| Abbreviation | Definition |
|---|---|
| OASIS | Orbis Advanced Security Intruder System |
| OATH | Open AuTHentication |
| OBB | Orange Book Blog |
| OCB | Offset Code Book |
| OCB | Operational Cipher Block |
| OCSG | Open Computing Security Group |
| ODBE | Original Dynamic Broadcast Encryption |
| ODFP | Outlook Data File Password |
| ODI | Open Datalink Interface |
| ODM | Originally Detectable and Masked |
| ODMR | On-Demand Mail Relay |
| OEC | Offshore Engineered Component |
| OEL | Occupational Exposure Limit |
| OIAP | Object-Independent Authorization Protocol |
| OMP | Online Media Protection |
| ONC | OpenNet Controller |
| ONE | Optimized Network Encryption |
| ONVIF | Open Network Video Interface Forum |
| OOBA | Out Of Band Authentication |
| OPA | Online Privacy Alliance |