Method of transmitting information data from a sender to a receiver via a transcoder

A method of transcoding in a transcoder partly encrypted information data received from a sender and to be transmitted to a receiver, whereby said partly encrypted information data comprised non-confidential information data and encrypted confidential information data, and is accompanied by security information and transcoding-type information, said transcoder having access to said security information and transcoding-type information for potential use before transcoding and transmittal of the partly encrypted information, whereby said encrypted confidential information data may only be transcoded without using its content while said non-confidential information data may be transcoded, having access to its content.

A method for receiving from a transcoder in a receiver transcoded partly encrypted information data comprising transcoded non-confidential information data and transcoded encrypted confidential information data, furthermore receiving together with said transcoded partly encrypted information data, security information and transcoding-type information which may be used for comparing it with said transcoded partly encrypted information data for testing the compliance of the transcoding with said security information and transcoding-type information.

A sender for transmitting information data to a receiver via a transcoder, which transcodes said information data comprising confidential information data and non-confidential information data, characterized in that said sender comprises an encryptor for encrypting said confidential information data, and that together with the partly encrypted information data to said transcoder, security information and transcoding-type information is sendable, being usable for said transcoding, whereby said encrypted confidential information data is transcodable without using its content while said non-confidential information data is transcodable, having access to its content.

A transcoder for transcoding partly encrypted information data received from a sender and for transmitting the transcoded partly encrypted information data to a receiver, said received partly encrypted information data comprising non-confidential information data and encrypted confidential information data, and being accompanied by security information and transcoding-type information, said transcoder comprising decision means for deciding which part of said received partly encrypted information data is to be transcoded before transmitting it to said receiver, whereby said encrypted confidential information data is only transcodable without using its content while said non-confidential information data is transcodable.

A receiver for receiving transcoded partly encrypted information data from a sender via a transcoder, said transcoded partly encrypted information data comprising non-confidential information data and encrypted confidential information data, furthermore for receiving together with said transcoded partly encrypted information data, security information and transcoding-type information, comprising comparison means for comparing said security information and said transcoding-type information with said transcoded partly encrypted information data for testing the compliance of the transcoding.