key
1. Information (usually a sequence of random or pseudorandom binary digits) used initially to set up and periodically change the operations performed in crypto-equipment for the purpose of encrypting or decrypting electronic data, for determining electronic counter-countermeasures patterns (e.g., frequency hopping or spread spectrum ), or for producing other key.
Note: “Key” has replaced the terms “variable,” “key(ing) variable,” and “cryptovariable. ” [NIS]
2. Usually a sequence of random or pseudorandom bits used initially to set up and periodically change the operations performed in crypto-equipment for the purpose of encrypting or decrypting electronic signals, or for determining electronic counter-countermeasures patterns(e.g., frequency hopping or spread spectrum), or for producing other key. [INFOSEC-99]
3. A sequence of symbols that controls the operations of encipherment and decipherment [7498-2].