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The flag was encrypted with textbook RSA using a very small public exponent (e=3) and no padding. Don't try to factor n — there's an easier way when the message is small. Recover the flag.
#crypto#rsa#low-exponent#cube-root#intermediate
DifficultyMedium
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Hints
Unlocking any hint — including free ones — forfeits the +25% no-hint solve bonus.
If the exponent is small, such as 3, and the message is short without padding, the ciphertext equals the plain message cubed. Taking an integer cube root then recovers it.
How is this attack prevented?
Use secure padding such as OAEP, which randomizes and expands the message, and choose a standard public exponent like 65537.
Can I solve the challenge with Python?
Yes. Python's big integers and a simple integer root function are enough. The challenge is free on Codelivly and teaches core RSA weaknesses.