7Rocky's Blog. Cybersecurity and Maths

CTF

400curves

Elliptic Curve Cryptography. Invalid Curve Attack

CTF

4ES

CrewCTF 2024. AES. Meet-in-the-middle

CTF

5x5 Crypto

Polybius Square

CTF

AbraCryptabra

Truncated LCG. AES. Knapsack. LLL lattice reduction

CTF

aes

ImaginaryCTF 09/08/2022. 50 points. AES. Weak password. Brute force

CTF

AESWCM

Custom encryption using AES and XOR

CTF

AESWCM

HTB UniCTF 2022. Custom encryption using AES and XOR. Bad padding implementation

CTF

AHS512

Custom hash function. Bit operations

CTF

AHS512

Custom hash function. Bit operations

CTF

alphascii clashing

MD5 hash collision with constraints

CTF

Ancient Encodings

Hexadecimal and Base64 encodings

CTF

Android-in-the-middle

Diffie-Hellman. MITM

CTF

Arranged

ECC. Finding curve parameters. Modular arithmetic. ECDLP

CTF

Arranged

HTB CA 2024. ECC. Finding curve parameters. Modular arithmetic. ECDLP

CTF

baby quick maffs

Related messages attack. Modular arithmetic

CTF

Bank-er-smith

RSA. Known bits. Coppersmith method. LLL lattice reduction

CTF

Bank-er-smith

HTB UniCTF 2022. RSA. Known bits. Coppersmith method. LLL lattice reduction

CTF

Base 2 2 the 6

Base64 decoding

CTF

BBGun06

RSA. Forge signature. Regular Expression bypass

CTF

BFD56

CBC Bifid cipher

CTF

Biased Heritage

Schnorr signature. Hidden Number Problem. LLL lattice reduction

CTF

Biased Heritage

HTB CA 2023. Schnorr signature. Hidden Number Problem. LLL lattice reduction

CTF

Big RSA

TeamItaly CTF 2023. RSA. Factorial. Modular arithmetic. Integer division

CTF

binary basis

Multiprime RSA. Find private key

CTF

Blessed

BLS12-381. BLS signatures. Rogue key attack. Zero-knowledge proof. EC-LCG. LLL lattice reduction

CTF

Blind

ECSC 2023. First day. ECDSA. Signature verification. XOR

CTF

Bloom Bloom

AES. Shamir Secret Sharing

CTF

Box

ImaginaryCTF 15/09/2022. 50 points. System of linear equations

CTF

Brainy's Cipher

Brainfuck. RSA with CRT

CTF

brevi moduli

RSA. Factorization

CTF

BruXOR

XOR brute force

CTF

Careless Padding

HITCON CTF Quals 2023. Padding Oracle Attack. Custom padding. Guessing

CTF

Character Encoding

ASCII hexadecimal encoding

CTF

Classic, yet complicated!

Vigenère cipher

CTF

Close Enough

SEETF 2022. RSA. Wrong implementation

CTF

Clutch

Quantum Cryptography. Frame-based Quantum Key Distribution

CTF

Clutch

HTB UniCTF 2024. Quantum Cryptography. Frame-based Quantum Key Distribution

CTF

Colliding Heritage

Schnorr signature. MD5 collision

CTF

Colliding Heritage

HTB CA 2023. Schnorr signature. MD5 collision

CTF

Come on feel the nonce

CTFZone Quals 2023. ECDSA. Biased nonces. Hidden Number Problem. LLL lattice reduction

CTF

Composition

Close primes. RSA and ECC. Finding curve parameters. Elliptic curve over composite modulus

CTF

Converging Visions

ECC. Binary search. Finding curve parameters. Smart’s attack. PRNG

CTF

Converging Visions

HTB CA 2023. ECC. Binary search. Finding curve parameters. Smart’s attack. PRNG

CTF

CryptoConundrum

AES cipher. Frequency analysis. Depth-first search

CTF

cryptoGRAPHy (1, 2, 3)

SekaiCTF 2023. Graph Encryption Scheme

Key leakage. Decryption
Single-Destination Shortest Path. Node degrees
Query recovery. Tree isomorphisms

CTF

DHCPPP

ChaCha20-Poly1305. Nonce reuse. DNS

CTF

Down the Rabinhole

Greatest Common Divisor. Modular arithmetic. PKCS7 padding

CTF

Easy DSA: Elated once

ImaginaryCTF 24/01/2023. 100 points. DSA. LCG. Modular system of equations

CTF

Easy DSA: Lovely Little Lane

ImaginaryCTF 21/01/2023. 125 points. DSA. Hidden Number Problem. LLL lattice reduction

