Java加密算法DES

密鑰加密也稱為對稱加密，速度快，但加密和解密的鑰匙必須相同，只有通信雙方才能知道鑰匙。

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;

import javax.crypto.spec.IvParameterSpec;
/**

DES 算法       1972美國IBM研制，對稱加密算法 
@author stone 
@date 2014-03-10 04:47:05 
*/

public class DES {

 // 算法名稱

 public static final String KEY_ALGORITHM = "DES";

 // 算法名稱/加密模式/填充方式

 public static final String CIPHER_ALGORITHM_ECB = "DES/ECB/PKCS5Padding";

 public static final String CIPHER_ALGORITHM_CBC = "DES/CBC/PKCS5Padding";
public static void main(String[] args) throws Exception {

 /* 
  * 使用 ECB mode 
  * 密鑰生成器 生成密鑰 
  * ECB mode cannot use IV 
  */  
 byte[] key = generateKey();   
 byte[] encrypt = encrypt("胃炎F#*（x）".getBytes(), key);  
 System.out.println(new String(decrypt(encrypt, key)));  



    /* 
     * 使用CBC mode 
     * 使用密鑰工廠生成密鑰，加密 解密 
     * iv: DES in CBC mode and RSA ciphers with OAEP encoding operation. 
     */  
    DESKeySpec dks = new DESKeySpec(generateKey());  
    SecretKeyFactory factory = SecretKeyFactory.getInstance(KEY_ALGORITHM);  
    SecretKey secretKey = factory.generateSecret(dks);  
    Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_CBC);  
    cipher.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(getIV()));  
    byte[] enc = cipher.doFinal("胃炎A%F#*（x）".getBytes()); //加密  

    cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(getIV()));  
    byte[] dec = cipher.doFinal(enc); // 解密  
    System.out.println(new String(dec));  
}  

static byte[] getIV() {  
    String iv = "asdfivh7"; //IV length: must be 8 bytes long  
    return iv.getBytes();  
}  

/** 
 * 生成密鑰 
 *  
 * @return 
 * @throws Exception 
 */  
private static byte[] generateKey() throws Exception {  
    KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_ALGORITHM);  
    keyGenerator.init(56); //des 必須是56, 此初始方法不必須調用  
    SecretKey secretKey = keyGenerator.generateKey();  
    return secretKey.getEncoded();  
}  

/** 
 * 還原密鑰 
 *  
 * @param key 
 * @return 
 * @throws Exception  
 */  
private static Key toKey(byte[] key) throws Exception {  
    DESKeySpec des = new DESKeySpec(key);  
    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(KEY_ALGORITHM);  
    SecretKey secretKey = keyFactory.generateSecret(des);  
    return secretKey;  
}  

/** 
 * 加密  
 * @param data 原文 
 * @param key 
 * @return 密文 
 * @throws Exception 
 */  
public static byte[] encrypt(byte[] data, byte[] key) throws Exception {  
    Key k = toKey(key);  
    Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_ECB);  
    cipher.init(Cipher.ENCRYPT_MODE, k, new SecureRandom());  
    return cipher.doFinal(data);  
}  
/** 
 * 解密 
 * @param data 密文 
 * @param key 
 * @return 明文、原文 
 * @throws Exception 
 */  
public static byte[] decrypt(byte[] data, byte[] key) throws Exception {  
    Key k = toKey(key);  
    Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_ECB);  
    cipher.init(Cipher.DECRYPT_MODE, k, new SecureRandom());  
    return cipher.doFinal(data);  
}  

}  </pre>