Java加密技术 之 DES

DES
DES-Data Encryption Standard,即数据加密算法。是IBM公司于1975年研究成功并公开发表的。DES算法的入口参数有三个:Key、Data、Mode。其中Key为8个字节共64位,是DES算法的工作密钥;Data也为8个字节64位,是要被加密或被解密的数据;Mode为DES的工作方式,有两种:加密或解密。
DES算法把64位的明文输入块变为64位的密文输出块,它所使用的密钥也是64位。

通过java代码实现如下:
Java代码

import java.security.Key; 
import java.security.SecureRandom; 
 
import javax.crypto.Cipher; 
import javax.crypto.KeyGenerator; 
import javax.crypto.SecretKey; 
import javax.crypto.SecretKeyFactory; 
import javax.crypto.spec.DESKeySpec; 
 
 
/** 
 * DES安全编码组件 
 * 
 * <pre> 
 * 支持 DES、DESede(TripleDES,就是3DES)、AES、Blowfish、RC2、RC4(ARCFOUR) 
 * DES key size must be equal to 56 
 * DESede(TripleDES) key size must be equal to 112 or 168 
 * AES key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available 
 * Blowfish key size must be multiple of 8, and can only range from 32 to 448 (inclusive) 
 * RC2 key size must be between 40 and 1024 bits 
 * RC4(ARCFOUR) key size must be between 40 and 1024 bits 
 * 具体内容 需要关注 JDK Document http://.../docs/technotes/guides/security/SunProviders.html 
 * </pre> 
 */ 
public abstract class DESCoder extends Coder { 
 /** 
 * ALGORITHM 算法 <br> 
 * 可替换为以下任意一种算法,同时key值的size相应改变。 
 * 
 * <pre> 
 * DES key size must be equal to 56 
 * DESede(TripleDES) key size must be equal to 112 or 168 
 * AES key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available 
 * Blowfish key size must be multiple of 8, and can only range from 32 to 448 (inclusive) 
 * RC2 key size must be between 40 and 1024 bits 
 * RC4(ARCFOUR) key size must be between 40 and 1024 bits 
 * </pre> 
 * 
 * 在Key toKey(byte[] key)方法中使用下述代码 
 * <code>SecretKey secretKey = new SecretKeySpec(key, ALGORITHM);</code> 替换 
 * <code> 
 * DESKeySpec dks = new DESKeySpec(key); 
 * SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM); 
 * SecretKey secretKey = keyFactory.generateSecret(dks); 
 * </code> 
 */ 
 public static final String ALGORITHM = "DES"; 
 
 /** 
 * 转换密钥<br> 
 * 
 * @param key 
 * @return 
 * @throws Exception 
 */ 
 private static Key toKey(byte[] key) throws Exception { 
 DESKeySpec dks = new DESKeySpec(key); 
 SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM); 
 SecretKey secretKey = keyFactory.generateSecret(dks); 
 
 // 当使用其他对称加密算法时,如AES、Blowfish等算法时,用下述代码替换上述三行代码 
 // SecretKey secretKey = new SecretKeySpec(key, ALGORITHM); 
 
 return secretKey; 
 } 
 
 /** 
 * 解密 
 * 
 * @param data 
 * @param key 
 * @return 
 * @throws Exception 
 */ 
 public static byte[] decrypt(byte[] data, String key) throws Exception { 
 Key k = toKey(decryptBASE64(key)); 
 
 Cipher cipher = Cipher.getInstance(ALGORITHM); 
 cipher.init(Cipher.DECRYPT_MODE, k); 
 
 return cipher.doFinal(data); 
 } 
 
 /** 
 * 加密 
 * 
 * @param data 
 * @param key 
 * @return 
 * @throws Exception 
 */ 
 public static byte[] encrypt(byte[] data, String key) throws Exception { 
 Key k = toKey(decryptBASE64(key)); 
 Cipher cipher = Cipher.getInstance(ALGORITHM); 
 cipher.init(Cipher.ENCRYPT_MODE, k); 
 
 return cipher.doFinal(data); 
 } 
 
 /** 
 * 生成密钥 
 * 
 * @return 
 * @throws Exception 
 */ 
 public static String initKey() throws Exception { 
 return initKey(null); 
 } 
 
 /** 
 * 生成密钥 
 * 
 * @param seed 
 * @return 
 * @throws Exception 
 */ 
 public static String initKey(String seed) throws Exception { 
 SecureRandom secureRandom = null; 
 
 if (seed != null) { 
 secureRandom = new SecureRandom(decryptBASE64(seed)); 
 } else { 
 secureRandom = new SecureRandom(); 
 } 
 
 KeyGenerator kg = KeyGenerator.getInstance(ALGORITHM); 
 kg.init(secureRandom); 
 
 SecretKey secretKey = kg.generateKey(); 
 
 return encryptBASE64(secretKey.getEncoded()); 
 } 
}
延续上一个类的实现,我们通过MD5以及SHA对字符串加密生成密钥,这是比较常见的密钥生成方式。 
再给出一个测试类: 
Java代码 收藏代码
import static org.junit.Assert.*; 
 
 
import org.junit.Test; 
 
/** 
 * 
 * @author 梁栋 
 * @version 1.0 
 * @since 1.0 
 */ 
public class DESCoderTest { 
 
 @Test 
 public void test() throws Exception { 
 String inputStr = "DES"; 
 String key = DESCoder.initKey(); 
 System.err.println("原文:t" + inputStr); 
 
 System.err.println("密钥:t" + key); 
 
 byte[] inputData = inputStr.getBytes(); 
 inputData = DESCoder.encrypt(inputData, key); 
 
 System.err.println("加密后:t" + DESCoder.encryptBASE64(inputData)); 
 
 byte[] outputData = DESCoder.decrypt(inputData, key); 
 String outputStr = new String(outputData); 
 
 System.err.println("解密后:t" + outputStr); 
 
 assertEquals(inputStr, outputStr); 
 } 
}

得到的输出内容如下:
Console代码

原文: DES
密钥: f3wEtRrV6q0=
加密后: C6qe9oNIzRY=
解密后: DES

由控制台得到的输出,我们能够比对加密、解密后结果一致。这是一种简单的加密解密方式,只有一个密钥。
其实DES有很多同胞兄弟,如DESede(TripleDES)、AES、Blowfish、RC2、RC4(ARCFOUR)。这里就不过多阐述了,大同小异,只要换掉ALGORITHM换成对应的值,同时做一个代码替换SecretKey secretKey = new SecretKeySpec(key, ALGORITHM);就可以了,此外就是密钥长度不同了。

Java代码

/** 
 * DES key size must be equal to 56 
 * DESede(TripleDES) key size must be equal to 112 or 168 
 * AES key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available 
 * Blowfish key size must be multiple of 8, and can only range from 32 to 448 (inclusive) 
 * RC2 key size must be between 40 and 1024 bits 
 * RC4(ARCFOUR) key size must be between 40 and 1024 bits
<span class="comment">**/</span>
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