Return receipt

The acknowledgment of receipt, a brief written evidence is referred to, that one has received a commodity, an item or a message in general.

Examples

A letter may be entrusted with return receipt requested, so that the sender receives a receipt signed by the recipient.

The German law recognizes the service delivery against receipt, for example in the delivery of lawyers ( § 174 ZPO).

For several years, many delivery services with palmtop computers are equipped, on the display of the receiver directly makes his signature.

Furthermore, there are receipts in e- mails, see Message Disposition Notification.

Acknowledgment problem

The acknowledgment is a problem unsolved problem in computer science and information security. The aim is to produce a receipt, which does not rely on the goodwill of the message recipient. For all known types of receipts has been shown that they can be falsified or suppressed or require the assistance of an independent third party. Today's solution attempts are often made ​​with means of cryptology.

Background

Frequently there is a need on the part of the sender, that the receipt of a message or goods to the consignee is detectable. The classic signed acknowledgment of receipt serves this purpose, if the communication partners cooperate. However, it fails if the recipient wants to manipulate the process. For a fake confirmation by the original sender is the (also electronic ) signature of the acknowledgment a suitable means. The embezzlement of confirmation by the original sender ( assertion: The recipient has not confirmed) can be countered by the original recipient itself requests an acknowledgment for the receipt of the acknowledgment. Thus, the problem shifted by only one digit.

The basic problem, then, is that the recipient of a message can receive them and can conceal this fact or claim the opposite. In practice, therefore, an independent third party be called as witnesses or it is assumed in some cases that the message or of the merchandise was received.

The solution uses cryptography resists the problem in that the cryptographic keys must be under control of their owner. To ensure the authenticity of the receipt it must be signed by the original recipient. This can not be done by anyone other than the key holder of principle. The key holder can therefore refuse to produce the receipt.