Abstract: An arrangement for sterile handling of a non-sterile endoscope in a sterile environment. The arrangement includes a sterile endoscope sheath, and the non-sterile endoscope. The sterile endoscope sheath has an optical element arranged at a distal end of the sterile endoscope sheath. The non-sterile endoscope has an endoscope shaft with an optical element arranged at a distal end of the endoscope shaft.

Abstract: A secure method for sending registered, authenticated electronic documents. The invention validates sender and recipient identities, provides for non-repudiation of authenticated documents by sender and recipient, provides an evidence trail, and protects the integrity of the document. The invention is constructed so that a sender can be supplied with proof that the intended recipient received and opened an authenticated document. A neutral third party acts as a document registration agent, and witness to the transmission and receipt of the authenticated document. In the event of a dispute between sender and recipient, the third party can provide an irrefutable record of the contents of the document and of the history of the transmission and receipt of the document Because the third party never has possession of the electronic document, the method provides maximum privacy for sender and recipient. The method is readily adaptable to both key recovery and key escrow.