For this challenge, we are given a jpg file.
Analyzing the file, the symbols tell us that they represent an alphabet/substitution cipher. The hint is a reference to a line Caesar utters while being stabbed to death in the play Julius Caesar by William Shakespeare.
Doing some research, we find that Caesar was stabbed to death by daggers and we discover there is an alphabet using daggers.
Translating from the Daggers Alphabet to English, we get riftctfbonjourelliot.
Flag: riftCTFbonjourelliot