Et tu, Brute?

Platform: CUSTOM | Category: Crypto | Type: Challenge | Difficulty: Easy | OS: N/A | **Author: XESXOR Techniques: Binary file Caesar, Byte-level shift cipher brute-force (256 values)

Summary

Walkthrough of the CUSTOM Crypto Et tu, Brute?. Task: Binary file with 25 bytes encrypted with byte-level Caesar cipher. Solution: Brute-force all 256 byte shifts, shift 155 reveals the flag.

Description

Binary file with 25 bytes. Byte-level Caesar cipher.

Solution

Try all 256 byte shifts. Shift 155 produces: spbctf{REDACTED} ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Key Takeaways / Lessons

• Mastering Binary file Caesar, Byte-level shift cipher brute-force (256 values) was key to this challenge.
• Always check for common misconfigurations and verify assumptions.

---

Crafted by XESXOR Research • 2026-03-08 • CUSTOM • Et tu, Brute? • Difficulty: Easy