Et tu, Brute?

Platform: spbctf | Category: Crypto | Type: Challenge | Difficulty: Easy | OS: NA | Author: XESXOR | Date: 2026-03-08 | Status: Solved Techniques: Binary file Caesar, Byte-level shift cipher brute-force (256 values)

Summary

Task: Binary file with 25 bytes encrypted with byte-level Caesar cipher. Solution: Brute-force all 256 byte shifts, shift 155 reveals the flag.

Et tu, Brute? — cryptokids20

Description

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

Solution

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