Encryption
Encryption has long been used by militaries and governments to facilitate secret communication. It is now commonly used in protecting information within many kinds of civilian systems. For example, the Computer Security Institute reported that in 2007, 71% of companies surveyed utilized encryption for some of their data in transit, and 53% utilized encryption for some of their data in storage. Encryption can be used to protect data "at rest", such as information stored on computers and storage devices (e.g. USB flash drives). In recent years, there have been numerous reports of confidential data, such as customers' personal records, being exposed through loss or theft of laptops or backup drives; encrypting such files at rest helps protect them if physical security measures fail. Digital rights management systems, which prevent unauthorized use or reproduction of copyrighted material and protect software against reverse engineering (see also copy protection), is another somewhat different example of using encryption on data at rest.
Packet capture appliance
Some packet capture appliances encrypt the captured data before saving it to disk, while others do not. Considering the breadth of information that travels on a network or internet connection and that at least a portion of it could be considered sensitive, encryption is a good idea for most situations as a measure to keep the captured data secure. Encryption is also a critical element of authentication of data for the purposes of data/network forensics.