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对于md5与sha1的强弱碰撞

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本文是对于知识点的总结，md5()和sha1()碰撞应该全在这了

a==b:弱类型比较会将a和b转成统一数据类型在进行比较，

a===b:强类型比较会先判断a和b是不是相同类型，不是，则返回false，是，再比较a和b的值。

未过滤数组

这个绕过是万能钥匙，对于强弱类型的都可适用

对于md5绕过

比如

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if ( $_POST['param1'] !==$_POST['param2'] && md5($_POST['param1']) === md5($_POST['param2']))
{
echo "flag";
}

Payload:

?param1[]=1&param2[]=2

还有另一种方法，0e开头的md5也可以绕过

例如：

QNKCDZO

0e830400451993494058024219903391

240610708

0e462097431906509019562988736854

s878926199a

0e545993274517709034328855841020

s155964671a

0e342768416822451524974117254469

s214587387a

0e848240448830537924465865611904

s214587387a

0e848240448830537924465865611904

s878926199a

0e545993274517709034328855841020

s1091221200a

0e940624217856561557816327384675

s1885207154a

0e509367213418206700842008763514

s1502113478a

0e861580163291561247404381396064

s1885207154a

0e509367213418206700842008763514

s1836677006a

0e481036490867661113260034900752

s155964671a

0e342768416822451524974117254469

s1184209335a

0e072485820392773389523109082030

s1665632922a

0e731198061491163073197128363787

s1502113478a

0e861580163291561247404381396064

s1836677006a

0e481036490867661113260034900752

s1091221200a

0e940624217856561557816327384675

s155964671a

0e342768416822451524974117254469

s1502113478a

0e861580163291561247404381396064

s155964671a

0e342768416822451524974117254469

s1665632922a

0e731198061491163073197128363787

s155964671a

0e342768416822451524974117254469

s1091221200a

0e940624217856561557816327384675

s1836677006a

0e481036490867661113260034900752

s1885207154a

0e509367213418206700842008763514

s532378020a

0e220463095855511507588041205815

s878926199a

0e545993274517709034328855841020

s1091221200a

0e940624217856561557816327384675

s214587387a

0e848240448830537924465865611904

s1502113478a

0e861580163291561247404381396064

s1091221200a

0e940624217856561557816327384675

s1665632922a

0e731198061491163073197128363787

s1885207154a

0e509367213418206700842008763514

s1836677006a

0e481036490867661113260034900752

s1665632922a

0e731198061491163073197128363787

s878926199a

0e545993274517709034328855841020

原理：

md5()函数无法处理数组，如果传入的为数组，会返回NULL，所以两个数组经过加密后得到的都是NULL,也就是相等的。

如果两个字符经MD5加密后为0exxxxx形式会被认为是科学计数法表示0*10的xxxx次方，值为零所以相等

sha1()函数也无法处理数组，于md5等价

过滤数组

过滤了数组后就比较难搞

sha1()绕过

user=%25PDF-1.3%0A%25%E2%E3%CF%D3%0A%0A%0A1%200%20obj%0A%3C%3C/Width%202%200%20R/Height%203%200%20R/Type%204%200%20R/Subtype%205%200%20R/Filter%206%200%20R/ColorSpace%207%200%20R/Length%208%200%20R/BitsPerComponent%208%3E%3E%0Astream%0A%FF%D8%FF%FE%00%24SHA-1%20is%20dead%21%21%21%21%21%85/%EC%09%239u%9C9%B1%A1%C6%3CL%97%E1%FF%FE%01%7FF%DC%93%A6%B6%7E%01%3B%02%9A%AA%1D%B2V%0BE%CAg%D6%88%C7%F8K%8CLy%1F%E0%2B%3D%F6%14%F8m%B1i%09%01%C5kE%C1S%0A%FE%DF%B7%608%E9rr/%E7%ADr%8F%0EI%04%E0F%C20W%0F%E9%D4%13%98%AB%E1.%F5%BC%94%2B%E35B%A4%80-%98%B5%D7%0F%2A3.%C3%7F%AC5%14%E7M%DC%0F%2C%C1%A8t%CD%0Cx0Z%21Vda0%97%89%60k%D0%BF%3F%98%CD%A8%04F%29%A1

