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[原创] V&N2020 公开赛 CSRE
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发表于: 2020-3-8 16:37
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题目链接518K9s2c8@1M7s2y4Q4x3@1q4Q4x3V1k6Q4x3V1k6T1N6i4g2G2K9W2)9J5k6h3y4F1i4K6u0r3k6X3W2D9k6i4y4Q4x3V1k6T1y4r3t1%4j5X3x3I4j5$3x3%4y4U0j5@1k6X3j5@1k6r3f1K6x3e0b7@1j5U0k6W2x3o6S2T1y4o6R3K6y4q4)9J5c8V1y4e0f1X3g2Q4y4h3j5&6z5r3p5#2y4h3b7K6y4X3f1I4k6X3c8U0z5h3g2X3j5U0M7@1k6X3g2S2k6o6p5H3y4h3j5^5j5X3j5J5z5q4)9J5k6h3g2^5k6g2)9K6c8Y4c8G2K9$3g2F1i4K6y4p5k6i4W2v1x3h3x3J5g2Y4W2j5x3X3I4C8d9h3A6G2x3f1&6f1h3e0c8x3b7@1Z5H3h3W2N6r3N6q4R3J5L8r3E0u0K9Y4m8#2k6q4N6^5M7@1I4o6d9X3#2S2g2%4S2D9h3o6u0D9K9@1W2B7L8%4S2z5g2p5@1H3k6W2q4Q4x3X3g2j5L8g2y4U0e0f1q4Q4x3X3f1J5c8q4N6D9L8K6u0A6d9$3H3J5j5h3E0o6c8i4N6U0g2p5u0h3e0h3I4C8K9%4y4x3K9s2x3`.
拿到手检查一下是什么玩意：
C#程序，完事运行就是乱码，区段也不正常，加了混淆了
用
de4dot整一下，再用dnsPy查看：找到关键类：
private static void Main(string[] args)
{
if (!Class1.smethod_1())
{
return;
}
bool flag = true;
Class3 @class = new Class3();
string str = Console.ReadLine();
if (Class3.smethod_0("3" + str + "9") != "B498BFA2498E21325D1178417BEA459EB2CD28F8")
{
flag = false;
}
string text = Console.ReadLine();
string string_ = Class3.smethod_0("re" + text);
string text2 = @class.method_0(string_, "63143B6F8007B98C53CA2149822777B3566F9241");
for (int i = 0; i < text2.Length; i++)
{
if (text2[i] != '0')
{
flag = false;
}
}
if (flag)
{
Console.WriteLine("flag{" + str + text + "}");
}
}
}
还好理解，两个sha1的加密解密就行了。。
flag{1415turn}
[培训]内核驱动高级班，冲击BAT一流互联网大厂工作，每周日13:00-18:00直播授课
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