My CTF Challenges

This is some challenges I created for CTF competitions.

TSJ CTF 2022

It is recommended to read Crypto writeups here, because it supports math rendering. 2022/05/22: GitHub supports MathJax rendering on GitHub now, but it still have some compatibility issues, so you might still want to use the url above when having issues.

Name	Category	Tags	Difficulty
Futago	Crypto, CSC	RSA	★
RNG++	Crypto	LCG	★★
babyRSA	Crypto	RSA, ECC	★★
Top Secret	Crypto	GF, dlog	★★☆
Cipher Switching Service	Crypto	RSA, ElGamal	★★☆
Signature	Crypto	ECDSA, LLL, AES-CTR	★★★
RNG+++	Crypto	LCG, LLL	★★★☆
Nim Notes	Web	Script Gadgets, CSRF, CRLF Injection, CSP	★★★☆
Genie [1]	Web, Crypto	Path traversal, AES-CBC, Deserialization	★★★☆
Just a pyjail	Misc	Pyjail	★★★

[1]: This challenge is made by both @splitline and me.

HITCON CTF 2022

Name	Category	Tags	Difficulty
BabySSS	Crypto	SSS, CRT	★☆
Superprime	Crypto	Binary Search, Prune and Search	★★☆
Chimera	Crypto	ECM, LLL/Coppersmith, ECDLP, Hidden Subset Sum	★★★★
LemMinX	Misc	LSP, XXE	★★★
Secure Paste	Web, Crypto	JSONP, Cipher Suite Confusion, DOMPurify, CSP	★★★★

HITCON CTF 2023

Name	Category	Tags	Difficulty
Share	Crypto	SSS, CRT	★★
EZRSA	Crypto	ECC, Wiener, ECM	★★☆
Echo	Crypto	RSA, Index Calculus, LLL	★★★
Random Shuffling Algorithm	Crypto	Noisy CRT, Coppersmith	★★★☆
Collision	Crypto	Code Review, Python Hash Collision	★★★☆
Lisp.js	Misc	Node.js Jail	★★★
Login System	Web	TE.TE, JSON Injection, YAML	★★★
Canvas	Web	JS Jail, Worker, CSP	★★★☆
Harmony	Web	Electron	★★★★☆

ImaginaryCTF 2023

Name	Category	Tags	Difficulty
Tan	Crypto	LLL	★★
Wasteful	Crypto	RSA, Coppersmith	★★
Sus	Crypto	RSA, Math	★★☆
Imaginary Casino	Crypto	CSIDH, RNG	★★☆
Login	Web	PHP	★☆
Sanitized	Web	DOMPurify, XHTML	★★★
Sanitized Revenge	Web	DOMPurify, XHTML	★★★
Typechecker	Reverse	TypeScript, Math	★★
Get and set	Misc	Pyjail	★★

ImaginaryCTF

Name	Category	Tags	Difficulty
Really Simple Algorithm	Crypto	RSA, Continued Fractions	★★
Minimal	Pwn	Stack pivoting, read(2) return value, SROP	★★

These two challenges are created before I became a board of ImaginaryCTF.

Round 26

Name	Category	Tags	Difficulty
Box	Crypto	Affine function	☆
pqqp	Crypto	RSA, Number Theory	★
First RSA	Crypto	RSA	★☆
No modulus	Crypto	RSA, LLL	★★★
Login Please	Web	JavaScript, Prototype	★
Read	Pwn	Shellcoding	★☆
Not a kernel pwn	Misc	Privilege Escalation	★☆
Free Shell	Misc	Bash	★★
Here's some Rev v2	Reverse	Pyc	☆
Here's some Rev v3	Reverse	LCG	★

Round 27

Name	Category	Tags	Difficulty
RSA-CBC	Crypto	RSA	☆
RSA-CBC v2	Crypto	RSA, Coppersmith	★☆
Mobius	Crypto	Rational Function, LLL	★★☆
Hello World as a Service	Misc	Java, Quirks	★☆
Baby Shell	Pwn	C++, std::string_view, UAF	★

