016/7/14.
 */
public class DES {
    private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 };

    public static String encryptDES(String encryptString, String encryptKey)
            throws Exception {
        IvParameterSpec zeroIv = new IvParameterSpec(iv);
        SecretKeySpec key = new SecretKeySpec(encryptKey.getBytes(), "DES");
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv);
        byte[] encryptedData = cipher.doFinal(encryptString.getBytes());
        return Base64.encode(encryptedData);
    }


    public static String decryptDES(String decryptString, String decryptKey)
            throws Exception {
        byte[] byteMi = Base64.decode(decryptString);
        IvParameterSpec zeroIv = new IvParameterSpec(iv);
        SecretKeySpec key = new SecretKeySpec(decryptKey.getBytes(), "DES");
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, key, zeroIv);
        byte decryptedData[] = cipher.doFinal(byteMi);

        return new String(decryptedData);
    }
}

二，密钥大于8位的DES加解密

   String plaintext = "我1234567890从";
   String ciphertext = Des2.encode("eb3e52920ffcd2b676cb17c3528e974a",plaintext);
             Log.d("DES","密钥：" + "eb3e52920ffcd2b676cb17c3528e974a");
             Log.d("DES","解密后：" + Des2.decodeValue( "eb3e52920ffcd2b676cb17c3528e974a", ciphertext));

Log

 密钥：eb3e52920ffcd2b676cb17c3528e974a
 解密后：我1234567890从

涉及的类
Des2

import java.security.Key;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;


public class Des2
{
    public static final String ALGORITHM_DES = "DES/CBC/PKCS5Padding";
    private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 };
    /**
     * DES算法，加密
     *
     * @param data 待加密字符串
     * @param key  加密私钥，长度不能够小于8位
     * @return 加密后的字节数组，一般结合Base64编码使用
     * @throws CryptException 异常
     */
    public static String encode(String key,String data) throws Exception
    {
        return encode(key, data.getBytes());
    }
    /**
     * DES算法，加密
     *
     * @param data 待加密字符串
     * @param key  加密私钥，长度不能够小于8位
     * @return 加密后的字节数组，一般结合Base64编码使用
     * @throws CryptException 异常
     */
    public static String encode(String key,byte[] data) throws Exception
    {
        try
        {
            DESKeySpec dks = new DESKeySpec(key.getBytes());

            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            //key的长度不能够小于8位字节
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
        //    IvParameterSpec iv = new IvParameterSpec("********".getBytes());
            IvParameterSpec zeroIv = new IvParameterSpec(iv);
            AlgorithmParameterSpec paramSpec = zeroIv;
            cipher.init(Cipher.ENCRYPT_MODE, secretKey,paramSpec);

            byte[] bytes = cipher.doFinal(data);
            return Base64.encode(bytes);
        } catch (Exception e)
        {
            throw new Exception(e);
        }
    }
    /**
     * DES算法，解密
     *
     * @param data 待解密字符串
     * @param key  解密私钥，长度不能够小于8位
     * @return 解密后的字节数组
     * @throws Exception 异常
     */
    public static byte[] decode(String key,byte[] data) throws Exception
    {
        try
        {
            SecureRandom sr = new SecureRandom();
            DESKeySpec dks = new DESKeySpec(key.getBytes());
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            //key的长度不能够小于8位字节
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
        //    IvParameterSpec iv = new IvParameterSpec("********".getBytes());
            IvParameterSpec zeroIv = new IvParameterSpec(iv);
            AlgorithmParameterSpec paramSpec = zeroIv;
            cipher.init(Cipher.DECRYPT_MODE, secretKey,paramSpec);
            return cipher.doFinal(data);
        } catch (Exception e)
        {
//         e.printStackTrace();
            throw new Exception(e);
        }
    }

    /**
     * 获取编码后的值
     * @param key
     * @param data
     * @return
     * @throws Exception
     * @throws Exception
     */
    public static String decodeValue(String key,String data) throws Exception
    {
        byte[] datas;
        String value = null;

        datas = decode(key, Base64.decode(data));

        value = new String(datas);
        if (value.equals("")){
            throw new Exception();
        }
        return value;
    }
}
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