In the Embassies area of the Citadel, I talked to an officer named Delk. He's requesting I find some Cerberus ciphers for him. The specific quest text is as follows:
A C-Sec officer needs updated ciphers to break Cerberus codes. Find the ciphers and deliver them to him, at the Citadel embassy.
Where are the ciphers, and what is the reward for returning them to Delk?