There are 9 codes and keys altogether, the last one which is given to you:
Personnel Module
Operations:
Locker Room:
1. Sareh Hasmadi locker code: 0315
2. Clive Siddiqi locker code: 1407
-Pick up key in locker
Clive's Personal Quarters:
3. Insert key to open drawer under Clive's bed
Administration:
Conference Room:
4. Administrator's Office door code: 1228
Biomedical Module
Botany:
5. Irrigation door code: 0281
Medical:
Exam Facilities:
6. Recent Body Scans console code: 2080
-Pick up key in desk drawer in Medical Office
Medical Storage:
7. Insert key to open Secure Medical Storage
Engineering Module:
Mechanical Engineering:
Drone Bay:
8. Door at back of room code: 0809
Network Technology (door initially locked until you go into or through Mechanical Engineering):
Open door on upper level:
9. Code given to you: 0451 (reference to famous code in Deus Ex)
Achievement will pop after the credits.