This repository contains official source code and writeups for challenges from SekaiCTF 2025.

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Blockchains

Name	Author	Difficulty	Solves
Sekai Meme Launcher*	snwo	2⯁ (Normal)	13
Sekai Lending*	snwo	3⯁ (Hard)	11
Stray Cat*	Quasar	4⯁ (Expert)	8
チケットマスター (Ticket Master)*	Y4nhu1	5⯁ (Master)	3

Cryptography

Name	Author	Difficulty	Solves
SSSS	Utaha	1⯁ (Easy)	236
I Dream of Genni	Neobeo	2⯁ (Normal)	124
Alter Ego	kanon	3⯁ (Hard)	7
APES	Neobeo	4⯁ (Expert)	3
Law And Order*	deuterium	4⯁ (Expert)	0
unfairy-ring*	Neobeo, Sceleri	5⯁ (Master)	0
unfairy-ring++*	Sceleri, Neobeo	6✦ (Append)	0

Miscellaneous

Name	Author	Difficulty	Solves
Discrepancy	Legoclones	2⯁ (Normal)	104
Literal Eval	Sceleri	3⯁ (Hard)	15
Sekai Bank - Transaction	Marc	4⯁ (Expert)	17

PPC

Name	Author	Difficulty	Solves
Nokotan's Arcade	sahuang	1⯁ (Easy)	390
Nokotan's Antler Tines	null_awe	3⯁ (Hard)	37
Nokotan's Guidance	null_awe	4⯁ (Expert)	124

Binary Exploitation

Name	Author	Difficulty	Solves
speedpwn 2	Zafirr	1⯁ (Easy)	42
Learning OOP	Zafirr	2⯁ (Normal)	50
Outdated	Legoclones	3⯁ (Hard)	27
Umiyuri Kaikeitan	nyancat0131	4⯁ (Expert)	5
vkfs	Segal, Zafirr	5⯁ (Master)	2
WIC*	4n0nym4u5	6✦ (Append)	0

Reverse Engineering

Name	Author	Difficulty	Solves
Sekai Bank - Signature	Marc	1⯁ (Easy)	215
Gondola	3dsboy08, es3n1n	2⯁ (Normal)	81
sekai-craft*	es3n1n	2⯁ (Normal)	35
Miku Music Machine	molenzwiebel	3⯁ (Hard)	30
Alchemy Master	es3n1n	4⯁ (Expert)	8
What in Ternation	molenzwiebel	4⯁ (Expert)	7

Web

Name	Author	Difficulty	Solves
My Flask App	belugagemink	1⯁ (Easy)	451
Fancy Web	DimasMaulana	2⯁ (Normal)	0
vite	irogir	2⯁ (Normal)	1
hqli-me	irogir	3⯁ (Hard)	3
Notebook Viewer	Qyn	3⯁ (Hard)	11
Captivating Canvas Contraption*	Qyn	4⯁ (Expert)	1
rednote	strellic	4⯁ (Expert)	4

Bounties

Challenges marked with an asterisk (*) were eligible for bounties during the CTF. For certain unsolved challenges, the bounty remained available after the competition concluded:

Category	Name	Difficulty	Solves	Bounty
Cryptography	Law And Order	4⯁ (Expert)	0	(Bad handout) $400
Binary Exploitation	WIC	6✦ (Append)	0	$200
Cryptography	unfairy-ring++	6✦ (Append)	0	$200
Blockchains	チケットマスター	5⯁ (Master)	3	$100, $50, $30
Blockchains	Stray Cat	4⯁ (Expert)	8	$100, $50, $30
Blockchains	Sekai Lending	3⯁ (Hard)	11	$100, $50, $30
Blockchains	Sekai Meme Launcher	2⯁ (Normal)	13	$100, $50, $30
Cryptography	unfairy-ring	5⯁ (Master)	0	$100
Reverse Engineering	sekai-craft	2⯁ (Normal)	35	(Fastest run) $50
Web	Captivating Canvas Contraption	4⯁ (Expert)	1	$50

License

Any program and/or source code in this repository is licensed under the GNU Affero General Public License version 3:

SEKAI CTF 2025 Challenges and Solutions
Copyright (C) 2025 Project SEKAI CTF team and contributors

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with this program. If not, see https://www.gnu.org/licenses/.

Any non-code/program content (writeups, READMEs, descriptions) in this repository is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0):

SEKAI CTF 2025 Challenges and Solutions by Project SEKAI CTF team and contributors is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.