CTF

Easy DSA: The beginning

ImaginaryCTF 06/01/2023. 50 points. DSA. Modular arithmetic

CTF

Ebola Virus

DNA encoding. Substitution cipher. Frequency analysis

CTF

El cifrao del cuñao

HackOn CTF 2024. RSA. Binomial theorem. GCD

CTF

El Reset de 1745

HackOn CTF 2024. RSA. LLL lattice reduction. Coppersmith method. ECC. Finding curve parameters. Curve over a composite modulus

CTF

ElElGamal

Traffic analysis. ElGamal. Modular arithmetic

CTF

Elliptic Labyrinth

ECC. Finding curve parameters. Coppersmith method on a bivariate polynomial

CTF

Elliptic Labyrinth

HTB CA 2023. ECC. Finding curve parameters

CTF

Elliptic Labyrinth Revenge

HTB CA 2023. ECC. Finding curve parameters. Coppersmith method on a bivariate polynomial

CTF

Encryption Master

Base64, hexadecimal and binary decoding

CTF

Enormous

ImaginaryCTF 05/08/2022. 50 points. RSA. Large modulus and short exponent

CTF

eyes

corCTF 2023. Matrix equations. Solution to a system of equations

CTF

Farfour Post Quantom

Securinets Quals 2023. Matrix operations. Modular arithmetic. Shuffling. Solve system of equations

CTF

Fast Carmichael

Miller-Rabin primality test

CTF

Fast Carmichael

Miller-Rabin primality test

CTF

Fibopadcci

Padding Oracle Attack. Custom cipher and padding

CTF

Find Marher's Secret

RC4. FMS attack

CTF

fizzbuzz100

corCTF 2023. RSA decryption oracle

CTF

fizzbuzz101

corCTF 2023. RSA decryption. LSB oracle

CTF

fizzbuzz102

corCTF 2023. RSA decryption. LSB oracle. LCG

CTF

Flippin Bank

AES CBC. Bit Flipping Attack. XOR

CTF

Gonna-Lift-Em-All

Modular arithmetic

CTF

Gonna-Lift-Them-All

Modular arithmetic

CTF

Hash the Filesystem

AES CTR. Inverse function of the Python built-in hash function

CTF

Hextraordinary

XOR cipher

CTF

Hide and seek

ECSC 2023. Third day. ECC. Point arithmetic. Discrete logarithm. Pohlig-Hellman

CTF

Homomurphy's Law

Homomorphic encryption. XOR cipher. AES cipher. Brute force

CTF

How The Columns Have Turned

Reverse encryption algorithm

CTF

hybrid unifier

E2E encryption. Diffie-Hellman. AES

CTF

HyperStream Test #2

Bacon Cipher

CTF

I know Mag1k

DES. Padding Oracle Attack

CTF

I'm gRoot

Merkle Tree. Second preimage attack

CTF

Iced Tea

TEA. Reverse encryption function

CTF

Iced TEA

HTB CA 2024. TEA. Reverse encryption function

CTF

Infinite Descent

RSA. Close primes. PRNG

CTF

Infinite Knapsack

Knapsack. Brute force. Modular arithmetic. Shuffling. LLL lattice reduction

CTF

Initialization

AES CTR. Stream cipher. XOR

CTF

Inside The Matrix

Matrix operations. Chinese Remainder Theorem

CTF

Inside The Matrix

HTB CA 2023. Matrix operations. Chinese Remainder Theorem

CTF

Interception

RSA. GCD. Coppersmith method. Euler’s Theorem

CTF

Irish Flan

ECSC 2023. First day. Quaternions. Matrix equations. Kernel

CTF

Jenny From The Block

Block cipher. Known plaintext attack. Induction. SHA256

CTF

Jorge Wants a Token

HackOn CTF 2024. JWT. ECDSA biased nonces. Hidden Number Problem. LLL lattice reduction. Discrete logarithm

