New Challenge "A Salute to Prof. Zhang"

Linux Challenges Removed

You can play Bandit instead

Flag fixed for "Baby ECC (1) Elliptic Curve"

If you were stuck before, please try again.

"A Taste of Crypto Mining" modified, increased difficulty

Web Challenges are back online!

Thanks to the great help from elemental.unicorn. We have web challenges back online.

Checkout this cool challenge "Kevin's No Good, Very Bad Day" (Web)

Web challenges are offline

We are migrating the server for web challenges.

"Baby RSA (3) and (5)" hint and flag were wrong. Please redo the challenge.

The hint for how to calculate totient was wrong. It affected the "d" value too. But other RSA problems are magically not affected.

Linux Lab is migrating

The server might lose contact briefly.

US middle schoolers who ranked top 150, please DM @Happysaur by 5PM PST.

"Baby Equations" fixed.

`Baby Equations`, `General Han Xin`, `Folded 10 times` released.

All 0-point reverse.

Kevin just tweeted

See Kevin's latest tweet

Calling top 10

As the ranks for the top 10 players won't change any more. If you are among the top 10 and currently in a US middle school (or elementary school), please DM @Happysaur.

Plan for this site after Fweefwop CTF 2021

Thanks to (, their CEO, Kevin, granted us education discount. So we will keep the server up for training after this CTF. New problems will be added from time to time. You are welcomed to come back and train with us.

The last batch of 8 challenges has been released!

"Where's the message?" -- added a new hint

"Tell Kevin What you Think! " Released

"Strange RSA" released

Two new problems released

Where's the message? - Wirebirds (both crypto) have been released

New Challenges will stop being released in 3 days

This CTF ends at 8 AM 10/31 PST. To help others catch up, we will stop releasing new challenges 24 hours before it ends.

Three new problems released

Silly Secret Sharing(SSS) - Crypto Modular Math(3) - General Modular Math(4) - General

"Smashed" (Forensics) released

"Open Secret" Released

"2B, or not 2B!" Released

We have 300 players!


Bitcoin Laundering (2) released! It's OSINT