Markus Kuhn, 2000-03-16
In this text, I have tried to collect my answers to questions, which I have been asked most frequently about the VideoCrypt pay-TV access control system used by British Sky Broadcasting and my Season7 software smartcard emulator for it.
[Warning: this page is not actively maintained any more and is out of date. It is of historical interest only, because on 1 October 2001, BSkyB stopped broadcasting analog TV using the VideoCrypt conditional access system. They now broadcast only digital TV protected by VideoGuard DVB, which is incompatible with Season7.]
Q: Where can I get the latest Season7?
My latest version is Season7 3.2 published 1996-08-07. This version does not contain the cryptographic functions of any subscriber smartcards, but it is still usable as a VCL recorder and player.
Q: Will I need a new adapter hardware for emulating the BSkyB 10/11/12/... card?
No. Nothing in the decoder has changed, so you won't need a new ISO 7816 interface design. What looked like additional contacts on the series 10 card and what has confused many people who do not understand how a VideoCrypt decoder works is just the changed chip module cover design. There are no new contacts on the BSkyB 10 card. PC-based card emulators won't need a new interface hardware design as long as the decoder is not modified. The BSkyB 10 chip module was larger than previous versions, because the new card contains apart from a Siemens security microcontroller also a customer specific chip (ASIC) designed for BSkyB, in order to make reverse engineering of the new card much more difficult.
Q: When will a hack of the current BSkyB card be available again?
On 1995-10-31, BSkyB has changed to a new secret encryption method, which is built into the series 10 card that was introduced shortly before. This algorithm has never become publically known, although it was independently reconstructed by two commercial pirates in Ireland and Germany. Therefore, it was not possible to upgrade PC-based card emulator software like Season7 and its derivates. BSkyB is currently using the series 12 card. BSkyB and NDS (formerly News Datacom) have successfully taken action against the commercial pirates of the series 10 card, and although the series 11 and 12 cards have again been broken by specialists, they decided not to make this publicly visible. Thanks to its continued exposure to a very aggressive piracy market, NDS has now learned to produce what are probably the most secure smartcard processors on the market and to react proactively in a carefully observed clone card market. In addition the pay-TV broadcasters have persuaded the European Commission to pass Directive 98/84/EC, which requires EU member countries to make commercial pay-TV cloning illegal by May 2000. It is therefore quite unlikely that the new cards will be compromised publically any time soon.
The exchange of the card means that practically all known secrets of the old card become useless. Card emulators can not be simply constructed by just listening long enough to the data traffic of a genuine card. If you do not understand why, then please consult the Frequently Asked Questions List of the USENET group sci.crypt or any good introductory text about cryptography and make yourself familiar with secure hash functions, digital signatures, symmetric cryptosystems and other cryptographic concepts used in the VideoCrypt system.
If at all, commercial hackers might obtain the software in the microprocessor of a new smartcard generation by using very expensive semiconductor test equipment (microprobers, lasers, electron beam testing, electron microscopes, nasty chemicals, layout reconstruction software, etc.) and tricky analysis techniques. Of course the manufacturers of the security microprocessors used in the VideoCrypt cards work hard on making these attacks on the chip as difficult and as expensive as possible. With each card generation they are getting better and better and hacking the cards becomes more difficult and expensive each year, although it is still far from impossible for a skilled hardware security specialist.
Please do not ask me whether the emulator algorithm for the BSkyB 12 card is already available. If the new code becomes publically known, you can be sure that this event will be discussed in detail on the USENET group alt.satellite.tv.crypt. Follow the discussions there if you want to stay informed about the latest progress and rumors.
Q: Where will I find new information about Season7 and VideoCrypt?
Read regularly the USENET newsgroup alt.satellite.tv.crypt. Please do not flood this group with questions before you have not read the various Frequently Asked Questions Lists (FAQs) posted there periodically and before you have not followed the discussions there for at least two weeks. Also, please check the following Internet servers for the latest information, before you start asking questions:
These servers have files with links to additional sources of information.
Remember: While asking a question on the network, you have a much better chance to get a valuable answer, if you demonstrate that you have done your homework and have checked already all available sources of information yourself.
Remember: Be very careful with starting unknown software downloaded from the Internet!!! Some people enjoy publishing files with interesting names like season12.zip which do nothing but destroying data on your harddisk when started. Such software is called a "Trojan Horse" and there have been many reported cases. If a virus scanner does not signal any danger, then this does not mean that this software will do no harm. Never start dubious software without a full prior harddisk backup, especially if you use an operating system like DOS, OS/2, or Windows which has no protection mechanisms.
Q: Is there any way I can still watch Star Trek, the X-Files and the Simpsons on Sky1 even if the 11 card is not yet hacked?
Yes. The technique is known as delayed data transfer and this is one of the security problems of VideoCrypt from which the system can not recover easily by a card exchange. It works as follows:
Someone with a genuine card records the data exchanged between the card and the decoder during the time when a very popular show is broadcasted. I have developed a special data file format called VCL (VideoCrypt Log) exactly for this purpose. People without a genuine card record the encrypted show on a good VCR at the same time. Later, the person with the genuine card posts his VCL file on a mailing list and all people without real cards load this VCL file with Season7. Then Season7 can reproduce the answers of the genuine card and this is sufficient for decoding this show even without knowing the secret cryptographic algorithm.
This works fine and has even been done when the 07 card was in use. It just needs a little bit cooperation on the network. The person recording the VCL file will need an adapter card which has a card connector, so that the adapter can be plugged between the decoder and card. In order to decrypted from a VCR, you'll have to make a special cable which allows to connect the VideoCrypt decoder between the VCR and the TV. This does not work with most IRDs. The technical details are explained in the manual of Season7 3.2.
Q: Is my card adapter broken or is just my emulator software not up to date?
If the VideoCrypt decoder keeps the power supply of the card on and continues to talk to the PC, but the image is not descrambled, then the secret cryptographic function has been changed in some way by Sky and the PC software has to be updated. In this case, you have no problem with the adapter hardware and also the protocol timing of the PC software is ok.
If the decoder quickly deactivates the power supply again for the card after the adapter has been inserted and displays YOUR CARD IS INVALID, then either you have a defect in the adapter, or the timing of the card emulation software on the PC is not correctly adjusted. Changes in the encryption process cannot produce this effect.
Q: I am very interested in encryption systems and smartcard reverse engineering. What can I read to get familiar with the basics?
Pay-TV conditional access systems like VideoCrypt, VideoGuard, EuroCrypt, Irdeto, Nagra, etc. are all applications of cryptography. It is extremely helpful in understanding how these systems work if you make yourself familiar with the basic principles of cryptogryphy. The standard introductory textbooks in the field are:
Schneier's book is the most accessible one for non-academic readers, Menezes and Stinson are somewhat better suited for readers with a bit of a background in mathematics (e.g., computer science undergraduate students).
You should also make yourself familiar with the basics of electronics, and my favourite book here is:
A good general book about the basics of smartcards is
If you are interested in smartcard chip reverse engineering, then you best get started by reading
Kömmerling/Kuhn is the most detailed publically available summary of the tools and techniques that have in the past been used successfully by TV hackers to extract software from smartcards. Weste/Eshraghian is an excellent introductory textbook into the semicondoctor technology used by smartcard processors. Beck is an excellent hands-on chemistry cook-book with recipies for depackaging and delayering chips.
A book that describes many of the past hacks on European conditional access systems is: