MD5/SHA256/SHA512加密算法

MD5和SHA算法可以生成一串字符串摘要（digest），可用于加密及文件内容对比。

package com.drz.proxy.internetProxy.util;

import java.io.File;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.codec.digest.MessageDigestAlgorithms;

/**
 *  MD5算法可以用来对密码加密、比较文件内容
 *  MD5 用16进制数表示128位，生成的字符是32个（4个二进制位表示一个十六进制数）
 *  SHA1 是 160 位 ，SHA256 是 256 位，SHA512 是512 位
 * @author os-dingrz
 *
 */
public class VerifyFile {

    public static void main(String[] args) throws Exception {
        String password = "123456789";
        String salt = "zrd";

        String hexByMD5 = new DigestUtils(MessageDigestAlgorithms.MD5).digestAsHex(password);//不加盐
        System.out.println(hexByMD5);
        String secuHexByMD5 = getSecurePassword(password, salt, MessageDigestAlgorithms.MD5);
        System.out.println(secuHexByMD5);

        String hexBySHA256 = new DigestUtils(MessageDigestAlgorithms.SHA_256).digestAsHex(password);//不加盐
        System.out.println(hexBySHA256);
        String hexBySHA256ByMD5 = getSecurePassword(password, salt, MessageDigestAlgorithms.SHA_256);
        System.out.println(hexBySHA256ByMD5);

        //比较文件内容是否相同,与此文件名无关
        File file2 = new File("D:/ztest.zip");
        String hex2 = new DigestUtils(MessageDigestAlgorithms.SHA_512).digestAsHex(file2);
        System.out.println(hex2);
        File file3 = new File("D:/ztest2.zip");
        String hex3 = new DigestUtils(MessageDigestAlgorithms.SHA_512).digestAsHex(file3);
        System.out.println(hex3);
    }

    public static String getSecurePassword(String passwordToHash, String salt, String algtype)
            throws UnsupportedEncodingException {
        String generatedPassword = null;
        try {
            MessageDigest md = MessageDigest.getInstance(algtype);
            md.update(salt.getBytes("UTF-8"));
            byte[] bytes = md.digest(passwordToHash.getBytes("UTF-8"));
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < bytes.length; i++) {
                sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));
            }
            generatedPassword = sb.toString();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return generatedPassword;
    }
}

执行结果：

25f9e794323b453885f5181f1b624d0b
d79f0f80e4ac19c784c95727a101715e
15e2b0d3c33891ebb0f1ef609ec419420c20e320ce94c65fbc8c3312448eb225
476a9e9395799fb7a03bec9137c9761bf9144d48ecdfe059ac8be6df25cc8d98
cfd9a55957a2e5b5f7908db88451e1e1495089a57a7fdb1e7b24388ce239535d0d9c42082c8a156094e9db484913458dbf5acfa48c50023975c7a1489f340bdc
cfd9a55957a2e5b5f7908db88451e1e1495089a57a7fdb1e7b24388ce239535d0d9c42082c8a156094e9db484913458dbf5acfa48c50023975c7a1489f340bdc