問題文
A shipping line accepts booking instructions by email. A customer later denies having sent an instruction that cost the line money, and the line cannot show otherwise. Which property was missing from the arrangement?
選択肢
- Availability, because the shipping line was unable to retrieve the original instruction from its own mail archive at the moment when the customer raised the dispute about the charge that had been applied.
- Nonrepudiation because the line held no evidence tying the instruction to the customer in a form the customer could not later disown, such as a signature only the customer could produce.
- Confidentiality, because an instruction sent by ordinary email travels in a form that other parties on the path are able to read while it is in transit between the customer and the shipping line.
- Integrity, because the shipping line has no way of proving that the wording of the instruction it acted on was exactly the wording that the customer had originally typed into the message.