MoreText

Platform: CUSTOM | Category: Crypto | Type: Challenge | Difficulty: Medium | OS: N/A | **Author: XESXOR Techniques: Build substitution table from known pairs, Identify source text (Wikipedia article), Known plaintext attack on substitution cipher

Summary

Walkthrough of the CUSTOM Crypto MoreText. Task: Monoalphabetic substitution cipher on Merkle-Hellman Wikipedia article. Solution: Identify source text, build mapping from known plaintext pairs to recover the alphabet permutation.

Description

Monoalphabetic substitution cipher on Merkle-Hellman Wikipedia article.

Solution

Identify source text, build mapping from known plaintext pairs. Flag is the alphabet permutation. ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Key Takeaways / Lessons

• Mastering Build substitution table from known pairs, Identify source text (Wikipedia article), Known plaintext attack on substitution cipher was key to this challenge.
• Always check for common misconfigurations and verify assumptions.

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Crafted by XESXOR Research • 2026-03-08 • CUSTOM • MoreText • Difficulty: Medium