Definition: S/key

An early security system from Telcordia Technologies that eliminated sending the same password over the network each time the user logs on. A series of passwords were generated at one time, and each password was used only once. The host system stored only the last password; for example, if 99 passwords were generated, it held password 99 along with the user ID and random number used to seed the hashing process that created them. In the next session, the user would log in with password 98, then 97 and so on. Improved cryptography methods surpassed S/key in popularity.