des加密工具类（des加密算法详解）

  des算法简介

des 算法

  des算法为密码体制中的对称密码体制，又被称为美国数据加密标准，是1972年美国ibm公司研制的对称密码体制加密算法。明文按64位进行分组，密钥长64位，密钥事实上是56位参与des运算（第8、16、24、32、40、48、56、64位是校验位，使得每个密钥都有奇数个1）分组后的明文组和56位的密钥按位替代或交换的方法形成密文组的加密方法。

  des算法具有极高安全性，除了用穷举搜索法对des算法进行攻击外，还没有发现更有效的办法。而56位长的密钥的穷举空间为2^56，这意味着如果一台计算机的速度是每一秒钟检测一百万个密钥，则它搜索完全部密钥就需要将近2285年的时间，可见，这是难以实现的。然而，这并不等于说des是不可破解的。而实际上，随着硬件技术和internet的发展，其破解的可能性越来越大，而且，所需要的时间越来越少。使用经过特殊设计的硬件并行处理要几个小时。

  为了克服des密钥空间小的缺陷，人们又提出了三重des的变形方式。

  maven 依赖

  工具类对于加密后使用ba64进行编码，所以需要依赖apache commons codec。

<dependency>    <groupid>commons-codec</groupid>    <artifactid>commons-codec</artifactid>    <version>1.9</version></dependency><dependency>    <groupid>log4j</groupid>    <artifactid>log4j</artifactid>    <version>1.2.17</version></dependency>

  工具类实现

  desutil提供了针对文本内容、字节数组内容的加解密实现，desutil工具类可以直接复制使用，代码如下：

package com.arhorchin.curitit.enordecryption.des;import java.curity.key;import j将进酒背景avax.crypto.cipher;import javax.crypto.cretkeyfactory;import javax.crypto.spec.deskeyspec;import javax.crypto.spec.ivparameterspec;import org.apache.commons.codec.binary.ba64;import org.apache.log4j.logger;/** * @author curitit. * @note des加密算法实现. */public class desutil {    /**     * logger.     */    private static logger logger = logger.getlogger(desutil.class);    /**     * 数据编码.     */    private static final string chart_utf8 = "utf-8";    /**     * 算法编号.     */    public static final string des_name = "des";    /**     * cbc模式串.     */    public static final string des_name_ecb = "des/cbc/pkcs5padding";    /**     * 初始向量.     */    public static final byte[] des_key_iv = { 1, 2, 3, 4, 5, 6, 7, 8 };    /**     * 根据密码生成key.要求：密码长度是8的倍数.     * @param deskeypwd 密码字符串.     * @return des密钥.     * @throws exception 可能异常.     */    public static string generatedeskey(string deskeypwd) throws exception {        deskeyspec deskeyspec = null;        cretkeyfactory keyfactory = null;        byte[] keybytes = null;        deskeyspec = new deskeyspec(deskeypwd.getbytes(chart_utf8));        keyfactory = cretkeyfactory.getinstance(des_name);        keybytes = keyfactory.generatecret(deskeyspec).getencoded();        return ba64.encodeba64string(keybytes);   2035年的我 }    /**     * 对文本内容进行加密.     * @param plaintext 待加密明文内容.     * @param deskey des密钥.     * @return 加密的密文.     */    public static string encodetext(string plaintext, string deskey) throws exception {        byte[] deskeybytes = null;        byte[] plainbytes = null;        byte[] cipherbytes = null;        try {            deskeybytes = ba64.decodeba64(deskey);            plainbytes = plaintext.getbytes(chart_utf8);            cipherbytes = encodebycbc(plainbytes, deskeybytes, des_key_iv);            return ba64.encodeba64string(cipherbytes);        } catch (exception ex) {            logger.error("desutil.encodetext.", ex);            return "";        }    }    /**     * 对文本密文进行解密.     * @param ciphertext 待解密密文.     * @param deskey des密钥.     * @return 解密的明文.     */    public static string decodetext(string ciphertext, string deskey) throws exception {        byte[] deskeybytes = null;        byte[] cipherbytes = null;        byte[] plainbytes = null;        try {            deskeybytes = ba64.decodeba64(deskey);            cipherbytes = ba64.decodeba64(ciphertext);            plainbytes = decodebycbc(cipherbytes, deskeybytes, des_key_iv);            return new string(plainbytes, chart_utf8);        } catch (exception ex) {            logger.error("desutil.decodetext.", ex);            return "";        }    }    /**     * 对字节数组内容进行加密.     * @param plaintext 待加密明文内容.     * @param dkey des密钥.     * @return 加密的密文.     */    public static byte[] encodebytes(byte[] plainbytes, string deskey) throws exception {        byte[] deskeybytes = null;        byte[] cipherbytes = null;        try {            deskeybytes = ba64.decodeba64(deskey);            cipherbytes = encodebycbc(plainbytes, deskeybytes, des_key_iv);            return cipherbytes;        } catch (exception ex) {            logger.error("desutil.encodebytes.", ex);            return new byte[0];        }    }    /**     * 对字节数组密文进行解密.     * @param ciphertext 待解密密文.     * @param deskey des密钥.     * @return 解密的明文.     */    public static byte[] decodebytes(byte[] cipherbytes, string deskey) throws exception {        byte[] deskeybytes = null;        byte[] plainbytes = null;        try {            deskeybytes = ba64.decodeba64(deskey);            plainbytes = decodebycbc(cipherbytes, deskeybytes, des_key_iv);            return plainbytes;        } catch (exception ex) {            logger.error("desutil.decodebytes.", ex);            return new byte[0];        }    }    /**     * des算法使用cbc模式进行加密.     * @param plainbytes 原文内容.     * @param deskey des密钥.     * @param keyiv des初始向量.     * @return 加密后的内容.     * @throws exception .     */    public static byte[] encodebycbc(byte[] plainbytes, byte[] deskey, byte[] keyiv) throws exception {        key deskey = null;        deskeyspec desspec = null;        cretkeyfactory keyfactory = null;        cipher cipher = null;        ivparameterspec ivspec = null;        byte[] cipherout = null;        desspec = new deskeyspec(deskey);        keyfactory = cretkeyfactory.getinstance(des_name);        deskey = keyfactory.generatecret(desspec);        cipher = cipher.getinstance(des_name_ecb);        ivspec = new ivparameterspec(keyiv);        cipher.init(cipher.encrypt_mode, deskey, ivspec);        cipherout = cipher.dofinal(plainbytes);        return cipherout;    }    /**     * des算法使用cbc模式进行解密.     * @param plainbytes 密文内容.     * @param deskey des密钥.     * @param keyiv des初始向量.     * @欧洲杯大名单return 解密后的内容.     * @throws exception .     */    public static byte[] decodebycbc(byte[] plainbytes, byte[] deskey, byte[] keyiv) throws exception {        key deskey = null;        deskeyspec desspec = null;        cretkeyfactory keyfactory = null;        cipher cipher = null;        ivparameterspec ivspec = null;        byte[] cipherout = null;        desspec = new deskeyspec(deskey);        keyfactory = cretkeyfactory.getinstance(des阁楼装修效果图_name);        deskey = keyfactory.generatecret(desspec);        cipher = cipher.getinstance(des_name_ecb);        ivspec = new ivparameterspec(keyiv);        cipher.init(cipher.decrypt_mode, deskey, ivspec);        cipherout = cipher.dofinal(plainbytes);        return cipherout;    }}

