# Overview

You can use digital certificates in place of preshared keys for IKE negotiations. For more information about IKE, see IKE Overview in Configuring IPSec.

## Digital Certificate Terms and Acronyms

Table 14 describes terms and abbreviations that are used in this discussion of digital certificates.

Table 14: Digital Certificate Terms and Acronyms

Term or Abbreviation | Description
--- | ---
3DES | Triple DES encryption/decryption algorithm
Base64 | Method used to encode certificate requests and certificates before they are sent to or from the CA
CA | Certificate authority; an organization that creates digital certificates
Certificate | Binds a person or entity to a public key using a digital signature
CRL | Certificate revocation list; a list of certificates that a CA has revoked
ESP | Encapsulating Security Payload; provides data integrity, data confidentiality and, optionally, sender's authentication
IKE | Internet Key Exchange
PKCS | Public-Key Cryptography Standards; a series of standards established by RSA Laboratories
PKCS10 | PKCS #10; describes a syntax for certification requests
Root CA | CA that signs the certificates of subordinate CAs
Root certificate | Self-signed public key certificate for a root CA; root certificates are used to verify other certificates
RSA | Rivest-Shamir-Adleman encryption algorithm
SA | Security association; the set of security parameters that dictate how IPSec processes a packet, including encapsulation protocol and session keys. A single secure tunnel uses multiple SAs.
SCEP | Simple certificate enrollment protocol; used to submit requests and to download certificates and CRLs