Java的DES算法实现
昨天按照网上的资料写DES,但最后在byte[]->String上卡住了.DES需要8位解密,而这种转换后,会讲btye[]补位造成长度和内容改变.很郁闷....最后又在网上找了一个已经实现的例子运行后无问题:代码如下:
package des;
import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
/**
*
* 使用DES加密与解密,可对byte[],String类型进行加密与解密 密文可使用String,byte[]存储.
*
* 方法: void getKey(String strKey)从strKey的字条生成一个Key
*
* String getEncString(String strMing)对strMing进行加密,返回String密文 String
* getDesString(String strMi)对strMin进行解密,返回String明文
*
* byte[] getEncCode(byte[] byteS)byte[]型的加密 byte[] getDesCode(byte[]
* byteD)byte[]型的解密
*/
public class DesEncrypt {
Key key;
/**
* 根据参数生成KEY
*
* @param strKey
*/
public void getKey(String strKey) {
try {
KeyGenerator _generator = KeyGenerator.getInstance("DES");
_generator.init(new SecureRandom(strKey.getBytes()));
this.key = _generator.generateKey();
_generator = null;
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 加密String明文输入,String密文输出
*
* @param strMing
* @return
*/
public String getEncString(String strMing) {
byte[] byteMi = null;
byte[] byteMing = null;
String strMi = "";
try {
return byte2hex(getEncCode(strMing.getBytes()));
// byteMing = strMing.getBytes("UTF8");
// byteMi = this.getEncCode(byteMing);
// strMi = new String( byteMi,"UTF8");
} catch (Exception e) {
e.printStackTrace();
} finally {
byteMing = null;
byteMi = null;
}
return strMi;
}
/**
* 解密 以String密文输入,String明文输出
*
* @param strMi
* @return
*/
public String getDesString(String strMi) {
byte[] byteMing = null;
byte[] byteMi = null;
String strMing = "";
try {
return new String(getDesCode(hex2byte(strMi.getBytes())));
// byteMing = this.getDesCode(byteMi);
// strMing = new String(byteMing,"UTF8");
} catch (Exception e) {
e.printStackTrace();
} finally {
byteMing = null;
byteMi = null;
}
return strMing;
}
/**
* 加密以byte[]明文输入,byte[]密文输出
*
* @param byteS
* @return
*/
private byte[] getEncCode(byte[] byteS) {
byte[] byteFina = null;
Cipher cipher;
try {
cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, key);
byteFina = cipher.doFinal(byteS);
} catch (Exception e) {
e.printStackTrace();
} finally {
cipher = null;
}
return byteFina;
}
/**
* 解密以byte[]密文输入,以byte[]明文输出
*
* @param byteD
* @return
*/
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private byte[] getDesCode(byte[] byteD) {
Cipher cipher;
byte[] byteFina = null;
try {
cipher = Cipher.getInstance("DES");
cipher.init(Cipher.DECRYPT_MODE, key);
byteFina = cipher.doFinal(byteD);
} catch (Exception e) {
e.printStackTrace();
} finally {
cipher = null;
}
return byteFina;
}
/**
* 二行制转字符串
*
* @param b
* @return
*/
public static String byte2hex(byte[] b) { // 一个字节的数，
// 转成16进制字符串
String hs = "";
String stmp = "";
for (int n = 0; n < b.length; n) {
// 整数转成十六进制表示
stmp = (java.lang.Integer.toHexString(b & 0XFF));
if (stmp.length() == 1)
hs = hs "0" stmp;
else
hs = hs stmp;
}
return hs.toUpperCase(); // 转成大写
}
public static byte[] hex2byte(byte[] b) {
if ((b.length % 2) != 0)
throw new IllegalArgumentException("长度不是偶数");
byte[] b2 = new byte;
for (int n = 0; n < b.length; n= 2) {
String item = new String(b, n, 2);
// 两位一组，表示一个字节,把这样表示的16进制字符串，还原成一个进制字节
b2 = (byte) Integer.parseInt(item, 16);
}
return b2;
}
public static void main(String[] args) {
System.out.println("hello");
DesEncrypt des = new DesEncrypt();//实例化一个对像
des.getKey("aadd");//生成密匙
String strEnc = des.getEncString("云海飞舞雲122");//加密字符串,返回String的密文
System.out.println(strEnc);
String strDes = des.getDesString(strEnc);//把String 类型的密文解密
System.out.println(strDes);
new DesEncrypt();
}
}
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