In case M is small is it possible to recover the message In the plain RSA encryption, suppose $N$ is 1024 bits and the public key $e = 17$. Is it secure to use this setting to encrypt very small message, say $3 \leq m \leq 9$? In other words, is it possible for the attacker to recover the message $m$ given the public key and the ciphertext $c = m^e \mod N$.
No its not secure. As this is homework my hint is: Textbook (plain) RSA encryption is deterministic, and so encrypting the same message always gives the same...