DalCTF 2026 Writeup: All 9 Challenges Solved
Platform DalCTF 2026 (dalctf2026.com) Difficulty Mixed (Easy → Medium) OS Jeopardy — Crypto, Reverse Engineering, Web, Android Tags RSA modulus with small prime factor recovered by trial division, Bellcore CRT fault attack as the verification path, Playfair decryption against an un-keyed alphabet square, Huffman tree decode with inverted tiebreaker convention, LCG state recovery from one known plaintext byte, IEEE-754 bit-pattern reinterpretation via Quake-style float pointer cast, UPX-packed ELF unpacked into 44 per-byte check functions, Android APK static-string mining across MainActivity + strings.xml + ColorKt, HTML hidden attribute as a flag-hiding sink DalCTF 2026 is the DalCTF Jeopardy event with challenges spread across Crypto, Reverse Engineering, Web, and Android. The 2026 edition leans heavily into classical cryptography mistakes wrapped in misdirection — six of the nine challenges are crypto, and almost every one of them tries to push you toward a harder attack than the one that actually works. The flag format is dalctf{...} (occasionally DalCTF{...}), and the challenge names are explicit hints once you’ve solved them. ...