Encryption technologies come in many forms. A Hardware Security Module (HSM) is a physical computing device that safeguards and manages digital keys for strong authentication and provides crypto-processing. Because HSMs are often part of a mission-critical infrastructure such as a public key infrastructure or online banking application, HSMs can typically be clustered for high availability. Bulk Encryption refers to high-speed link encryption to secure site to site communications. Many ADC and Gateway vendors also offer encryption features such as reverse proxy and VPN technologies.