Crypto

A homemade LCG-as-cipher multiplies each flag byte by a deterministic state independent of the plaintext — the known DalCTF{ prefix recovers one state, and replaying the generator divides out the rest. The lost seed is a red herring.

A C program squares each flag byte as a float, then a ‘forgotten’ Quake-style (long)&y type-pun prints the raw IEEE-754 bits as integers; reversing bits→float→sqrt→char recovers the flag.

A commit-reveal rock-paper-scissors whose non-binding sha256(r1 + message + r2) commitment lets you open one hash to any winning move and sweep all 100 rounds.

A P-521 ECDSA oracle derives its nonce from an MD5-based uuid3, so an MD5 collision forces nonce reuse, leaks the private key, and lets us forge a signature for the flag.