  工具类测试

package com.arhorchin.curitit.enordecryption.des;import java.util.arrays;/** * @author curitit. * @note desutil测试类. */public class desutiltester {    妈妈的爱全本阅读public static void main(string[] args) throws exception {        string deskeypwd = "1234567887654321";        string deskey = null;        string plaintext = "this is 一段明文内容！";        string ciphertext = null;        system.out.println("----------------------- 获取des秘钥 -------------------------");        deskey = desutil.generatedeskey(deskeypwd);        system.out.println("秘钥：" + deskey);        system.out.println();        // 文本加解密测试.        system.out.println("----------------------- 文本加解密测试 -------------------------");        system.out.println("明文：" + plaintext);        ciphertext = desutil.encodetext(plaintext, deskey);        system.out.println("密文：" + ciphertext);        plaintext = desutil.decodetext(ciphertext, deskey);        system.out.println("解密明文：" + plaintext);        system.out.println();        system.out.println("----------------------- 字节数组加解密测试 -------------------------");        byte[] plainbytes = plaintext.getbytes("utf-8");        byte[] cipherbytes = null;        system.out.println("明文：" + arrays.tostring(plainbytes));        cipherbytes = desutil.encodebytes(plainbytes, deskey);        system.out.println("密文：" + arrays.tostring(cipherbytes));        plainbytes = desutil.decodebytes(cipherbytes, deskey);        system.out.println("解密明文：" + arrays.tostring(plainbytes));        system.out.println();    }}

  控制台输出

  查看console中的控制台内容，明文和解密后明文对比，可以确认desutil可以正常工作，控制台如下图：

----------------------- 获取des秘钥 -------------------------秘钥：mtiyndq3nzg=----------------------- 文本加解密测试 -------------------------明文：this is 一段明文内容！密文：2guhziwpad0klmjyrzerlw83acn0am0f19nz18nf214=解密明文：this is 一段明文内容！----------------------- 字节数组加解密测试 -------------------------明文：[84, 104, 105, 115, 32, 105, 115, 32, -28, -72, -128, -26, -82, -75, -26, -104, -114, -26, -106, -121, -27, -122, -123, -27, -82, -71, -17, -68, -127]密文：[-38, 11, -121, -52, -123, -87, 105, -35, 36, -108, -56, -14, 69, -111, 17, 45, 111, 55, 105, -61, 116, 0, -51, 5, -41, -45, 89, -41, -61, 69, -37, 94]解密明文：[84, 104, 105, 115, 32, 105, 115, 32, -28, -72, -128, -26, -82, -75, -26, -104, -114, -26, -106, -121, -27, -122, -123, -27, -82, -71, -17, -68, -127]

  总结

  现代密码学应用中，des的身影已越来越少见，随着硬件和互联网的发展，des在安全性方面的劣势变得尤为明显。在des之后，逐渐出现了用于过渡的3des以及新一代密码算法aes，3des是为了使得des更加难以破解，使用三次des加解密叠加得到的密码算法。而aes是作为下一代对称密码学算法，使用完全不同的算法进行了实现。在实际应用中，可以根据个人所需，选择合适的算法进行应用。