Thus, if a user forgets to log out when finished or leaving the office, anyone who has internal or physical access to that computer can open that person's files. Network administrators can combat this problem by automatically logging users off after a certain period of inactivity, but constant prompts for passwords can cut into productivity as well as annoy everyone in the firm. Network logon prompts are also ineffective for notebook computers, which by nature are often used unconnected to a network. In addition, the portability of notebooks allows thieves to employ more elaborate hacking methods in the comfort of their own lairs. One common method used to protect key data is to encrypt sensitive files, which provides a level of security that logon prompts cannot match.
Encryption is also readily available.
There are two methods to encrypt files. Symmetric key encryption uses the same password to encrypt and decrypt data. This type of encryption has one major shortcoming. In situations in which the encrypted data is shared, a secure channel is required to give the password to the recipient. This defeats the purpose of encryption, because if users had a secure channel, they would not need to encrypt their data.