Question

JAVA简单文件加密 求JAVA源代码

1. Java 程序名为 EncryptFile.java。在命令行运行方法为
java EncryptFile input_file password output_file
2. 实现利用密码对输入文件的简单加密算法。EncryptFile 类中定义两个方
法：
2.1 Encrypt 方法将输入文件中的每个字符和密码中的对应字符做循环按位
异或操作，即将输入文件的第n 个字符和密码的第(n % length)个字符进行
按位异或，得到的结果字符逐一输出到输出文件, 其中length 为密码的长度。
2.2 main 方法首先检查命令行参数是否正确，包括命令行参数的个数，输入
文件是否已经存在，输出文件是否已经存在。如果有错误，则打印出错
信息并结束程序。如果正确，调用Encrypt 方法生成output.txt。
最后再读入output.txt 文件，并在屏幕上显示其内容。
3. 为测试程序，执行
java EncryptFile input.txt 12345678 output.txt

Answer 1

md5加密：
package com.ncs.pki.util;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Test {
private static MessageDigest digest = null;
public synchronized static final String hash(String data) {
if (digest == null) {
try {
digest = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException nsae) {
System.err.println(
"Failed to load the MD5 MessageDigest. "
+ "Jive will be unable to function normally.");
nsae.printStackTrace();
}
}
// Now, compute hash.
digest.update(data.getBytes());
return encodeHex(digest.digest());
}
public static final String encodeHex(byte[] bytes) {
StringBuffer buf = new StringBuffer(bytes.length * 2);
int i;

for (i = 0; i < bytes.length; i++) {
if (((int) bytes[i] & 0xff) < 0x10) {
buf.append("0");
}
buf.append(Long.toString((int) bytes[i] & 0xff, 16));
}
return buf.toString();
}
public static String test(){
return null;
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println(MD5Test.hash("123456"));
}

}

3des加密：
package com.ncs.pki.util;

import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class DesEncrypt {
/**
*
* 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
*/

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 = "";
BASE64Encoder base64en = new BASE64Encoder();
try {
byteMing = strMing.getBytes("UTF8");
byteMi = this.getEncCode(byteMing);
strMi = base64en.encode(byteMi);
} catch (Exception e) {
e.printStackTrace();
} finally {
base64en = null;
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) {
BASE64Decoder base64De = new BASE64Decoder();
byte[] byteMing = null;
byte[] byteMi = null;
String strMing = "";
try {
byteMi = base64De.decodeBuffer(strMi);
byteMing = this.getDesCode(byteMi);
strMing = new String(byteMing, "UTF8");
} catch (Exception e) {
e.printStackTrace();
} finally {
base64De = null;
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
*/
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;
}

public static void main(String[] args) {
System.out.println("des demo");
DesEncrypt des = new DesEncrypt();// 实例化一个对像
des.getKey("MYKEY");// 生成密匙
System.out.println("key=MYKEY");
String strEnc = des.getEncString("111111");// 加密字符串,返回String的密文
System.out.println("密文=" + strEnc);
String strDes = des.getDesString(strEnc);// 把String 类型的密文解密
System.out.println("明文=" + strDes);
}
}

Answer 2

md5加密小例子：

import java.security.MessageDigest;

public class StringMD5 {
private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

/**
* 转换字节数组为16进制字串
*
* @param b
* 字节数组
* @return 16进制字串
*/

public static String byteArrayToHexString(byte[] b) {
StringBuffer resultSb = new StringBuffer();
for (int i = 0; i < b.length; i++) {
resultSb.append(byteToHexString(b[i]));
}
return resultSb.toString();
}

private static String byteToHexString(byte b) {
int n = b;
if (n < 0)
n = 256 + n;
int d1 = n / 16;
int d2 = n % 16;
return hexDigits[d1] + hexDigits[d2];
}

public static String MD5Encode(String origin) {
String resultString = null;

try {
resultString = new String(origin);
MessageDigest md = MessageDigest.getInstance("MD5");
resultString = byteArrayToHexString(md.digest(resultString
.getBytes()));
} catch (Exception ex) {

}
return resultString;
}
public static void main(String[] args) {
StringMD5 test = new StringMD5();
String var = test.MD5Encode("123456");
System.out.println(var);
}
}

Answer 3

public static void jiami(String s){
//字符串长度
int n=s.length();
//定义空字符串
String jm="";
String d="";
String b="";
int k=0;
//循环字符串
for(int i=0;i<n;i++){
d=s.charAt(i)+"";
try{
k=Integer.parseInt(d);

if(k==0){
jm+=d;
jm+="_";
}
else if(k>0&&n!=(i+1)){
b=s.charAt(i+1)+"";
for(int j=0;j<k+1;j++){
jm+=b;
}
jm+="_";
}
else{
jm+=d;
}
}catch (Exception e) {
if(d.equals("_")){
jm+="\\UL";
if(n!=i+1){
jm+="_";
}
}else{
jm=jm+d;
if(n!=i+1){
jm+="_";
}
}
}
}
System.out.println("字符串长度： "+n);
System.out.println("加密: "+jm);
}
public static void main(String[] args) {
jiami("123456");
}