对称加密算法

阅读更多

参考：http://snowolf.iteye.com/blog/380034

 

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：Coder类见 单向加密算法

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
 *
 *
 * 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
 *
 *
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
 public abstract class DESCoder extends Coder {
     /**
     * ALGORITHM 算法
     * 可替换为以下任意一种算法，同时key值的size相应改变。
     *
     *
     * 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
     *
     *
     * 在Key toKey(byte[] key)方法中使用下述代码
     * SecretKey secretKey = new SecretKeySpec(key, ALGORITHM); 替换
     *
     *
     */
     public static final String ALGORITHM = "DES";

     /**
     * 转换密钥
     *
     * @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());
    }
}

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
 * 
 * 
 * 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
 * 
 * 
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
public abstract class DESCoder extends Coder {
	/**
	 * ALGORITHM 算法 

	 * 可替换为以下任意一种算法，同时key值的size相应改变。
	 * 
	 * 
	 * 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
	 * 
	 * 
	 * 在Key toKey(byte[] key)方法中使用下述代码
	 * SecretKey secretKey = new SecretKeySpec(key, ALGORITHM); 替换
	 * 
	 * DESKeySpec dks = new DESKeySpec(key);
	 * SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
	 * SecretKey secretKey = keyFactory.generateSecret(dks);
	 * 
	 */
	public static final String ALGORITHM = "DES";

	/**
	 * 转换密钥

	 * 
	 * @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：

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);
    }
}

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：

原文: DES
密钥: f3wEtRrV6q0=

加密后:    C6qe9oNIzRY=

解密后:    DES

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。

/**
 * 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
 **/