数字6桁のMD5ハッシュ値総当り

CrackHash.java

package com.example;

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

/**
 * <a href="https://commons.apache.org/proper/commons-codec/">Apache Commons Codec</a>使用
 * 
 * http://z.tokumaru.org/2014/02/6php025.html
 */
public class CrackHash {

    public static void main(String[] args) throws Exception {
        String hashed = "4b364677946ccf79f841114e73ccaf4f";
        String salt = "hoge";
        CrackHash c = new CrackHash();

        long start = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            StringBuilder sb = new StringBuilder();
            sb.append(salt);
            sb.append("$");
            sb.append(c.filledZero(i, 6));
            if (hashed.equals(DigestUtils.md5Hex(sb.toString().getBytes()))) {
                System.out.println("found: " + sb.toString());
                break;
            }
        }
        System.out.println(System.currentTimeMillis() - start);
    }

    private String filledZero(int num, int totalLength) {
        String strNum = String.valueOf(num);
        int numLen = strNum.length();
        if (numLen >= totalLength) {
            return strNum;
        }

        StringBuilder sb = new StringBuilder();
        for (int i = numLen; i < totalLength; i++) {
            sb.append("0");
        }
        sb.append(strNum);
        return sb.toString();
    }

}