Streamcipher information redundant in next packet of encrypted frame

A method for receiving and decrypting frame-based information from a transmission medium, with payload information of a particular frame being assigned to one or more transmission packets and having the payload information of such frame encrypted through a frame encryption key, and each transmission packet being provided with individual streamcipher-based synchronization information for in combination with the frame decryption key enabling said decrypting of an associated encrypted transmission packet,

• said method being characterized by receiving said streamcipher-based synchronization information as being redundantly included in a second transmission packet that is next to the first transmission packet originating the individual streamcipher-based synchronization information in question as a seed information for decrypting said second transmission packet.

A device for transmitting frame-based information through a transmission medium, said device comprising assigning means for assigning payload information of a particular frame to one or more transmission packets, and encrypting means for encrypting the payload information of such frame through a frame encryption key, and having streamciphering means for providing each transmission packet with individual streamcipher-based synchronization information for in combination with the frame decryption key enabling decrypting of an associated encrypted transmission packet,

• said device being characterized by having inserting means for inserting for transmission of said streamcipher-based synchronization information as being redundantly included in a second transmission packet that is next to the first transmission packet originating the individual streamcipher-based synchronization information in question as a seed information for decrypting said second transmission packet.

A device for receiving and decrypting frame-based information from a transmission medium, with payload information of a particular frame being assigned to one or more transmission packets and having the payload information of such frame encrypted through a frame encryption key, and having frame decrypting means for decrypting each transmission packet that is provided with individual streamcipher-based synchronization information associated to streamcipher decrypting means for in combination with the frame decryption key enabling said decrypting of an associated encrypted transmission packet,

• said device being characterized by having selecting means for selecting said streamcipher-based synchronization information through its being redundantly included in a second transmission packet that is next to the first transmission packet originating the individual streamcipher-based synchronization information in question as a seed information for said decrypting means for decrypting said second transmission packet.