CTF Cryptography

Quick reference for crypto challenges. For detailed techniques, see supporting files.

Additional Resources

• prng.md - PRNG attacks (Mersenne Twister, LCG, time-based seeds, password cracking)
• historical.md - Historical ciphers (Lorenz SZ40/42)
• advanced-math.md - Advanced mathematical attacks (isogenies, Pohlig-Hellman, LLL, Coppersmith)

ZKP Attacks

• Look for information leakage in proofs
• If proving IMPOSSIBLE problem (e.g., 3-coloring K4), you must cheat
• Find hash collisions to commit to one value but reveal another
• PRNG state recovery: salts generated from seeded PRNG can be predicted
• Small domain brute force: if you know commit(i) = sha256(salt(i), color(i)) and have salt, brute all colors