Encryption is the use of secret codes that can be translated into meaningful communications only by authorized persons who have knowledge of the code. Encryption has been studied and employed for decades by governments and militaries. For example, a primary function of U.S. intelligence agencies during World War II (1939–45; war in which Great Britain, France, the Soviet Union, the United States, and their allied forces defeated Germany, Italy, and Japan) involved deciphering German military codes that had information about the movements and missions of German submarines.
The Internet has opened up new uses for encryption, many of which are designed to deter online criminal activity. Companies add encryption into important files like trade secrets. If a hacker gets into their network, the files will be meaningless to him. Companies can encrypt important data such as credit card numbers to protect their customers. This tactic is being used on an increasing basis to reduce Internet fraud and identity theft.
Just as encryption is beneficial to Internet users, its features attract cyber criminals. Cyber criminals encrypt communication and the stored files of their activities. Law enforcement agencies cannot usually obtain wiretaps for a criminal's phone, so encryption often keeps the secrets of cyber criminals safe. Public safety is at risk when criminals including terrorists encrypt communication. Should a code be broken by a law enforcement agency, the criminal can easily and quickly switch to another coding system. In 2004 U.S. law enforcement agencies, including the FBI, constantly asked Congress to designate more and more money for technology to fight cyber criminal encryption.