1. < database > A value used to identify a record in a database, derived by applying some fixed function to the record. The key is often simply one of the fields (a column if the database is considered as a table with records being rows, see " key field "). Alternatively the key may be obtained by applying some function, e.g. a hash function , to one or more of the fields. The set of keys for all records forms an index . Multiple indexes may be built for one database depending on how it is to be searched.
2. A value which must be fed into the algorithm used to decode an encrypted message in order to reproduce the original plain text . Some encryption schemes use the same (secret) key to encrypt and decrypt a message, but public key encryption uses a "private" (secret) key and a "public" key which is known by all parties.
3. An electromechanical keyboard button.
(2003-07-04)