cryptographic keys for use with the Web Cryptography API. Pre-provisioned keys are
keys which have been made available to the UA by means other than the generation,
derivation, importation and unwrapping functions of the Web Cryptography API. Origin-specific
keys are keys that are available only to a specified origin. Named keys are identified
by a name assumed to be known to the origin in question and provisioned with the key
itself. This note concerns only keys which have all three of these properties.