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https://github.com/pcw109550/write-up

:smirk_cat: CTF write-ups
https://github.com/pcw109550/write-up

cryptography ctf ctf-writeups

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:smirk_cat: CTF write-ups

Host: GitHub
URL: https://github.com/pcw109550/write-up
Owner: pcw109550
Created: 2019-05-15T21:03:53.000Z (over 5 years ago)
Default Branch: master
Last Pushed: 2023-11-05T17:24:34.000Z (about 1 year ago)
Last Synced: 2024-08-05T17:45:26.621Z (4 months ago)
Topics: cryptography, ctf, ctf-writeups
Language: Sage
Homepage:
Size: 50.7 MB
Stars: 192
Watchers: 7
Forks: 26
Open Issues: 2
Metadata Files:
- Readme: README.md

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awesome-hacking-lists - pcw109550/write-up - :smirk_cat: CTF write-ups (Sage)

README

# CTF write-ups

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

## 2023

- **TSG CTF 2023**
- Crypto 341 - Delta Force - [Writeup](https://github.com/pcw109550/write-up/tree/master/2023/TSG/Delta-Force)
- DLP over singular curve over composite ring: Reduction to additive Group / Pohlig Hellman
- **CCE 2023**
- Crypto 451 - NZK-SIARK - [Writeup](https://github.com/pcw109550/write-up/tree/master/2023/CCE/NZK-SIARK)
- AES intermdiate state forgery
- Crypto 451 - De-Identification - [Writeup](https://github.com/pcw109550/write-up/tree/master/2023/CCE/De-Identification)
- Format Preserving encryption
- **DiceCTF 2023**
- Crypto 199 - BBBB - [Writeup](https://github.com/pcw109550/write-up/tree/master/2023/Dice/BBBB)
- LCG parameter selection to make RNG cyclic + Coppersmith Attack

## 2022

- **CODEGATE 2022 Final**
- Blockchain 500 - Look It Up - [Writeup-EN](https://github.com/pcw109550/write-up/tree/master/2022/CODEGATE/Final/Look_It_Up/README.md), [Writeup-KR](https://github.com/pcw109550/write-up/tree/master/2022/CODEGATE/Final/Look_It_Up/README_KR.md)
- Plonkup + frozen heart vulnerability + Solidity Optimizer Keccak Caching Bug
- **RCTF 2022**
- Crypto 769 - S2DH - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/RCTF/S2DH)
- Cracking SIDH using Castryck-Decru Attack
- Crypto 645 - IS_THIS_LCG? - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/RCTF/IS_THIS_LCG)
- Truncated LCG + EC-LCG with only 7 x-coordinate + Matrix LCG
- **LakeCTF 2022**
- Crypto 416 - NeutronMail - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/Lake/NeutronMail)
- Decrypting PGP message with not so random public PGP keys, factoring with gcd.
- Blockchain 372 - Immutable - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/Lake/Immutable)
- Update code of a deployed contract using `CREATE`, `CREATE2`, and `SELFDESTRUCT`
- Blockchain 388 - QuinEVM - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/Lake/QuinEVM)
- Shortest EVM quine
- **angstromCTF 2022**
- Crypto 110 - logloglog - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/angstromCTF/logloglog)
- Pohlig Hellman Algorithm for groups of prime-power order.
- **Plaid CTF 2022**
- Crypto 400 - choreography - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/PlaidCTF/choreography)
- Complementation Slide + Twisted Slide Attack on generalized Feistel Structure.
- **LINE CTF 2022**
- Crypto 138 - Baby crypto revisited - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/LINE/Baby_crypto_revisited)
- Reduction to ECDSA biased nonce atack.
- **zer0pts CTF 2022**
- Crypto 304 - Karen - [Writeup](https://github.com/pcw109550/write-up/tree/master/2022/zer0pts/Karen)
- Solving Hidden Subset Sum Problem with Nguyen-Stern algorithm.

## 2021

- **POC Cutting Edge CTF 2021**
- Crypto 994 - vpoly - [Writeup](https://github.com/pcw109550/write-up/tree/master/2021/POC_Cutting_Edge_CTF/vpoly)
- Solving discrete logarithm problem over finite field.
- **InCTF 2021**
- Crypto 925 - Trouble With Pairs - [Writeup](https://github.com/pcw109550/write-up/tree/master/2021/InCTF/Trouble_With_Pairs)
- BLS Signature Forgery.
- Reversing 100 - find_plut0 - [Writeup](https://github.com/pcw109550/write-up/tree/master/2021/InCTF/find_plut0)
- Simple reversing using z3.

