write-up - :smirk_cat: CTF write-ups

项目说明

CTF write-ups

CTF write-ups written by me. Mostly crypto and blockchain!

2023

TSG CTF 2023

- Crypto 341 - Delta Force - Writeup
- DLP o curve o ring: Reduction to additi / Pohlig Hellman

CCE 2023

- Crypto 451 - NZK-SIARK - Writeup
- AES intermdiate state forgery
- Crypto 451 - De-Identification - Writeup
- Format Preserving encryption

DiceCTF 2023

- Crypto 199 - BBBB - Writeup
- LCG parameter selection to make RNG cyclic + Coppersmith Attack

2022

CODEGATE 2022 Final

- Blockchain 500 - Look It Up - Writeup-EN, Writeup-KR
- Plonkup + frozen heart + Solidity Optimizer Keccak Caching Bug

RCTF 2022

- Crypto 769 - S2DH - Writeup
- Cracking SIDH using Castryck-Decru Attack
- Crypto 645 - IS_THIS_LCG? - Writeup
- Truncated LCG + EC-LCG with only 7 x-coordinate + Matrix LCG

LakeCTF 2022

- Crypto 416 - NeutronMail - Writeup
- Decrypting PGP message with not so random public PGP keys, factoring with gcd.
- Blockchain 372 - Immutable - Writeup
- Update code of a deployed contract using CREATE, CREATE2, and SELFDESTRUCT
- Blockchain 388 - QuinEVM - Writeup
- Shortest E

angstromCTF 2022

- Crypto 110 - logloglog - Writeup
- Pohlig Hellman Algorithm for groups of prime-power order.

Plaid CTF 2022

- Crypto 400 - choreography - Writeup
- Complementation Slide + Twisted Slide Attack on generalized Feistel Structure.

LINE CTF 2022

- Crypto 138 - Baby crypto re - Writeup
- Reduction to ECDSA biased nonce atack.

zer0pts CTF 2022

- Crypto 304 - Karen - Writeup
- Solving Hidden Subset Sum Problem with Nguyen-Stern algorithm.

2021

POC Cutting Edge CTF 2021

- Crypto 994 - vpoly - Writeup
- Solving discrete logarithm problem o field.

InCTF 2021

- Crypto 925 - Trouble With Pairs - Writeup
- BLS Signature Forgery.
- Re 100 - find_plut0 - Writeup
- Simple re using z3.

2020

KAPO 2020

- Crypto 100 - fixed point revenge - Writeup
- Affine structure of crc.
- Crypto 100 - Baby Bubmi - Writeup
- Extension of knapsack cipher.
- Crypto 100 - Child Beubmi - Writeup
- Coppersmith attack on multiprime RSA.

Crypto CTF 2020

- Crypto 316 - Fatima - Writeup
- Solve tiny ECDLP and write inverse functions.
- Crypto 285 - Complex to Hell - Writeup
- Brute key matrix using flag oracle.
- Crypto 142 - One Line Crypto - Writeup
- Weak prime generation logic for textbook RSA.
- Crypto 95 - Gambler - Writeup
- Sol equation o ring.
- Crypto 90 - Three Ravens - Writeup
- Small message with single factor leak.
- Crypto 55 - Amsterdam - Writeup
- Binomial coefficient based encoding.
- Crypto 29 - Trailing Bits - Writeup
- Trucated plaintext.

Defenit CTF 2020

- Crypto 201 - Double Message - Writeup
- Coppersmith's short pad attack + Franklin-Reiter related message attack.
- Misc 906 - Dodge - Writeup
- Automated dodge solver.
- Misc 298 - Minesweeper - Writeup
- Automated minesweeper solver.
- Misc 181 - QR Generator - Writeup
- QRCode repl.

Pwn2Win CTF 2020

- Crypto 246 - Omni Crypto - Writeup
- Coppersmith's attack on partial p exposure on RSA.
- Crypto 115 - Androids Encryption - Writeup
- Leak AES key on PCBC.

DEF CON CTF Qualifier 2020

- Crypto 130 - coooppersmith - Writeup
- Factor n using bi coppersmith with leaked info.
- Re 120 - ooobash - Writeup
- Bash shell re.

PlaidCTF 2020

- Crypto 350 - MPKC - Writeup
- Destroy multi quadratic polynomial based encyption scheme by linear algebra.
- Crypto 250 - dyrpto - Writeup
- Coppersmith's short pad attack + Franklin-Reiter related message attack.

