Abstract: Cryptographic keys for a cryptographic function are notarized by encrypting the keys with the cryptographic function using a notarizing cryptographic key derived from identifier designations associated with the encryptor and intended decryptor, respectively, and an interchange key which is accessible only to authorized users of the cryptographic function. Preferably, the identity of a user of the cryptographic function is authenticated as a condition to access to an interchange key. Advantageously, authentication is accomplished by comparing a password designation supplied by the user with a prestored version thereof which has been notarized by having been encrypted with the cryptograpic function using a notarizing cryptographic key derived from the identifier designation of the corresponding authorized user and an interchange key. Signature properties similar to those provided by public key systems are provided for nonpublic keys by allowing a user to use a key for only encryption or decryption and not both.