## 2020

- **KAPO 2020**
- Crypto 100 - fixed point revenge - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/KAPO/fixed_point_revenge)
- Affine structure of crc.
- Crypto 100 - Baby Bubmi - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/KAPO/Baby_Bubmi)
- Extension of knapsack cipher.
- Crypto 100 - Child Beubmi - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/KAPO/Child_Beubmi)
- Coppersmith attack on multiprime RSA.
- **Crypto CTF 2020**
- Crypto 316 - Fatima - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/CryptoCTF/Fatima)
- Solve tiny ECDLP and write inverse functions.
- Crypto 285 - Complex to Hell - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/CryptoCTF/Complex_to_Hell)
- Brute key matrix using flag oracle.
- Crypto 142 - One Line Crypto - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/CryptoCTF/One_Line_Crypto)
- Weak prime generation logic for textbook RSA.
- Crypto 95 - Gambler - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/CryptoCTF/Gambler)
- Solve cubic equation over polynomial ring.
- Crypto 90 - Three Ravens - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/CryptoCTF/Three_Ravens)
- Small message with single factor leak.
- Crypto 55 - Amsterdam - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/CryptoCTF/Amsterdam)
- Binomial coefficient based encoding.
- Crypto 29 - Trailing Bits - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/CryptoCTF/Trailing_Bits)
- Trucated plaintext.
- **Defenit CTF 2020**
- Crypto 201 - Double Message - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/Defenit/Double_Message)
- Coppersmith's short pad attack + Franklin-Reiter related message attack.
- Misc 906 - Dodge - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/Defenit/Dodge)
- Automated [dodge](https://editown.tistory.com/101) solver.
- Misc 298 - Minesweeper - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/Defenit/Minesweeper)
- Automated minesweeper solver.
- Misc 181 - QR Generator - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/Defenit/QR_Generator)
- QRCode repl.
- **Pwn2Win CTF 2020**
- Crypto 246 - Omni Crypto - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/Pwn2Win/Omni_Crypto)
- Coppersmith's attack on partial `p` exposure on RSA.
- Crypto 115 - Androids Encryption - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/Pwn2Win/Androids_Encryption)
- Leak AES key on PCBC.
- **DEF CON CTF Qualifier 2020**
- Crypto 130 - coooppersmith - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/DEFCON/coooppersmith)
- Factor `n` using bivariate coppersmith with leaked info.
- Reversing 120 - ooobash - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/DEFCON/ooobash)
- Bash shell reversing.
- **PlaidCTF 2020**
- Crypto 350 - MPKC - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/PlaidCTF/MPKC)
- Destroy multivariate quadratic polynomial based encyption scheme by linear algebra.
- Crypto 250 - dyrpto - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/PlaidCTF/dyrpto)
- Coppersmith's short pad attack + Franklin-Reiter related message attack.
- **TAMUctf 2020**
- Crypto 338 - ETERNAL_GAME - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/TAMUctf/ETERNAL_GAME)
- Hash length extension attack.
- Web 262 - MENTALMATH - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/TAMUctf/MENTALMATH)
- Ajax code injection.
- Web 122 - FILESTORAGE - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/TAMUctf/FILESTORAGE)
- LFI + php session poisoning.
- Web 50 - PASSWORD_EXTRACTION - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/TAMUctf/PASSWORD_EXTRACTION)
- Blind SQL injection.
- Misc 50 - INSTAGRAM - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/TAMUctf/INSTAGRAM)
- JPEG marker recovery.
- Misc 50 - BLIND - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/TAMUctf/BLIND)
- Reverse shell.
- **zer0pts CTF 2020**
- Crypto 636 - dirty laundry - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/zer0pts/dirty_laundry)
- Paillier cryptosystem with Shamir's secret sharing.
- Crypto 394 - diysig - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/zer0pts/diysig)
- RSA with LSB oracle.
- Crypto 260 - ROR - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/zer0pts/ROR)
- Concat LSB for gaining ciphertext
- Forensics 100 - Locked KitKat - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/zer0pts/Locked_KitKat)
- Bruteforce android pattern lock
- **Pragyan CTF 2020**
- Crypto 150 - AskTheOracle - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/Pragyan/AskTheOracle)
- Oracle Padding Attack.
- **nullcon HackIM 2020**
- Crypto 419 - SecureLinearFunctionEvaluation - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/HackIM/SecureLinearFunctionEvaluation)
- Break Bellare-Micali OT by simple math.
- **WhiteHat Grand Pix 06 Quals**
- Crypto 200 - Cryptography 01 - [Writeup](https://github.com/pcw109550/write-up/tree/master/2020/WhiteHat_GrandPrix/Cryptography_01)
- Simple substitution cipher.

