An early security system from Telcordia Technologies (formerly Bellcore) 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 userid 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. New and improved cryptography methods have surpassed S/key in popularity.