是否有某种方式可以优化此代码以使其运行更快？

Question

我正在编写一个程序来获取MD5哈希值并针对dictionary.txt文件运行它。如果我只运行文件中的单词，它会很快破解它，但是如果我添加一个特殊字符，则大约需要10分钟才能破解。有什么方法可以使其运行更快？ 如果我运行$ hello（932d24e18f06b12e7a867425d51c909a）的MD5哈希，则大约需要10分钟才能破解。

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;

public class Cracker extends verify {

    private static String specialCharacters = "@#$%&";

    public static void main(String[] args) {
        List<String> dictionaryWords = new LinkedList<>();
        try {
            Scanner s = new Scanner(new File("data/dictionary.txt"));
            while (s.hasNext()) {
                dictionaryWords.add(s.next());
            }
            s.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        Scanner s = new Scanner(System.in);
        System.out.println("Enter the password MD5 hash to crack:");
        String md5target = s.nextLine();
        s.close();
        long startTime = new Date().getTime();
        boolean cracked = false;
        System.out.println("Trying to crack it with type 1 attack");
        for (String word : dictionaryWords) {
            //if (MD5.md5(word).equals(md5target)) {
            if (MD5.md5(word).equals(md5target))  { 
                System.out.println("Password is " + word);
                cracked = true;
                break;
            }
        }
        if (!cracked) {
            System.out.println("No matches in dictionary. Start looking for type 2 password");
            outer: for (String word : dictionaryWords) {
                List<String> combinationsForDictionaryWord = generateAllType2CombinationsForWord(word);
                for (String generatedWord : combinationsForDictionaryWord) {
                    if (MD5.md5(generatedWord).equals(md5target)) {
                        System.out.println("Password is " + generatedWord);
                        cracked = true;
                        break outer;
                    }
                }
            }
            if (!cracked) {
                System.out.println("The password is not type 2 password. Not cracked");
            }
        }
        if (cracked) {
            System.out.println("Total time:" + (new Date().getTime() - startTime) / 1000.0 + " s");
        }
    }

    private static List<String> generateAllType2CombinationsForWord(String word) {
        List<String> combinations = new LinkedList<>();
        List<String> oneLetterCombinations = new LinkedList<>();
        // all combinations with 1 letter
        for (int i = 0; i <= word.length(); i++) {
            for (char ch = '0'; ch <= '9'; ch++) {
                oneLetterCombinations.add(new StringBuffer(word).insert(i, ch).toString());
            }
            for (int j = 0; j < specialCharacters.length(); j++) {
                oneLetterCombinations.add(new StringBuffer(word).insert(i, specialCharacters.charAt(j)).toString());
            }
        }
        combinations.addAll(oneLetterCombinations);
        List<String> twoLetterCombinations = new LinkedList<>();
        // all combinations with two letters
        for (String sourceWord : oneLetterCombinations) {
            for (int i = 0; i <= sourceWord.length(); i++) {
                for (char ch = '0'; ch <= '9'; ch++) {
                    twoLetterCombinations.add(new StringBuffer(sourceWord).insert(i, ch).toString());
                }
                for (int j = 0; j < specialCharacters.length(); j++) {
                    twoLetterCombinations
                            .add(new StringBuffer(sourceWord).insert(i, specialCharacters.charAt(j)).toString());
                }
            }
        }
        combinations.addAll(twoLetterCombinations);

        return combinations;
    }

}
'''