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2021 Crypto Writeups |
My first ever cryptography related challenge solve in a CTF was 1n-Jection in Zh3r0 CTF 2021. Since then I have solved many more. Below is a list of writeups for all the cryptography related challenges that I have solved in CTFs in 2021 :
| Challenge | CTF | Category | Solves |
|---|---|---|---|
| Rotting Fruits | idek 2021 | Caesar Cipher | 178/235 |
| Nameless | idek 2021 | RSA, Quadratic Polynomials | 64/235 |
| Hashbrown | idek 2021 | Hashes, Bruteforce | 45/235 |
| Seed of Life | idek 2021 | Random Seeds, Bruteforce | 31/235 |
| Polyphenol | idek 2021 | LLL | 21/235 |
| Destroyed RSA 🩸 | idek 2021 | RSA, Complex Multiplication Factorization, Flawed Exponent | 16/235 |
| EccRoll | idek 2021 | ECC, Quadratic Residues | 14/235 |
| Key Exchange | Buckeye 2021 | Diffie-Hellman | 141/505 |
| Key Exchange 2 | Buckeye 2021 | Diffie-Hellman, Lagrange's Theorem, Small Subgroup | 34/505 |
| Defective RSA | Buckeye 2021 | RSA, Flawed Exponent, Roots of Unity modulo n | 33/505 |
| Elliptigo 🩸 | Buckeye 2021 | ECC, Points of low order | 21/505 |
| Super VDF | Buckeye 2021 | Pollard's p-1 factorization, Euler's Theorem | 15/505 |
| Pseudo | Buckeye 2021 | Miller-Rabin Pseudoprimes, Legendre Symbol | 15/505 |
| Alkaloid Stream | Perfect Blue 2021 | Custom Scheme | 132/210 |
| Steroid Stream | Perfect Blue 2021 | Custom Scheme, Linear Dependence & Independence | 38/210 |
| GoodHash | Perfect Blue 2021 | AES-GCM, GHASH, Ciphertext Collisions | 30/210 |
| RSA Pop Quiz | CSAW Quals 2021 | Wiener's Attack, RSA LSB Oracle, Coppersmith | 137/1216 |
| Forgery | CSAW Quals 2021 | ElGamal Signature, Existential Forgery | 127/1216 |
| ECC Pop Quiz | CSAW Quals 2021 | ECC, Smart's Attack, MOV Attack, Singular Curve Attack | 63/1216 |
| Bits | CSAW Quals 2021 | Discrete Log Oracle, Bit Propagation | 24/1216 |
| Sharing Secrets | Yauza CTF 2021 | CRT | 50/227 |
| Knapsack | Yauza CTF 2021 | Hellman-Knapsack | 35/227 |
| Signature | Yauza CTF 2021 | Custom Signature Scheme | 31/227 |
| Leaky Blinders | Fword CTF 2021 | N/A | 120/428 |
| Boombastic | Fword CTF 2021 | Gröbner basis | 54/428 |
| Invincible | Fword CTF 2021 | ECC, Invalid Curve Attack, RNG | 28/428 |
| Login | Fword CTF 2021 | Hash Extension Attack, RSA Signatures, Unknown Modulus | 11/428 |
| Gold Digger | InCTF CTF 2021 | Jacobi's Symbol | 76/604 |
| Lost Baggage | InCTF CTF 2021 | Custom Encryption System | 52/604 |
| Right Now Generator | InCTF CTF 2021 | RNG | 51/604 |
| Eazy Xchange | InCTF CTF 2021 | ECDH | 44/604 |
| Dhke-intro | UIUCTF CTF 2021 | Brute-force | 166/658 |
| Dhke-adventure | UIUCTF CTF 2021 | Diffie-Hellman, Smooth Primes, Discrete Log | 64/658 |
| Pow-erful | UIUCTF CTF 2021 | Bitcoin Hashes | 16/658 |
| Pythia | Google CTF 2021 | AES-GCM, Partitioning Oracle Attacks | 65/379 |
| Story | Google CTF 2021 | CRC Bit Flipping | 32/379 |
| Scissor | Redpwn CTF 2021 | Caesar Cipher | 1005/1418 |
| Baby | Redpwn CTF 2021 | RSA, FactorDB | 827/1418 |
| Round-The-Bases | Redpwn CTF 2021 | Encodings | 348/1418 |
| Blecc | Redpwn CTF 2021 | ECC, Discrete Log | 146/1418 |
| Yahtzee | Redpwn CTF 2021 | AES-CTR Weak Nonce, Chosen Plaintext Attack | 103/1418 |
| Scrambled-Elgs | Redpwn CTF 2021 | Custom Encryption, Sage | 70/1418 |
| Keeper-of-the-Flag | Redpwn CTF 2021 | DSA, Biased Nonce, SHA-1 Collisions | 42/1418 |
| Retrosign | Redpwn CTF 2021 | Ong-Schnorr-Shamir Signature System | 26/1418 |
| Queen-Of-The-Hill | HSCTF 2021 | Hill Cipher | 514/1165 |
| Opisthocomus-Hoazin | HSCTF 2021 | Char Brute-force, RSA | 376/1165 |
| Regulus-Satrapa | HSCTF 2021 | RSA Bitshifts | 129/1165 |
| Canis-Lupus-Familiaris-Bernardus | HSCTF 2021 | AES-CBC Byte Flipping Attack | 112/1165 |
| Regulus-Regulus | HSCTF 2021 | RSA, Deriving Carmichael Function | 93/1165 |
| Regulus-Calendula | HSCTF 2021 | Algebraic Reconstruction Algorithm, Branch and Prune Attack | 28/1165 |
| Chaos | Zh3r0 2021 | Chaotic Hashes | 50/509 |
| 1n-Jection | Zh3r0 2021 | Custom Scheme, Recursion | 45/509 |
| Challenge | CTF | Category | Solves |
|---|---|---|---|
| oOoOoO | SECCON 2021 | LLL | 26/506 |
| So Easy RSA | HITCON 2021 | RSA, LCG | 56/288 |
| Crypto Warmup | ASIS Quals 2021 | Custom, Primitive Roots, Discrete Logarithms | 147/741 |
| Spiritual | ASIS Quals 2021 | ECC | 60/741 |
| Pryby | K3RN3L CTF 2021 | Custom Scheme | 96/501 |
| Pascal RSA | K3RN3L CTF 2021 | Lucas' Theorem, RSA | 75/501 |
| Tick Tock 🩸 | K3RN3L CTF 2021 | Discrete Logarithm for Genus 0 Curves | 6/501 |
Note : The "🩸" denotes first blood on that challenge.