That protection covers the too-common circumstance of authorized users who, intentionally or accidentally, share their VPN access credentials with a hacker. With personal computers, Unix servers, and workstations running at head-spinning speeds, the question sometimes arises as to why anyone needs so much processing power. Pundits often cite the need to run more capable applications and to scale Internet services to thousands of users, but VPNs create a more pressing need for fast computers. A VPN uses encryption to ensure that a hacker capturing your WAN packets sees only indecipherable garbage. That's no small challenge.
Encryption is based on the kind of mathematical calculations that fill a blackboard.
Every VPN packet is transmuted by a series of calculations intended to make it impossible to restore the packet to its original form except by its intended recipient. The stronger the encryption, the more computing time it takes to encrypt or decrypt each packet. The strongest encryption techniques require more computing power than most companies can afford, given the volume of data they handle. The network-services architects who must devise a sound VPN strategy face three primary challenges. First, an encryption technology must strike a balance between protection and computing requirements.