|Rosetta-stone: decryption not even obvoious|
Actually, the decryption was entirely symmetric to the encryption algorithm and the patentee argued that the step of decrypting/deciphering the data was, though implicitly, still clearly and unambiguously disclosed in the parent application for the person skilled in the art. Any economically sensible use of the invention would arguably require a playback of the signals, which would in turn inevitably be preceded by a deciphering.
Given that the German skilled persons usually derive far more implicit information from "between the lines" than skilled persons in other jurisdictions, it was not quite clear how the senate would decide.
The senate did not folow these arguments and confirmed the nullification of the patent.
However, the decisive point was not that the step of decrypting was not explicitly mentioned but that the claims of the divisional application were directed to an "Aliud", i.e. to a "different thing" in the legal sense. This happens in particular where subject-matter is originally disclosed but not disclosed "as belonging to the invention".
According to the senate, the patentee had the possibility to claim encryption and decryption alone or in any combination at the time of filing and has chosen to claim encryption only. Even if steps other than the encryption step were clearly unavoidable and an enabling disclosure for these steps would have been given, the skilled person would not have considerd these steps a "belong to the invention" in the absence of any indications in this regard.
The case emphasizes the necessity to duly consider every possible technical context in which an invention could eventually be used when drafting a claim set.
The full decision can be read (in German) here: BGH X ZR 130/11 "Verschlüsselungsverfahren"
Posted by Michael Thesen