| DCE | distributed-computing environment |
| DCOM | Distributed Component Object Model |
| DER | Distinguished Encoding Rules |
| DES | Data Encryption Standard |
| DH | Diffie-Hellman |
| DMZ | demilitarized zone |
| DN | Distinguished Name |
| DNS | Domain Name Service |
| DSA | Digital Signature Algorithm |
| DTD | document type declaration |