In cryptography, encryption is the process of obscuring information to make it unreadable without special knowledge. While encryption has been used to protect communications for centuries, only organizations and individuals with an extraordinary need for secrecy have made use of encryption. In the mid-1970s, strong encryption emerged from the sole preserve of secretive government agencies into the public domain, and encryption is now employed in protecting widely-used systems, such as Internet e-commerce, mobile telephone networks and bank automatic teller machines.
Encryption can be used to ensure secrecy, but other techniques are still needed to make communications secure, particularly to verify the integrity and authenticity of a message, which encryption cannot do; for example, a message authentication code (MAC) or digital signatures. Another consideration in addition to encryption is protection against traffic analysis.