Crypto
Looks like the oracle took a nice long holiday and her apprentice had to cover for her. She's new to the job so if she forgets anything... you'll just have to deal with it. Good luck !
TL;DR :
send -1, as dec(-1) <=> n - 1
send 2 and recover e (using 2 and dec(2)
send c * enc(2), as dec(c * enc(2)) <=> m * 2 and divide to get m
Hero{m4ybe_le4ving_the_1nt3rn_run_th3_plac3_wasnt_a_g00d_id3a}