| Abbreviation | Definition |
|---|---|
| MAA | Message Authentication Algorithm |
| MAAM | Modular Authentication and Authorization Middleware |
| MAAWG | Messaging Anti-Abuse Working Group |
| MAC | Message Authentication Code |
| MACI | Multiple Access Cryptographic Interface |
| MACID | Medium Access Control IDentifier |
| MACS | Monitor And Control System |
| MAIS | Murdoch Authentication and Identification System |
| MAPS | Mail Abuse Protection System |
| MASK | Modified Advanced Standard Key |
| MASKM | Modified Advanced Standard Key Management |
| MASKMM | Modified Advanced Standard Key Management Module |
| MB | MegaBytes |
| MBAE | MalwareBytes Anti-Exploit |
| MBAM | Malware Bytes Anti-Malware |
| MCFA | Mirox Cyber Force Academy |
| MCG | Meta Certificate Group |
| MCRC | Malicious Code Research Center |
| MD | Mini-Disk |
| MDC | Message Digest Cipher |