## 2019

- **Christmas CTF 2019**
- Crypto 1000 - hide and seek - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/X-MAS/hide_and_seek)
- Solving hidden number problem + Coppersmith's attack on partial `p` exposure on RSA.
- Crypto 995 - christmas pockets - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/X-MAS/christmas_pockets)
- Classical knapsack cryptosystem is vulnerable to low density attack.
- **HITCON CTF 2019 Quals**
- Crypto 200 - Lost Modulus Again - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/HITCON/Lost_Modulus_Again)
- Recover `n` to decrypt the flag since `d` is given.
- Crypto 200 - Very Simple Haskell - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/HITCON/Very_Simple_Haskell)
- Decrypt Naccache-Stern Knapsack problem by directly knowing the private key.
- **KAPO 2019**
- Crypto 1 - Lenstra-Lenstra-Lovasz - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/KAPO/Lenstra-Lenstra-Lovasz)
- Recover `dp` by using Coppersmith's attack, and recover `p`.
- Crypto 1 - Weak-Strong - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/KAPO/Weak-Strong)
- ROCA attack.
- **CSAW CTF Qualification Round 2019**
- Crypto 400 - Fault Box - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/CSAW/Fault_Box)
- Fault attack on RSA CRT with a slight twist.
- Crypto 300 - SuperCurve - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/CSAW/SuperCurve)
- Solving ECDLP when order is small.
- Crypto 100 - count on me - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/CSAW/count_on_me)
- Misdesigned block cipher leads to information leakage.
- **Affinity CTF 2019 Quals**
- Crypto 500 - Epic Poem - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/Affinity/Epic_Poem)
- XOR encryption, guessing based on flag format.
- Crypto 350 - GolanG Heights - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/Affinity/GolanG_Heights)
- Solve quartic equation to factor `n` on RSA.
- **HackCon 2019**
- Crypto 467 - AgainAndAgainAndAgain - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/HackCon/AgainAndAgainAndAgain)
- Multiple encryption with Rabin cryptosystem.
- **Crypto CTF 2019**
- Crypto 314 - NSA basement - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/CryptoCTF/NSA_basement)
- Factoring `n` using gcd, decryption with OAEP on multiprime condition.
- Crypto 166 - Alone in the dark - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/CryptoCTF/Alone_in_the_dark)
- Solving pellian equation.
- **ISITDTU CTF 2019 Quals**
- Crypto 304 - Chaos - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/ISITDTU/Chaos)
- Simple substitution cipher.
- Crypto 100 - Easy RSA 1 - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/ISITDTU/Easy_RSA_1)
- `n` and `e` have similar size, so apply Boneh-Durfee attack.
- Crypto 919 - Easy RSA 2 - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/ISITDTU/Easy_RSA_2)
- Crack multiprime RSA with Fermat factorization.
- Crypto 238 - Old Story - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/ISITDTU/Old_story)
- Base64 encoding with guessing.
- Crypto 395 - decrypt to me - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/ISITDTU/decrypt_to_me)
- Weak prng.
- **Facebook CTF 2019**
- Crypto 974 - netscream - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/Facebook/netscream)
- Dual_EC_DRBG with some reversing.
- Crypto 919 - storagespace - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/Facebook/storagespace)
- Order of curve is small, use sage's `discrete_log()` function.
- **DEF CON CTF Qualifier 2019**
- Crypto 182 - tania - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/DEFCON/tania)
- DSA with LCG nonces are broken using LLL, or apply biased nonce attack.
- **Harekaze CTF 2019**
- Crypto 200 - Now We Can Play!! - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/Harekaze/Now_We_Can_Play)
- Simple bruteforcing problem.
- Crypto 100 - ONCE UPON A TIME - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/Harekaze/ONCE_UPON_A_TIME)
- Hill cipher with randomness and padding.
- Crypto 200 - Show me your private key - [Writeup](https://github.com/pcw109550/write-up/tree/master/2019/Harekaze/show_me_your_private_key)
- Order of elliptic curve defined over `Zmod(n)`, where `n` is composite.

## 2018

- **KAPO 2018**
- Reversing 50 - hdbt - [Writeup](https://github.com/pcw109550/write-up/tree/master/2018/KAPO/hdbt)
- Calculating inverse over finite field.
- Reversing 50 - ezbt - [Writeup](https://github.com/pcw109550/write-up/tree/master/2018/KAPO/ezbt)
- Consecutive XOR for inversion.