The RSA Cipher

This asymmetric key cipher was invented in 1977 by three MIT researchers who gave their names to the system: Ronald Rivest, Adi Shamir and Leonard Adleman. At the time the cost of distributing and maintaining encryption keys was becoming prohibitively expensive for organizations such as banks that needed secure communication. RSA provided the perfect solution allowing the public key to be freely published and requiring only the private key to be kept secret. The added benefit is that the process works in reverse: a message encrypted with the private key can be read by anyone but could only have come from one person. When combined with a hashing algorithm RSA can create a digital signature ensuring that a digital message cannot be been tampered with. Furthermore if both the sender and the receiver of such a message use RSA they can both be certain of each others identity, a concept known as non-repudiation.

It can be argued that the growth and success of the Internet through the World Wide Web has been due to massive commercial investment. Commercial activity would not have been possible without cheap and simple secure communication. For better or for worse without RSA we would not have Google, eBay or Wikipedia.

Submitted by: Matthew Webster