Java的MD5加密和解密

2024-10-19 02:45:57

链接：http://www.cnblogs.com/android-blogs/p/5305598.html

Java的MD5加密和解密

简单demo:

import java.security.*;
import java.security.spec.*;
class MD5_test {
public final static String MD5(String s) {
char hexDigits[] = { '0' , '1' , '2' , '3' , '4' , '5' , '6' , '7' , '8' , '9' ,
'a' , 'b' , 'c' , 'd' , 'e' , 'f' };
try {
byte [] strTemp = s.getBytes();
MessageDigest mdTemp = MessageDigest.getInstance("MD5" );
mdTemp.update(strTemp);
byte [] md = mdTemp.digest();
int j = md.length;
char str[] = new char [j * 2 ];
int k = 0 ;
for ( int i = 0 ; i < j; i++) {
byte byte0 = md[i];
str[k++] = hexDigits[byte0 >>> 4 & 0xf ];
str[k++] = hexDigits[byte0 & 0xf ];
}
return new String(str);
} catch (Exception e) {
return null ;
}
}
public static void main(String[] args) {
// MD5_Test aa = new MD5_Test();
System.out.print(MD5_test.MD5("b" ));
}
}

import java.security.*;
import java.security.spec.*;
class MD5_test {
public final static String MD5(String s) {
char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f' };
try {
byte[] strTemp = s.getBytes();
MessageDigest mdTemp = MessageDigest.getInstance("MD5");
mdTemp.update(strTemp);
byte[] md = mdTemp.digest();
int j = md.length;
char str[] = new char[j * 2];
int k = 0;
for (int i = 0; i < j; i++) {
byte byte0 = md[i];
str[k++] = hexDigits[byte0 >>> 4 & 0xf];
str[k++] = hexDigits[byte0 & 0xf];
}
return new String(str);
} catch (Exception e) {
return null;
}
}
public static void main(String[] args) {
// MD5_Test aa = new MD5_Test();
System.out.print(MD5_test.MD5("b"));
}
}

import java.security.MessageDigest;
public class MD5andKL {
// MD5加码。32位
public static String MD5(String inStr) {
MessageDigest md5 = null ;
try {
md5 = MessageDigest.getInstance("MD5" );
} catch (Exception e) {
System.out.println(e.toString());
e.printStackTrace();
return "" ;
}
char [] charArray = inStr.toCharArray();
byte [] byteArray = new byte [charArray.length];
for ( int i = 0 ; i < charArray.length; i++)
byteArray[i] = (byte ) charArray[i];
byte [] md5Bytes = md5.digest(byteArray);
StringBuffer hexValue = new StringBuffer();
for ( int i = 0 ; i < md5Bytes.length; i++) {
int val = (( int ) md5Bytes[i]) & 0xff ;
if (val < 16 )
hexValue.append("0" );
hexValue.append(Integer.toHexString(val));
}
return hexValue.toString();
}
// 可逆的加密算法
public static String KL(String inStr) {
// String s = new String(inStr);
char [] a = inStr.toCharArray();
for ( int i = 0 ; i < a.length; i++) {
a[i] = (char ) (a[i] ^ 't' );
}
String s = new String(a);
return s;
}
// 加密后解密
public static String JM(String inStr) {
char [] a = inStr.toCharArray();
for ( int i = 0 ; i < a.length; i++) {
a[i] = (char ) (a[i] ^ 't' );
}
String k = new String(a);
return k;
}
// 测试主函数
public static void main(String args[]) {
String s = new String( "a" );
System.out.println("原始：" + s);
System.out.println("MD5后：" + MD5(s));
System.out.println("MD5后再加密：" + KL(MD5(s)));
System.out.println("解密为MD5后的：" + JM(KL(MD5(s))));
}
}

import java.security.MessageDigest;
public class MD5andKL {
// MD5加码。32位
public static String MD5(String inStr) {
MessageDigest md5 = null;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (Exception e) {
System.out.println(e.toString());
e.printStackTrace();
return "";
}
char[] charArray = inStr.toCharArray();
byte[] byteArray = new byte[charArray.length];
for (int i = 0; i < charArray.length; i++)
byteArray[i] = (byte) charArray[i];
byte[] md5Bytes = md5.digest(byteArray);
StringBuffer hexValue = new StringBuffer();
for (int i = 0; i < md5Bytes.length; i++) {
int val = ((int) md5Bytes[i]) & 0xff;
if (val < 16)
hexValue.append("0");
hexValue.append(Integer.toHexString(val));
}
return hexValue.toString();
}
// 可逆的加密算法
public static String KL(String inStr) {
// String s = new String(inStr);
char[] a = inStr.toCharArray();
for (int i = 0; i < a.length; i++) {
a[i] = (char) (a[i] ^ 't');
}
String s = new String(a);
return s;
}
// 加密后解密
public static String JM(String inStr) {
char[] a = inStr.toCharArray();
for (int i = 0; i < a.length; i++) {
a[i] = (char) (a[i] ^ 't');
}
String k = new String(a);
return k;
}
// 测试主函数
public static void main(String args[]) {
String s = new String("a");
System.out.println("原始：" + s);
System.out.println("MD5后：" + MD5(s));
System.out.println("MD5后再加密：" + KL(MD5(s)));
System.out.println("解密为MD5后的：" + JM(KL(MD5(s))));
}
}

失败是什么？没有什么，只是更走近成功一步；成功是什么？就是走过了所有通向失败的路，只剩下一条路，那就是成功的路。

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