Erlang

Platform: CUSTOM | Category: Reversing | Type: Challenge | Difficulty: Easy | OS: N/A | **Author: XESXOR Techniques: caesar_cipher_reverse, source_code_analysis

Summary

Walkthrough of the CUSTOM Reversing Erlang. Language: Erlang. Source code provided. Caesar cipher checker.

Description

Language: Erlang. Source code provided. Caesar cipher checker.

Analysis

The program applies a Caesar cipher with shift 3 to the input and compares it with the target string:

 erlang read-only • copy allowed Copy
Caesar = fun(A) -> (A - ord("a") + 3) rem 26 + ord("a") end,
Caesared = lists:map(Caesar, Flag),
case string:equal(Caesared, "yhqlylglkdfnhulfl") of

Solution

Reverse Caesar shift by 3 positions:

 python read-only • copy allowed Copy
target = "yhqlylglkdfnhulfl"
flag = ''.join(chr((ord(c) - ord('a') - 3) % 26 + ord('a')) for c in target)
# REDACTED

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This is the Latin phrase "veni vidi" + "hackerici" (a parody of "veni, vidi, vici"). ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Key Takeaways / Lessons

• Mastering caesar_cipher_reverse, source_code_analysis was key to this challenge.
• Always check for common misconfigurations and verify assumptions.

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Crafted by XESXOR Research • 2026-03-09 • CUSTOM • Erlang • Difficulty: Easy