Tags: mac-forgery sha-1 

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TLDR: Length extension attack on SHA1. Use `https://github.com/stephenbradshaw/hlextend` to extend the known msg. Since key length is unknown, iterate through keylengths from 10 to 109 until we hit a match. Use that key length to submit the forged message.

https://meashiri.github.io/ctf-writeups/posts/202306-nahamcon/#forge-me-2

Original writeup (https://meashiri.github.io/ctf-writeups/posts/202306-nahamcon/#forge-me-2).