TAMUctf 2020

- Crypto 338 - ETERNAL_GAME - Writeup
- Hash length extension attack.
- Web 262 - MENTALMATH - Writeup
- Ajax code injection.
- Web 122 - FILESTORAGE - Writeup
- LFI + php session poisoning.
- Web 50 - PASSWORD_EXTRACTION - Writeup
- Blind SQL injection.
- Misc 50 - INSTAGRAM - Writeup
- JPEG marker recovery.
- Misc 50 - BLIND - Writeup
- Reverse shell.

zer0pts CTF 2020

- Crypto 636 - dirty laundry - Writeup
- Paillier cryptosystem with Shamir's secret sharing.
- Crypto 394 - diysig - Writeup
- RSA with LSB oracle.
- Crypto 260 - ROR - Writeup
- Concat LSB for gaining ciphertext
- Forensics 100 - Locked KitKat - Writeup
- Bruteforce android pattern lock

Pragyan CTF 2020

- Crypto 150 - AskTheOracle - Writeup
- Oracle Padding Attack.

nullcon HackIM 2020

- Crypto 419 - SecureLinearFunctionE - Writeup
- Break Bellare-Micali OT by simple math.

WhiteHat Grand Pix 06 Quals

- Crypto 200 - Cryptography 01 - Writeup
- Simple substitution cipher.

2019

Christmas CTF 2019

- Crypto 1000 - hide and seek - Writeup
- Solving hidden number problem + Coppersmith's attack on partial p exposure on RSA.
- Crypto 995 - christmas pockets - Writeup
- Classical knapsack cryptosystem is to low density attack.

HITCON CTF 2019 Quals

- Crypto 200 - Lost Modulus Again - Writeup
- Recover n to decrypt the flag since d is given.
- Crypto 200 - Very Simple Haskell - Writeup
- Decrypt Naccache-Stern Knapsack problem by directly knowing the private key.

KAPO 2019

- Crypto 1 - Lenstra-Lenstra-Lovasz - Writeup
- Recover dp by using Coppersmith's attack, and recover p.
- Crypto 1 - Weak-Strong - Writeup
- ROCA attack.

CSAW CTF Qualification Round 2019

- Crypto 400 - Fault Box - Writeup
- Fault attack on RSA CRT with a slight twist.
- Crypto 300 - SuperCurve - Writeup
- Solving ECDLP when order is small.
- Crypto 100 - count on me - Writeup
- Misdesigned block cipher leads to information leakage.

Affinity CTF 2019 Quals

- Crypto 500 - Epic Poem - Writeup
- XOR encryption, guessing based on flag format.
- Crypto 350 - GolanG Heights - Writeup
- Sol equation to factor n on RSA.

HackCon 2019

- Crypto 467 - AgainAndAgainAndAgain - Writeup
- Multiple encryption with Rabin cryptosystem.

Crypto CTF 2019

- Crypto 314 - NSA basement - Writeup
- Factoring n using gcd, decryption with OAEP on multiprime condition.
- Crypto 166 - Alone in the dark - Writeup
- Solving pellian equation.

ISITDTU CTF 2019 Quals

- Crypto 304 - Chaos - Writeup
- Simple substitution cipher.
- Crypto 100 - Easy RSA 1 - Writeup
- n and e ha size, so apply Boneh-Durfee attack.
- Crypto 919 - Easy RSA 2 - Writeup
- Crack multiprime RSA with Fermat factorization.
- Crypto 238 - Old Story - Writeup
- Base64 encoding with guessing.
- Crypto 395 - decrypt to me - Writeup
- Weak prng.

Facebook CTF 2019

- Crypto 974 - netscream - Writeup
- Dual_EC_DRBG with some re.
- Crypto 919 - storagespace - Writeup
- Order of curve is small, use sage's discrete_log() function.

DEF CON CTF Qualifier 2019

- Crypto 182 - tania - Writeup
- DSA with LCG nonces are broken using LLL, or apply biased nonce attack.

Harekaze CTF 2019

- Crypto 200 - Now We Can Play!! - Writeup
- Simple bruteforcing problem.
- Crypto 100 - ONCE UPON A TIME - Writeup
- Hill cipher with randomness and padding.
- Crypto 200 - Show me your private key - Writeup
- Order of elliptic cur over Zmod(n), where n is composite.

2018

KAPO 2018

- Re 50 - hdbt - Writeup
- Calculating inverse o field.
- Re 50 - ezbt - Writeup
- Consecutive XOR for in.

项目信息

开发语言：Sage

Star 数：221

技术要点

该项目属于CTF思路方向的开源资源，代码结构清晰，适合安全研究人员学习参考。项目围绕:smirk_cat: CTF write-ups展开，提供了可运行的实现，对理解相关安全机制、工具原理与攻防技术具有较高的研究价值。

从技术实现角度看，此类项目的核心在于对底层原理的深入理解与工程化落地。开发者在研究过程中可以结合官方文档与社区讨论，梳理项目的初始化流程、核心模块职责与数据流转，逐步掌握其中的技术细节与设计思路。

使用与学习建议

1. 下载源码压缩包，解压到本地环境。

2. 根据项目类型准备对应的运行环境与依赖。

3. 按照 README 中的步骤完成配置与部署。

4. 在隔离的测试环境中运行验证，避免影响生产系统。

免责声明

本资源来源于开源社区，仅供安全研究、技术学习与合法授权范围内的攻防演练使用，请勿用于任何非法或侵害他人权益的用途。使用本项目产生的一切后果由使用者自行承担。