Round 28

Name	Category	Tags	Difficulty
Substitution	Crypto	RSA, Search	★☆
Unchanged	Reverse	pthread, LCG	★☆
Filter Master	Web	PHP, filter	★★
Half FFT	Misc	FFT, LLL	★★☆

Round 29

Name	Category	Tags	Difficulty
Strong Prime	Crypto	DLP, CRT	★☆
Web3	Crypto	Ethereum, ECDLP	★★
Req Bin	Web	Python Format String, Flask	★☆
Generic Flag Checker	Reverse	Signal Handler	★☆
xkcd 835	Pwn	UAF	★★

Round 30

Name	Category	Tags	Difficulty
PowerRSA	Crypto	RSA	★
Easy DSA: LCG	Crypto	ECDSA, LCG, LLL	★★☆
Fake Flags	Web	Trolling	☆
Echo	Web	Request Smuggling	★☆

Round 31

Name	Category	Tags	Difficulty
KVIN	Web/Misc	JavaScript	★★

Round 32

Name	Category	Tags	Difficulty
Poly RSA	Crypto	RSA, GCD	★★
Old School	Web	Bash, CGI	★☆

Round 33

Name	Category	Tags	Difficulty
Vault	Web	XSS, Cache	★★☆

Round 34

Name	Category	Tags	Difficulty
Integrity	Crypto	CRT-RSA, Coppersmith	★☆

Round 35

Name	Category	Tags	Difficulty
Encrypted Command Executor	Crypto	ECB	★

Round 37

Name	Category	Tags	Difficulty
You can't reverse me	Misc/Reverse	Hook	★☆

Round 39

Name	Category	Tags	Difficulty
Safe Pickle	Misc	Pickle	★☆

Round 40

Name	Category	Tags	Difficulty
Leet Universe	Crypto	Math	★★

Round 43

Name	Category	Tags	Difficulty
Three Pieces	Crypto	Math	★☆

Round 44

Name	Category	Tags	Difficulty
Flag Server	Web	HTTP Cookie	★★☆
FLT-1337	Misc	Sage Trivia	☆

AIS3 Pre-exam 2022

Name	Category	Tags	Difficulty
JeetQode	Misc	PPC, JQ	★☆
B64DLE	Misc	AES-CTR, Pickle, Python Format String	★★☆
SC	Crypto	Classic	☆
Fast Cipher	Crypto	Modular Arithmetic	☆
shamiko	Crypto	SHA1 Collision, DSA	★☆
Really Strange orAcle	Crypto	GCD, Binomial Theorem	★☆
pettan	Crypto	RSA Small Message, MT19937, Related Message	★★☆
pekobot	Crypto	Invalid Curve Attack	★★★
Flag Checker	Reverse	ROP, Pickle, Single Prime RSA	★★
Private Browsing	Web	SSRF, Redis, PHP Deserialization	★★
UTF-8 Editor	Pwn	C++, std::vector, OOB, GOT overwrite	★★
SAAS	Pwn	C++, Copy Constructor, UAF	★★☆

AIS3 Pre-exam 2023

Name	Category	Tags	Difficulty
ECC	Crypto	ECC	★
Not Wiener	Crypto	RSA, Coppersmith	★★
Media Server	Misc	Python http, procfs	★★
Gitly	Web	0day	★
Password Generator	Pwn	Math, ROP	★☆

AIS3 EOF 2023 - koh-jeopardy

Name	Category	Tags	Difficulty
Shamiko no fukushuu	Crypto	ECDSA, Hmac collision	★
onelinecrypto	Crypto	RSA, LSB	★
NotLFSR	Crypto	LFSR	★☆
magicRSA	Crypto	RSA	★☆
Neo RSA	Crypto	RSA, coppersmith	★★

AIS3 EOF 2024

Name	Category	Tags	Difficulty
Baby Side Channel Attack	Crypto	SCA, RSA	★
Baby ECDLP	Crypto	Math, ECDLP	★☆
Baby XOR	Crypto	Linear Algebra, LLL	★★★
Internal	Web	Nginx, CRLF Injection	★

Security BSides Ahmedabad CTF 2022

Name	Category	Tags	Difficulty
A complex number	Crypto	LLL	★★★