学步园

package com.app.nf_9501.util;

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

public class DesUtil {
	
	/**
	  * 将字符串转化为UTF8格式进行DES编码，不足8个字节在API内部自动补齐
	  * 
	  * @param encryptString 要进行加密的字符串
	  * @param encryptKey 字符串加密KEY
	  * @return 加密完成的字符串
	  * @throws cipher.doFina解析异常 
	  */
	 public static String encryptDES(String encryptString, String encryptKey)throws Exception {
		
		 if (encryptString.trim().equals("")) {
			return encryptString;
		}

		byte[] iv = encryptKey.getBytes();
		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());

		String str = bytesToHexString(encryptedData);

		return str;
	 }
	 
	 public static String decryptDES(String decryptString, String encryptKey)throws Exception {
		
		 if (decryptString.trim().equals("")) {
			return decryptString;
		}

		byte[] iv = encryptKey.getBytes();
		IvParameterSpec zeroIv = new IvParameterSpec(iv);
		SecretKeySpec key = new SecretKeySpec(encryptKey.getBytes(), "DES");
		Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
		cipher.init(Cipher.DECRYPT_MODE, key, zeroIv);
		byte[] encryptedData = hexStringToBytes(decryptString);

		String str = new String(cipher.doFinal(encryptedData));

		return str;
	}
	 

	/**
	 * Convert byte[] to hex string.
	 * 
	 * @param src byte[] data
	 * 
	 * @return hex string
	 */
	private static String bytesToHexString(byte[] src) {
		StringBuilder stringBuilder = new StringBuilder("");
		if (src == null || src.length <= 0) {
			return null;
		}
		for (int i = 0; i < src.length; i++) {
			int v = src[i] & 0xFF;
			String hv = Integer.toHexString(v);
			if (hv.length() < 2) {
				stringBuilder.append(0);
			}
			stringBuilder.append(hv);
		}
		return stringBuilder.toString();
	}

	/**
	 * Convert hex string to byte[]
	 * 
	 * @param hexString
	 *            the hex string
	 * @return byte[]
	 */
	private static byte[] hexStringToBytes(String hexString) {
		if (hexString == null || hexString.equals("")) {
			return null;
		}
		hexString = hexString.toUpperCase();
		int length = hexString.length() / 2;
		char[] hexChars = hexString.toCharArray();
		byte[] d = new byte[length];
		for (int i = 0; i < length; i++) {
			int pos = i * 2;
			d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
		}
		return d;
	}

	/**
	 * Convert char to byte
	 * 
	 * @param c
	 *            char
	 * @return byte
	 */
	private static byte charToByte(char c) {
		return (byte) "0123456789ABCDEF".indexOf(c);
	}
}