MD5哈希更快

Question

我有一個單詞表，其中來自20級的〜68000個單詞，位於0xf.at處，並且想要散列兩個單詞以獲得散列。然後將該散列與現有散列進行比較，直到找到兩個單詞。

我已經在java中嘗試過了，但我沒有意識到它是慢的。

import java.io.*; 

public class Main { 

public static void main(String[] args) throws FileNotFoundException, 
     IOException { 

    try (BufferedReader br = new BufferedReader(new FileReader("E:/Trojan/Desktop/wordlist.txt"))) { 
     StringBuilder sb = new StringBuilder(); 
     String line = br.readLine(); 
     Hash h = new Hash(); 
     String myHash = "cd48323bcf01557f5deadc2ec301affb"; 
     while (line != null) { 
      sb.append(line); 
      sb.append(System.lineSeparator()); 
      line = br.readLine(); 
     } 
     String everything = sb.toString(); 
     String lines[] = everything.split("\\r?\\n"); 
     for (int j = 1; j <= 68848; j++) { 
      for (int i = 1; i <= 68847; i++) { 
       //System.out.println(i+":"+lines[i]+" "+j+":"+lines[j]); 
       if (h.getHash(lines[i]+lines[j], "MD5") == myHash){ 
        System.out.println(lines[i]+lines[j]); 
        break; 
       } 
      } 
     } 
    } 
} 
} 

和MD5哈希函數我從計算器的〔實施例了：

public class Hash { 
/** 
* 
* @param txt, text in plain format 
* @param hashType MD5 OR SHA1 
* @return hash in hashType 
*/ 
public static String getHash(String txt, String hashType) { 
    try { 
       java.security.MessageDigest md = java.security.MessageDigest.getInstance(hashType); 
       byte[] array = md.digest(txt.getBytes()); 
       StringBuffer sb = new StringBuffer(); 
       for (int i = 0; i < array.length; ++i) { 
        sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1,3)); 
      } 
       return sb.toString(); 
     } catch (java.security.NoSuchAlgorithmException e) { 
      //error action 
     } 
     return null; 
} 

public static String md5(String txt) { 
    return Hash.getHash(txt, "MD5"); 
} 

public static String sha1(String txt) { 
    return Hash.getHash(txt, "SHA1"); 
} 
} 

我怎樣才能得到這個更快？

Answer 1

在方法getHash中創建了太多的臨時對象。嘗試減少。例如。

private static final char[] HEX ={'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f',}; 
public static String getHash(String txt, MessageDigest md) { 
    byte[] array = md.digest(txt.getBytes()); 
    char[] result = new char[array.length*2]; 
    for (int i = 0; i < array.length; ++i) { 
     byte b = array[i]; 
     result[2*i] = HEX[(b&0x0f0)>>>4]; 
     result[2*i+1] = HEX[b&0x0f]; 
    } 
    return new String(result); 
} 

編輯 而且你不需要String對象的。您應該返回byte []並使用Arrays.equals方法。