pass=%25PDF-1.3%0A%25%E2%E3%CF%D3%0A%0A%0A1%200%20obj%0A%3C%3C/Width%202%200%20R/Height%203%200%20R/Type%204%200%20R/Subtype%205%200%20R/Filter%206%200%20R/ColorSpace%207%200%20R/Length%208%200%20R/BitsPerComponent%208%3E%3E%0Astream%0A%FF%D8%FF%FE%00%24SHA-1%20is%20dead%21%21%21%21%21%85/%EC%09%239u%9C9%B1%A1%C6%3CL%97%E1%FF%FE%01sF%DC%91f%B6%7E%11%8F%02%9A%B6%21%B2V%0F%F9%CAg%CC%A8%C7%F8%5B%A8Ly%03%0C%2B%3D%E2%18%F8m%B3%A9%09%01%D5%DFE%C1O%26%FE%DF%B3%DC8%E9j%C2/%E7%BDr%8F%0EE%BC%E0F%D2%3CW%0F%EB%14%13%98%BBU.%F5%A0%A8%2B%E31%FE%A4%807%B8%B5%D7%1F%0E3.%DF%93%AC5%00%EBM%DC%0D%EC%C1%A8dy%0Cx%2Cv%21V%60%DD0%97%91%D0k%D0%AF%3F%98%CD%A4%BCF%29%B1

参考连接

https://blog.csdn.net/heiseweiye/article/details/82735640?spm=1001.2101.3001.6661.1&utm_medium=distribute.pc_relevant_t0.none-task-blog-2%7Edefault%7ECTRLIST%7Edefault-1.no_search_link&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-2%7Edefault%7ECTRLIST%7Edefault-1.no_search_link

md5绕过

param1=

%D89%A4%FD%14%EC%0EL%1A%FEG%ED%5B%D0%C0%7D%CAh%16%B4%DFl%08Z%FA%1DA%05i%29%C4%FF%80%11%14%E8jk5%0DK%DAa%FC%2B%DC%9F%95ab%D2%09P%A1%5D%12%3B%1ETZ%AA%92%16y%29%CC%7DV%3A%FF%B8e%7FK%D6%CD%1D%DF/a%DE%27%29%EF%08%FC%C0%15%D1%1B%14%C1LYy%B2%F9%88%DF%E2%5B%9E%7D%04c%B1%B0%AFj%1E%7Ch%B0%96%A7%E5U%EBn1q%CA%D0%8B%C7%1BSP

&param2=

%D89%A4%FD%14%EC%0EL%1A%FEG%ED%5B%D0%C0%7D%CAh%164%DFl%08Z%FA%1DA%05i%29%C4%FF%80%11%14%E8jk5%0DK%DAa%FC%2B%5C%A0%95ab%D2%09P%A1%5D%12%3B%1ET%DA%AA%92%16y%29%CC%7DV%3A%FF%B8e%7FK%D6%CD%1D%DF/a%DE%27%29o%08%FC%C0%15%D1%1B%14%C1LYy%B2%F9%88%DF%E2%5B%9E%7D%04c%B1%B0%AFj%9E%7Bh%B0%96%A7%E5U%EBn1q%CA%D0%0B%C7%1BSP

或者

a=M%C9h%FF%0E%E3%5C%20%95r%D4w%7Br%15%87%D3o%A7%B2%1B%DCV%B7J%3D%C0x%3E%7B%95%18%AF%BF%A2%00%A8%28K%F3n%8EKU%B3_Bu%93%D8Igm%A0%D1U%5D%83%60%FB_%07%FE%A2

&b=M%C9h%FF%0E%E3%5C%20%95r%D4w%7Br%15%87%D3o%A7%B2%1B%DCV%B7J%3D%C0x%3E%7B%95%18%AF%BF%A2%02%A8%28K%F3n%8EKU%B3_Bu%93%D8Igm%A0%D1%D5%5D%83%60%FB_%07%FE%A2

参考链接

https://blog.csdn.net/weixin_30877493/article/details/99558878

MD5奇奇怪怪的知识

md5构造脚本

筛选已经替md5中’cxhp’为’0123’后开头为’0e’的密文

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<?php
 for($a = 1; $a <= 100000000; $a++) {
   $md5 = strtr(md5($a),'cxhp', '0123');
  if(preg_match('/^0e\d+$/', $md5)) {
    echo $a;
    echo "\n";
    echo $md5;
    echo "\n";
  }
 }
 ?>

该脚本筛选以ce开头的md5密文

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<?php
for($a=1;$a<=1000000000;$a++){
   $md5 = md5($a);
   if(preg_match('/^ce\d+$/',$md5)){
      echo $a;
      echo "\n";
      echo $md5;
      echo "\n";
   }
}
?>

md5加密前后都是0e开头

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def run():
    i = 0
    while True:
        text = '0e{}'.format(i)
        m = md5(text)
        print(text,m)
        if m[0:2] == '0e' :
            if m[2:].isdigit():
                print('find it:',text,":",m)
                break
        i +=1

run()

跑出来的结果为0e215962017