T 0170/02 (Controlling access/NEWS DATACOM) 13-04-2005

1. The appeal complies with the requirements referred to in Rule 65(1) EPC and is, therefore, admissible.

2. The patent relates to the general problem of controlling access to television broadcasts (see Figures 1 to 3 and associated text). In particular, it concerns a receiver, comprising a decoder and a portable execution unit (smart card), which contains an algorithm that generates the seed for the descrambler based on data transmitted from the transmitter. As a result, the receiver contains no cryptographic keys. The decoder also contains a "mailbox" that enables messages to be passed to the smart card from both the transmitter and an old smart card. The messages may relate to enabling or credit information, particularly the amount of viewing credit left on an old card when it is replaced by a new card (e.g. on a security update).

Insufficiency of disclosure

3. The respondent has not alleged that the "mailbox" is anything more than a memory store controlled according to the described and claimed functionality. The Board does not doubt that the skilled person would be able to implement such a "mailbox" with the given functionality. Concerning the "enabling" of the second smart card, the original description discloses, at page 6, lines 46 to 47 of the A-publication, that this is based on a message left by the old card. The Board judges that the skilled person would be able to implement an "enabling" based on such a message.

Added subject-matter and interpretation of claims (main request)

4. The negative limitation that the decoder contains "no cryptographic keys" has been deleted from originally filed claim 1. In order for a deletion of a feature to be allowable under Article 123(2) EPC, the skilled person must be able to recognise that the feature is not essential to the invention. The Board judges that the circumstances that imply that a feature is essential are not necessarily identical for positive and negative features in a claim. This may be seen from the fact that the skilled person might not be able to recognise whether an invention would work if a positive feature were to be deleted, whereas he would generally be able to imagine situations where the invention would work despite the presence of a feature contrary to a negative limitation. For example, in the present case, such a feature could be secret cryptographic data resident in the receiver for some purpose entirely unconnected with the invention. Thus, the skilled person would normally need to find stronger reasons to consider a negative feature as essential compared to a positive feature. In the present case, such stronger reasons are not apparent to the Board, the original disclosure rather presenting the negative feature as some kind of additional advantage. Hence, although the originally filed description mentions at page 5, lines 29 to 30 of the A-publication that the lack of cryptographic keys is a "particular feature of the present invention", the Board judges that this is not the same as saying that it essential, so that it may be deleted.

5. The Board agrees with the respondent that the feature of identical operations of the portable executing means that was deleted from originally filed claim 1 cannot be regarded as essential because the amended claim is directed to a single receiver.

6. The Board also agrees with the respondent that the point about whether the descrambler or the smart card generates the seed, turns on the interpretation of the phrase "the descrambler is operative when associated with ... portable executing means, to generate the seed" in the granted claim. However, the Board interprets the phrase rather more broadly than the appellant. The Board judges that the formulation "operative when associated with" is more remote and broader than the strict meaning that the descrambler alone generates the seed. Rather, it means that the descrambler and the smart card are together involved in generating the seed. The role of the descrambler could range from virtually nothing, such as receiving the seed from the smart card, to virtually everything, such as generating the seed when the smart card is plugged in. This interpretation is in line with the different embodiments on file at various stages of the proceedings. On filing, there was an embodiment (page 5, lines 36 to 40 of the A-publication) with no smart card, but just a memory containing data used to reproduce the seed, i.e. the descrambler alone generated the seed. This part of the description was deleted on grant. In one embodiment of the granted patent, the smart card generates the decoding seed (page 4, line 48), i.e. the role of the descrambler is virtually zero. Finally, in another embodiment of the granted patent, the executing means only contains "part of the instructions required to descramble the transmission" (page 2, lines 38 to 39), i.e. both the smart card and the descrambler play a role. This embodiment was deleted in opposition.

7. The Board thus judges that the wording of granted claim 1 covers a wide range of distribution of functions between the smart card and the descrambler. Consequently, the amendment to specify that the seed generating algorithm is executed in the smart card is a restriction to the granted claim and is not an extension of protection. Since this is also supported by the remaining embodiment, it is also not an extension of subject-matter either.

Novelty (main request)

8. Since it is agreed that the mailbox functions only as a store, the Board agrees with the appellant that the buffer store below the sound/data multiplexer 210 in Figure 11 of A2 can also be considered as a "mailbox". A2 thus discloses all the features of claim 1 except for the function of the mailbox.

