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.
Database encryption
Asymmetric encryption expands on symmetric encryption by incorporating two different types of keys into the encryption method: private and public keys. A public key can be accessed by anyone and is unique to one user whereas a private key is a secret key that is unique to and only known by one user. In most scenarios the public key is the encryption key whereas the private key is the decryption key. As an example, if individual A would like to send a message to individual B using asymmetric encryption, he would encrypt the message using Individual B's public key and then send the encrypted version. Individual B would then be able to decrypt the message using his private key. Individual C would not be able to decrypt Individual A's message, as Individual C's private key is not the same as Individual B's private key. Asymmetric encryption is often described as being more secure in comparison to symmetric database encryption given that private keys do not need to be shared as two separate keys handle encryption and decryption processes.