| Abbreviation | Definition |
|---|---|
| CID | Card Identification Digit |
| CID | Cooperative Intrusion Detection |
| CIP | Complete Internet Protection |
| CIRC | Computer Incident Response Capability |
| CISP | Cardholder Information Security Program |
| CISPA | Cyber-Intelligence Sharing and Protection Act |
| CK | Clear Key |
| CK | Crypto Key |
| CKDS | Cryptographic Key Data Set |
| CL | Counter Lock |
| CLASP | Comprehensive, Lightweight Application Security Process |
| CLSID | Computer Licence Security ID |
| CM | Codebook Mapping |
| CM | Cryptological Mathematics |
| CMA | Control and Monitoring Agent |
| CMC | Certificate Management protocol using CMS |
| CME | Cellular Message Encryption |
| CMEA | Cellular Message Encryption Algorithm |
| CMK | Complete Match Key |
| CMMI | Capability Maturity Model - Integrated |