package security;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;
//import org.apache.commons.codec.binary.Hex;

/**
 * created by flyketch
 * 19-11-29 下午2:11
 */
public class MD5Test {

 public static String MD5(String input) {
 MessageDigest md5 = null;
 try {
 md5 = MessageDigest.getInstance("MD5");
 } catch (NoSuchAlgorithmException e) {
 return "check jdk";
 } catch (Exception e) {
 e.printStackTrace();
 return "";
 }
 char[] charArray = input.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();
 }

 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);
 }

 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));
 }

 private static String md5Hex(String src) {
 try {
 MessageDigest md5 = MessageDigest.getInstance("MD5");
 byte[] bs = md5.digest(src.getBytes());
// return new String(new Hex().encode(bs));
 return bs.toString();
 } catch (Exception e) {
 return null;
 }
 }

 public static void main(String args[]) {

 String plaintext = "DingSai";

 System.out.println("明文:" + plaintext);
 System.out.println("普通MD5码:" + MD5(plaintext));

 // 获取加盐后的MD5值
 String ciphertext = generate(plaintext);
 System.out.println("加盐后MD5码:" + ciphertext);
 System.out.println("是否是同一字符串:" + verify(plaintext, ciphertext));

 }

}