Android中MD5加密加鹽

MD5加密不加鹽方法:

MD5是一個安全的散列算法（Hash Functions），是哈希算法中的一種，輸入兩個不同的明文不會得到相同的輸出值。根據密文不能得到明文，其過程不可逆，也就是MD5只能用於加密認證，密文是無法解密。

代碼：

public String md5(String str) {
MessageDigest messageDigest = null;
try {
messageDigest = MessageDigest.getInstance(”MD5”);
messageDigest.reset();
messageDigest.update(str.getBytes(”UTF-8”));
} catch (NoSuchAlgorithmException e) {
System.exit(-1);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
byte[] byteArray = messageDigest.digest();
StringBuffer md5StrBuff = new StringBuffer();
for (int i = 0; i < byteArray.length; i++) {
if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
md5StrBuff.append(”0”).append(
Integer.toHexString(0xFF & byteArray[i]));
else
md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
}
return md5StrBuff.toString();
}

public String md5(String str) {
        MessageDigest messageDigest = null;
        try {
            messageDigest = MessageDigest.getInstance("MD5");
            messageDigest.reset();
            messageDigest.update(str.getBytes("UTF-8"));
        } catch (NoSuchAlgorithmException e) {
            System.exit(-1);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        byte[] byteArray = messageDigest.digest();
        StringBuffer md5StrBuff = new StringBuffer();
        for (int i = 0; i < byteArray.length; i++) {
            if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
                md5StrBuff.append("0").append(
                        Integer.toHexString(0xFF & byteArray[i]));
            else
                md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
        }
        return md5StrBuff.toString();
    }

MD5加密加鹽方法:

雖然MD5自身是不可逆，但是現在網絡上的MD5數據庫的數據量已經非常龐大，大部分常用密碼都可以通過碰撞的方法給暴力破解出來，網上比較有名的有彩虹表都能很好的破解常用MD5加密，所以一般通過加鹽的方式來提高數據的安全；

鹽值加密：把你原來密碼，加上一些鹽然後再進行一些列的加密算法。
比如你的密碼是：899312 用戶名是：jiandan
在security 中鹽值加密可以是這樣加鹽的899312{jiandan} 然後，在進行一些列的加密

代碼:

[java] view plain copy

print?

package com.itgocome.framework.security;
import java.security.MessageDigest;
import java.util.Random;
import org.apache.commons.codec.binary.Hex;
/**
* @author Rain
* @email [email protected]
* @date 2013-06-01
*/
public class PasswordUtil {
/**
* 生成含有隨機鹽的密碼
*/
public static String generate(String password) {
Random r = new Random();
StringBuilder sb = new StringBuilder(16);
sb.append(r.nextInt(99999999)).append(r.nextInt(99999999));
int len = sb.length();
if (len < 16) {
for (int i = 0; i < 16 - len; i++) {
sb.append(”0”);
}
}
String salt = sb.toString();
password = md5Hex(password + salt);
char[] cs = new char[48];
for (int i = 0; i < 48; i += 3) {
cs[i] = password.charAt(i / 3 * 2);
char c = salt.charAt(i / 3);
cs[i + 1] = c;
cs[i + 2] = password.charAt(i / 3 * 2 + 1);
}
return new String(cs);
}
/**
* 校驗密碼是否正確
*/
public static boolean verify(String password, String md5) {
char[] cs1 = new char[32];
char[] cs2 = new char[16];
for (int i = 0; i < 48; i += 3) {
cs1[i / 3 * 2] = md5.charAt(i);
cs1[i / 3 * 2 + 1] = md5.charAt(i + 2);
cs2[i / 3] = md5.charAt(i + 1);
}
String salt = new String(cs2);
return md5Hex(password + salt).equals(new String(cs1));
}
/**
* 獲取十六進制字符串形式的MD5摘要
*/
public static String md5Hex(String src) {
try {
MessageDigest md5 = MessageDigest.getInstance(”MD5”);
byte[] bs = md5.digest(src.getBytes());
return new String(new Hex().encode(bs));
} catch (Exception e) {
return null;
}
}
public static void main(String[] args) {
String password = generate(”admin”);
System.out.println(verify(”admin”, password));
}
}

package com.itgocome.framework.security;

import java.security.MessageDigest;
import java.util.Random;

import org.apache.commons.codec.binary.Hex;

/**
 * @author Rain
 * @email [email protected]
 * @date 2013-06-01
 */
public class PasswordUtil {
    /**
     * 生成含有隨機鹽的密碼
     */
    public static String generate(String password) {
        Random r = new Random();
        StringBuilder sb = new StringBuilder(16);
        sb.append(r.nextInt(99999999)).append(r.nextInt(99999999));
        int len = sb.length();
        if (len < 16) {
            for (int i = 0; i < 16 - len; i++) {
                sb.append("0");
            }
        }
        String salt = sb.toString();
        password = md5Hex(password + salt);
        char[] cs = new char[48];
        for (int i = 0; i < 48; i += 3) {
            cs[i] = password.charAt(i / 3 * 2);
            char c = salt.charAt(i / 3);
            cs[i + 1] = c;
            cs[i + 2] = password.charAt(i / 3 * 2 + 1);
        }
        return new String(cs);
    }

    /**
     * 校驗密碼是否正確
     */
    public static boolean verify(String password, String md5) {
        char[] cs1 = new char[32];
        char[] cs2 = new char[16];
        for (int i = 0; i < 48; i += 3) {
            cs1[i / 3 * 2] = md5.charAt(i);
            cs1[i / 3 * 2 + 1] = md5.charAt(i + 2);
            cs2[i / 3] = md5.charAt(i + 1);
        }
        String salt = new String(cs2);
        return md5Hex(password + salt).equals(new String(cs1));
    }

    /**
     * 獲取十六進制字符串形式的MD5摘要
     */
    public static String md5Hex(String src) {
        try {
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            byte[] bs = md5.digest(src.getBytes());
            return new String(new Hex().encode(bs));
        } catch (Exception e) {
            return null;
        }
    }

    public static void main(String[] args) {
        String password = generate("admin");
        System.out.println(verify("admin", password));
    }
}