CTF

Kernel searcher

ECSC 2023. Third day. Isogeny. Finding curve parameters. Discrete logarithm

CTF

Living with Elegance

Learning With Errors. Probabilistic oracle

CTF

Lost Modulus

RSA. Cube Root Attack

CTF

Lucky Number

Hack.lu CTF 2023. Mersenne primes. Sum of divisors

CTF

LunaCrypt

Binary operations. Simplify and reverse encryption algorithm

CTF

Mayday Mayday

RSA-CRT. Modular arithmetic. Coppersmith method

CTF

Mayday Mayday

HTB UniCTF 2023. RSA-CRT. Modular arithmetic. Coppersmith method

CTF

Mind In The Clouds

ECDSA. Partially-known nonces. LLL lattice reduction

CTF

Mind your Ps and Qs

picoCTF 2021. 20 points. Factorization. RSA decryption

CTF

Mod 26

picoCTF 2021. 10 points. Substitution cipher. ROT13

CTF

Model E1337 - Rolling Code Lock

Advanced web pentesting and cryptanalysis. XXE. Reverse Engineering

CTF

Model E1337 v2 - Hardened Rolling Code Lock

Advanced cryptanalysis. Reverse Engineering

CTF

Morse Code

Decoding a message in Morse code

CTF

MSS

Mignotte Secret Sharing. Modular arithmetic. Chinese Remainder Theorem

CTF

MSS

HTB UniCTF 2023. Mignotte Secret Sharing

CTF

MSS Revenge

HTB UniCTF 2023. Mignotte Secret Sharing. Modular arithmetic. Chinese Remainder Theorem

