Hack The Box Challenges (Crypto)

Modular arithmetic. RSA signature. Malleability

Solution to a non-linear system of equations

Caesar cipher

Multiprime RSA. Find private key

RSA. Factorization

MD5 hash collision with constraints

Quantum Cryptography. Frame-based Quantum Key Distribution

Hash function. XOR. Oracle

Hash length extension attack. Custom hash function

AES. Shamir Secret Sharing

HMAC. Hash functions

Integer linear relations. LLL lattice reduction. ECDLP. CRT

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

Learning With Errors. Probabilistic oracle

RSA. Cube Root Attack

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

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

Merkle Tree. Second preimage attack

Quadratic residues. Legendre Symbol

Boolean oracle

TEA. Equivalent keys. CBC mode

ECC. Finding curve parameters. Modular arithmetic. ECDLP

RSA. Partially-known private information. Modular arithmetic

TEA. Reverse encryption function

RSA. Modular square root. Smooth primes. Discrete logarithm

DSA. Modular arithmetic. LLL lattice reduction

RSA. GCD. Coppersmith method. Euler’s Theorem

PRNG. Time-based seed

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

RSA-CRT. Modular arithmetic. Coppersmith method

Mignotte Secret Sharing. Modular arithmetic. Chinese Remainder Theorem

AES CTR. Stream cipher. XOR

AES CBC. Bit Flipping Attack. XOR

Recurrence relation. Telescoping series. LCG

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

AES cipher. Frequency analysis. Depth-first search

CBC Bifid cipher

AES cipher. Frequency analysis

Hexadecimal and Base64 encodings

Padding Oracle Attack. Custom cipher and padding

DES. Padding Oracle Attack

Homomorphic encryption. XOR cipher. AES cipher. Brute force

DSA. Nonce reuse. Modular arithmetic

Related messages attack. Modular arithmetic

RSA. Manger’s attack

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

Schnorr signature. Hidden Number Problem. LLL lattice reduction

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

Schnorr signature. MD5 collision

Matrix operations. Chinese Remainder Theorem

AES cipher. XOR properties

RSA. Common modulus attack

Binary operations. Simplify and reverse encryption algorithm

Elliptic Curve Cryptography. Invalid Curve Attack

RSA. Euler’s totient function. AES decryption

PCAP analysis. XOR cipher

RSA. Greatest Common Divisor

Truncated LCG. AES. Knapsack. LLL lattice reduction

DNA encoding. Substitution cipher. Frequency analysis

Traffic analysis. ElGamal. Modular arithmetic

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

Custom encryption using AES and XOR

RSA. Known bits. Coppersmith method. LLL lattice reduction

Custom hash function. Bit operations

AES cipher modes. Stream cipher. Known plaintext attack

RSA. Greatest Common Divisor

Miller-Rabin primality test

Modular arithmetic

RC4. FMS attack

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

RSA. Forge signature. Regular Expression bypass

Brainfuck. RSA with CRT

AES ECB oracle

Shamir Secret Sharing. PRNG seed

RSA. Close primes. PRNG

Franklin-Reiter related-message attack

Vigenère cipher

Block cipher. Known plaintext attack. Induction. SHA256

Diffie-Hellman. MITM

RSA. Wiener’s attack

Greatest Common Divisor. Modular arithmetic. PKCS7 padding

Reverse encryption algorithm