Abstract: To ensure the data corresponding to transactions has not been altered, a method and system are provided for generating secure endorsed transactions having transaction data representative of transactions and unique identifiers corresponding to parties endorsing the transactions. After receiving input, including transaction data and unique identifiers, unique codes are generated from the transaction data and unique identifiers. The unique codes constittue secure endorsements of the transaction data by the parties corresponding to the unique identifiers.

Abstract: An apparatus and method of copy protection for use in digital data recorders such as DVD-RAM recorders, which includes embedding transmission time information into a digital data stream by digital watermarking and comparing the transmission time with the current time at the data recorder (30, 50). If the time difference is less than a threshold value it is presumed that the recording is for time-shifting purposes, namely recording a programme to watch later, which is generally allowed by copyright laws. If the time difference is greater than a threshold value it is presumed that the recording is an attempted unauthorised recording such as from a pre-recorded copy, and further recording is prevented.