CTF

Multipage Recyclings

AES cipher. XOR properties

CTF

Multipage Recyclings

HTB CA 2023. AES cipher. XOR properties

CTF

Noisy CRC

SekaiCTF 2023. CRC. Chinese Remainder Theorem. Brute force

CTF

not crypto

ECSC 2023. Third day. ROT13. Base64 encoding. ASCII bytes

CTF

Not that random

HMAC. Hash functions

CTF

Nuclear Sale

PCAP analysis. XOR cipher

CTF

One Step Closer

Franklin-Reiter related-message attack

CTF

Optimus Prime

RSA. Greatest Common Divisor

CTF

Oracle Leaks

RSA. Manger’s attack

CTF

Paranormial Commitment Scheme

Plaid CTF 2024. BLS12-381. Elliptic curve pairings. Lagrange interpolation

CTF

Partial Tenacity

RSA. Partially-known private information. Modular arithmetic

CTF

Partial Tenacity

HTB CA 2024. RSA. Partially-known private information. Modular arithmetic

CTF

Pederson

HackOn CTF 2025. Zero-knowledge proof. Pedersen commitment

CTF

Perfect Synchronization

AES cipher. Frequency analysis

CTF

Personalized

ImaginaryCTF 07/08/2022. 75 points. RSA. PRNG seed. CRT

CTF

plai_n_rsa

SECCON CTF Quals 2023. RSA. Euler totient function

CTF

Play Time

HackOn CTF 2025. Modular arithmetic. Xoshiro256**. LFSR. z3 solver

CTF

PolyLCG

Securinets Quals 2023. Modular polynomials

CTF

pqqp

ImaginaryCTF 07/09/2022. 75 points. RSA. Fermat’s Little Theorem

CTF

Prime

Balsn CTF 2023. AKS primality test. Carmichael numbers. Euler totient function

CTF

Protein Cookies 2

Hash length extension attack. Custom hash function

CTF

Put a ring on it

ECSC 2023. Third day. Ring signature. Oracle

CTF

qcg-k

corCTF 2023. DSA. Recurrence relation. Nonces

CTF

Quadratic Leak

m0leCon CTF 2025 Teaser. RSA. Modular arithmetic. Polynomial

CTF

Quadratic Points

Integer linear relations. LLL lattice reduction. ECDLP. CRT

CTF

Rather Secure Attachment

ImaginaryCTF 08/12/2022. 100 points. RSA. Cipolla’s Algorithm

CTF

read before you sign

JWT. ECDSA. Java psychic signatures

CTF

Read between the lines

CrewCTF 2024. RSA. Integer linear relations. LLL lattice reduction

CTF

Relatively Small Arguments

ImaginaryCTF 14/07/2022. 75 points. RSA. Wiener’s attack

CTF

Reverse Polarity

Decoding ASCII binary

CTF

Right Decision

CTFZone Quals 2023. Shamir Secret Sharing. System of equations

CTF

RLotto

PRNG. Time-based seed

CTF

Rolled my own Crypto

ImaginaryCTF 04/09/2022. 90 points. DSA. Abusing special values

CTF

Ron was wrong, Whit is right

ImaginaryCTF 28/11/2022. 75 points. RSA. Greatest Common Divisor. Bad PRNG

CTF

Rookie Mistake

RSA. Modular square root. Smooth primes. Discrete logarithm

CTF

Rotating Secret Assembler

ImaginaryCTF 05/07/2022. 50 points. RSA. Greatest Common Divisor

CTF

Roulette

PRNG. Custom Mersenne Twister. System of equations with binary variables

CTF

rps-casino

DiceCTF 2024 Quals. LFSR. Modular arithmetic. z3

CTF

RRSSAA

ECSC 2023. Third day. Multi-prime RSA. PRNG seed. RSA-CRT decryption

CTF

RSA 4.0

SECCON CTF Quals 2023. RSA. Quaternions. GCD

CTF

RSA Beginner

RSA. Factorization attack

CTF

RSA Noob

RSA. Wrong implementation

CTF

RSACBC

HackOn CTF 2025. RSA. XOR. Binomial theorem. GCD

CTF

RsaCtfTool

RSA. Euler’s totient function. AES decryption

CTF

RSAgain

ImaginaryCTF 20/11/2022. 90 points. RSA. Common modulus attack

CTF

same

ImaginaryCTF 10/08/2022. 75 points. RSA. Common modulus attack

CTF

Scrambled Pizzeria

TeamItaly CTF 2023. XOR. Permutations and substitutions

CTF

Secure Signing

Hash function. XOR. Oracle

CTF

secure source

JWT. ECDSA. Python random state

CTF

sekur julius

Caesar cipher

CTF

HITCON CTF Quals 2023. Shamir Secret Sharing. Lagrange interpolation. Chinese Remainder Theorem. multiprocessing

CTF

Signing Factory

Modular arithmetic. RSA signature. Malleability

CTF

signup

DSA. Nonce reuse. Modular arithmetic

CTF

Small StEps

HTB CA 2023. RSA. Cube Root Attack

CTF

So many 64s

Multiple Base64 encoding

CTF

Space Pirates

Shamir Secret Sharing. PRNG seed

CTF

SPG

Boolean oracle

CTF

Spooky RSA

RSA. Greatest Common Divisor

CTF

Spooky RSA

RSA. Greatest Common Divisor

CTF

Spooky Safebox

Hack.lu CTF 2023. ECC. ECDSA. Public key recovery. Biased nonces. Hidden Number Problem. LLL lattice reduction

CTF

Substitution Cipher

Guessing substitution cipher

CTF

sugar free candies

Solution to a non-linear system of equations

CTF

Sum-O-Primes

picoCTF 2022. 400 points. RSA decryption

CTF

Symbols

Quadratic residues. Legendre Symbol

CTF

Tapping

picoCTF 2019. 200 points. Morse code

CTF

The Three-Eyed Oracle

AES ECB oracle

CTF

Tough decisions

ECSC 2023. First day. Learning With Errors. Modular arithmetic

CTF

Tsayaki

TEA. Equivalent keys. CBC mode

CTF

Tsayaki

HTB CA 2024. TEA. Equivalent keys. CBC mode

CTF

TurboCipher

Recurrence relation. Telescoping series. LCG

CTF

Twist and shout

ECSC 2023. Third day. ECC. Invalid Curve Attack. Quadratic Twist

CTF

two-wrongs

corCTF 2024. Quantum Computing. Quantum Error Correction

CTF

TwoForOne

RSA. Common modulus attack

CTF

Ursa Minor

Black Hat MEA CTF 2022. RSA. Binary Search. Smooth primes

CTF

Vigenère Cipher

Vigenère decryption

CTF

Vitrium Stash

DSA. Modular arithmetic. LLL lattice reduction

CTF

Waiting List

ECDSA. Nonces with known bits. Hidden Number Problem. LLL lattice reduction

CTF

Weak RSA

RSA. Wiener’s attack

CTF

Whole Lotta Candy

AES cipher modes. Stream cipher. Known plaintext attack

CTF

Whole Lotta Candy

AES cipher modes. Stream cipher. Known plaintext attack

CTF

winter

DiceCTF 2024 Quals. Winternitz One-Time Signature

CTF

WOTS Up

ECSC 2023. First day. Winternitz One-Time Signature. Hash functions. Induction

CTF

WOTS Up 2

ECSC 2023. First day. Winternitz One-Time Signature. Hash functions

CTF

XORed

ImaginaryCTF 02/09/2022. 50 points. XOR cipher

CTF

yaonet

DiceCTF 2024 Quals. ECC. Baby-step, giant-step. Meet-in-the-middle

CTF

Zombie Rolled

Fractions. Diophantine equation solution with elliptic curve. RSA signature. LLL lattice reduction. Groebner basis

CTF

Zombie Rolled

HTB UniCTF 2023. Fractions. GCD. RSA signature. Coppersmith method on bivariate polynomial

CTF

はやぶさ

SekaiCTF 2024. Falcon. Lattice attack on NTRU. BKZ. Key recovery attack

CTF

マスタースパーク

SekaiCTF 2024. Isogeny-based cryptography. CSIDH. Discrete logarithm. CRT