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B-SIDE

A daily CTF challenge with a fun new puzzle every day

What is B-SIDE?

This side program features challenges with a different flavor from Daily AlpacaHack. We publish one harder or more unconventional challenge every few days.

Join Anytime

Solve each challenge within its time window to appear on the leaderboard.

Not a Competition

Discussion with friends or AI is welcome (account sharing is prohibited).

Solution Sharing Rules

Sharing solutions is allowed only after the challenge period has ended.

New to CTFs?

This program features higher difficulty and unconventional challenges. Try the beginner-friendly Daily AlpacaHack first to warm up.

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Today's Challenge
minaminaominaminao
Long Flag Printer 2026
Misc
Medium
16 solves
Submissions (latest 3)
toomer

SOLVED!

Jul 18, 8:47 PM

nakamulab

SOLVED!

Jul 18, 8:38 PM

tyage

SOLVED!

Jul 18, 12:17 PM

Leaderboard
Upcoming challenges reveal the , , and in advance.
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Jul 2026

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tan90909090tan90909090
New Directory
Misc
Hard
25 solves
1-5
minaminaominaminao
missing ✌️
Crypto
Hard
31 solves
6-11
pppp4649pppp4649
Re:Small e
Crypto
Very Hard
25 solves
12-16
colza
kappa maki
Pwn
Hard
34 solves
 
colza
kappa maki
Pwn
Hard
34 solves
17-21
minaminaominaminao
Long Flag Printer 2026
Misc
Medium
16 solves
 
minaminaominaminao
Long Flag Printer 2026
Misc
Medium
16 solves
22-26
minaminaominaminao
Planned topicMAC
Crypto
Hard
27
Coming soon
28
Coming soon
29
Coming soon
30
Coming soon
31
Coming soon
1
Coming soon
2
Coming soon

Writeups

ojun

Writeup for kappa maki

ojun

ja
kappa maki

2026/07/18 09:11

kirehash

Writeup for invisible-grep

ja

2026/07/14 13:25

tchen

Writeup for InstaTalk

author
en

2026/07/06 07:37

Rows:

Anti Timing Attack

Topic: NetworkReleased: Apr 13, 2026

30 solves
Misc
Hard6.5

by

kakur41

kakur41

Writeups

kirehash

Writeup for Anti Timing Attack

kirehash

ja

2026/04/21 00:05



tadanobutubutu

Writeup for Anti Timing Attack

ja

2026/04/16 23:52

descriptionsolveswriteups