9. The question then arises whether and to what extent this functional definition limits the claim. Both parties cite Guidelines C-III, 4.8, which states that apparatus for carrying out a process or for a particular use must be construed as meaning merely apparatus suitable for carrying out the process or for the stated use. The appellant considers that this implies in the present case that the mailbox can be any store that can pass data from one entity to another, thus including the buffer store in A2. The respondent argues that the elements cited in A2 are not suitable for the specified purpose.

Although the Guidelines require only that the element is suitable for the intended purpose, the Board judges that this cannot be extended to mean could be suitable for the intended purpose if modified appropriately. Thus, although the store in A2 could be made to pass data between the various parts of the system, the question is whether it does so according to the limitations imposed on the claim by its functional description.

10. In this respect the Board distinguishes between use and function. The passages of the Guidelines cited by the parties deal with the use to which a claim is put, which generally relates to other features that are not within the scope of the claim. The Guidelines give the example of a "mold for molten steel" in which the use relates to molten steel, which is not part of the claim to the mold. On the other hand, in a true functional feature, the function generally relates to features which are within the scope of a claim. For example, the feature in the present claim 1 "mailbox for receiving data from broadcast transmissions and from a first portable executing means" relates to specific data, and if this data is defined in the claim, the claim is limited to receiving this data. In the present case, the data from broadcast transmissions and from a first portable executing means is defined in the claim and the Board judges that the mailbox must therefore be interpreted as being arranged to store this data.

11. The Board agrees with the appellant that A2 discloses at page 6, lines 57 to 59 and lines 63 and 64, that the buffer stores messages that have been transmitted over- air, and therefore data from broadcast transmissions as claimed in the first part of the feature. However, although it is clear from the function of displaying remaining credit described at page 7, lines 9 to 10, that data can be received from the Conditional access sub-system (CASS), e.g. a smart card, the Board judges that it is not disclosed that this data is stored in the buffer store as required by the last part of this feature.

For similar reasons, the Board agrees with the respondent that A2 does not disclose the remaining features of claim 1, namely that the data is received "upon replacement of said first one of said portable executing means with a second one of said portable executing means, providing said data to said second one of said portable executing means, thereby enabling said second one of said portable executing means".

12. The Board accordingly judges that claim 1 is novel (Article 54 EPC).

Inventive step (main request)

13. The Board judges that the differences identified above solve the objective technical problem of enabling a smart card provided by the service provider. The Board judges that the skilled person would consider solving this problem, in particular when the card is replaced "from time to time", or if a major breach of security occurs as disclosed in A2 at page 4, lines 2 to 3.

14. The Board further judges that when enabling a new card it would be obvious to consider replacing any credit remaining on the old card since the loss of money would be annoying to the viewer, in particular if the replacement was initiated by the service provider for security reasons. In order to replace the remaining credit, information must be transferred from where the credit is known, namely from the old card or, possibly from the head end. The latter seems unlikely unless the head end were permanently updated with the credit remaining on the card, which, by analogy with the respondent's argument about downloading credit, would be undesirable owing to the high bandwidth required.

The skilled person would be aware, from A10 for example, that one possible way of transferring credit from one smart card to another is to use an intermediate store. Since A2 discloses, in the bottom right part of Figure 12, that the buffer store may store credit from the head end, the Board judges the skilled person would consider using it as an intermediate store for storing the credit to be transferred from the old to the new card. The Board thus judges that it would be obvious to store credit data received from both the broadcast transmissions (head end) and from the smart card. Finally, it is self evident that the credit data would be transferred upon replacement of the card, as claimed.

15. The respondent argues that the skilled person would only consider transferring data from the head end or the old smart card, but not a combination of both. However, it follows from the above that the Board judges that the transfer of credit from the old card is an obvious addition to the system using over-air credit. Moreover, the claimed transfer of data to the second card is very general, the said data being "data from broadcast transmissions and from a first portable executing means". In particular, there is no specified relationship between the data from the two sources. Thus the claim covers the case where the transfer of data from the broadcast transmission to the second smart card is an independent function. This need not even relate to credit information, but could be any data that the service provider needs to send to the viewer's card.

16. The subject-matter of claim 1 of the main request accordingly lacks an inventive step (Article 56 EPC).

Inventive step (auxiliary requests)

17. The respondent agreed that the auxiliary requests "A", "B", "C", "D" and "F" were fall back positions in the event of a negative judgement on Article 123 EPC, but did not affect the arguments concerning inventive step. Accordingly, they do not involve an inventive step for the same reasons as the main request.

18. There being no other requests, it follows that the patent must be revoked.