bulk key

In a few published descriptions of hybrid encryption for SSH, Windows 2000, and other applications, this term refers to a symmetric key that (a) is used to encrypt a relatively large amount of data and (b) is itself encrypted with a public key. (Compare: bulk keying material, session key.)

Example: To send a large file to Bob, Alice (a) generates a symmetric key and uses it to encrypt the file (i.e., encrypt the bulk of the information that is to be sent) and then (b) encrypts that symmetric key (the "bulk key") with Bob's public key.

Deprecated Term: IDOCs SHOULD NOT use this term or definition; the term is not well-established and could be confused with the established term "bulk keying material". Instead, use "symmetric key" and carefully explain how the key is applied.