【题意要求】利用Java中的分组加密的相关的类包完成对输入字符串的操作。
(1)
利用java中的KeyGenerator类创建对称秘钥,利用工厂类KeyGenerator的静态方法getInstance()获得KeyGenerator()类对象;
(2)
方法getInstance()的参数为字符串类型,指定加密算法的名称如:Blowfish、DES、DESede、HmacMD5或HmacSHA1等,本题使用DES这个参数;
(3)
利用工厂类Cipher的对象可以创建密码器。同样的,getInstance()的参数为字符串类型,指定加密算法的名称,本题指定为“DES”。
其中public static byte[]
getEncCode(byte[] byteS, Key
key)方法,用来处理给出的字节数组在利用key密钥参数的基础上进行加密;而public
static byte[]
getDesCode(byte[] byteD , Key
key)方法,用来处理已经加密的字符串,利用同样的密钥进行解密。
package Practice2;
import java.io.UnsupportedEncodingException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.util.Scanner;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
public class DESForString {
public static void main(String[] args) throws
NoSuchAlgorithmException, UnsupportedEncodingException{
selectProcess();
}
public static void
selectProcess() throws NoSuchAlgorithmException,
UnsupportedEncodingException{
KeyGenerator kg =
KeyGenerator.getInstance("DES");
kg.init(56);//DES needs 56
bytes.
// 生成秘密密钥
final SecretKey secretKey =
kg.generateKey();
// byte[] key =
secretKey.getEncoded();
System.out.println("What you
are operating is the algorithm named DES to encrypt the
string.");
System.out.println(secretKey);
Scanner scanin = new
Scanner(System.in);
System.out.print("Please input
the string that you want to encrypt:\t");
String source =
scanin.nextLine();
byte[] encode =
getEncCode(source.getBytes(), secretKey);
System.out.println(encode);
System.out.print("Get the
string that you have decrypt:\t");
byte[] decode =
getDesCode(encode, secretKey);
System.out.println(new
String(decode, "gb2312"));//可处理汉字的加解密
}
public static byte[]
getEncCode(byte[] byteS, Key key) {
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;
}
public static byte[]
getDesCode(byte[] byteD , Key key) {
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;
}
}