The present invention consists of a method and apparatus for authenticating an electronic document. In one embodiment of the invention, a party wishing to digitally sign an electronic document (the "client") stores the unsigned electronic document, and the client's public and private keys, on transportable storage media such as a floppy disk. The client conveys the storage media to an authorized electronic document authenticator. An authorized electronic document authenticator is an individual or enterprise that has access to the apparatus of the present invention or that has been authorized to use the method of the present invention. The client presents identity documents to the authenticator to verify the client's identity. The client digitally signs the electronic document in the presence of the authenticator.; The authenticator verifies the digital signature using the public key provided by the client. Having witnessed the client digitally signing the electronic document using the client's private key, having verified that the public key supplied to the authenticator by the client corresponds to the private key used by the client to produce the digital signature, and having verified the identity of the client using the identification documents provided by the client and/or biometric measurements taken of the client, the authenticator appends an "authenticator identification envelope" containing a certification to that effect to the electronic document. In one embodiment of the invention, the authenticator identification envelope includes digitally recorded biometric data obtained from the client.; The authenticator digitally signs the resulting electronic document, creating an authenticated electronic document. The authenticator transfers the completed, authenticated electronic document onto transportable storage media and returns it to the client.