Challenge

A ciphertext that looks like a scrambled boroCTF flag.

Approach

The title “Et Tu Brute” is a direct reference to Brutus — and Caesar. Try all 25 shifts; shift 3 (ROT3) yields the plaintext:

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ct = "eroCTF{@fi13qaq0prj3}"
# shift each alpha char by -3 mod 26
def caesar(s, n):
    result = ""
    for c in s:
        if c.isalpha():
            base = ord('A') if c.isupper() else ord('a')
            result += chr((ord(c) - base - n) % 26 + base)
        else:
            result += c
    return result

print(caesar(ct, 3))

Flag

boroCTF{@fr13ndn0mor3}