Sean Park Posted January 1, 2022 Share Posted January 1, 2022 View File Sean's KeyGenMe - Simple Tricks I coded a keygenme, simple tricks. I hope you enjoy your time trying to solve this! Submitter Sean Park Submitted 01/01/2022 Category KeygenMe Link to comment Share on other sites More sharing options...
Washi Posted January 1, 2022 Share Posted January 1, 2022 (edited) Example keys: Spoiler washi: B604404A000831E195B4291B3F35A23F5B6B7592 tuts4you: DD6850E979CB255113546C9F0045C863B63CE83100497814DD6850E900497814 Approach: Spoiler Problem with this keygenme is that the input serial key is compared to the correct serial key directly using string comparison. This means the app generates a correct serial itself, which means the "only" thing to do is finding this algorithm in a decompiler and copy it for a keygen. Open in Ghidra, notice it's an MFC app so no "obvious" entrypoint Run app, notice app shows a message box after a bad input was put in. XRef for MessageBoxW calls and find function FUN_004019b0 which contains both the serial generation algorithm , as well as the two good and bad boy messagebox calls. Algorithm is pretty simple: For every character c, compute c^5 * j, where j is any number between 1 and 0x91. The results are concatenated using an uppercase hex format. Final string is reversed. If any of these j's work, then it is a valid serial. For a keygen, just pick a random j and do exactly the same to produce a serial: keygen.py Edited January 1, 2022 by Washi 2 Link to comment Share on other sites More sharing options...
Sean Park Posted January 2, 2022 Author Share Posted January 2, 2022 Washi. Conratulations. You fully analyzed the algorithm of my keygenme. Thank you for your attention. regards. sean. Link to comment Share on other sites More sharing options...
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