Union CTF 2021 (I): exah

I was playing Union CTF with @blackb6a last week. Since this CTF is prepared by cr0wn where Jack and hyperreality were in (they made CryptoHack), I am convinced that the CTF will be fun. Turns out I wasn’t disappointed at all. I will be writing three or four posts on the challenges, and the first of the series covers on exah, the reversing challenge I spent most of my time (yet not solving it).
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kurenaif 1K Subscriptions Challenges

kurenaif 1K Subscriptions Challenges
On 13 February, 2021, kurenaif has released five challenges celebrating the 1000-subscription in the YouTube channel. Being locked at home in Lunar New Year, I have nothing else to do. Therefore I decided to attempt those challenges, which is available on GitHub.
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DiceCTF 2021 Writeup (I)

DiceCTF 2021 Writeup (I)
DiceCTF 2021 had an assortment of challenges and most of them are tough. Although the five crypto challenges which looked unoriginal, I was only able to solve garbled during the contest and I liked the challenges very much. After the CTF, I have found writeups from various sources and learnt a lot. In this writeup, only plagiarism and benaloh will be covered. However, I haven’t look at the remaining questions yet, and they are definitely on my to-do list.
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justCTF 2020: Oracles

justCTF 2020: Oracles
I was playing justCTF 2020 with the new CTFers in Yakitori (Firebird). Oracles is a fun cryptography challenge that I solved during the game, and I thought this is worth compiling the write-up.
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hoifanrd’s osu! Challenge

hoifanrd's osu! Challenge
This is a beginning of a new series of blog posts that I review CTF challenges those are not publicly accessible. Generally I will spend some time to solve the challenge while discussing with the author, and give some feedback of the challenge. To kick-start, let’s look at hoifanrd from Firebird CTF team has shared a challenge he created some days ago.
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