Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Particular communication authentication technique
Reexamination Certificate
2000-03-24
2004-11-02
Sheikh, Ayaz (Department: 2136)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Particular communication authentication technique
C713S172000, C713S152000, C705S055000, C705S056000, C705S057000
Reexamination Certificate
active
06813709
ABSTRACT:
The present invention relates to a method and apparatus for protection of recorded digital data, for example protection of audio and/or visual data as recorded on compact disks, digital video disks or other similar supports.
The introduction of digital technology in the audiovisual field has brought considerable advantages to the consumer in comparison with analog technologies, notably in relation to the quality of reproduction of sound and image and the durability of the support medium. The compact disk has all but replaced traditional vinyl records and a similar trend is expected with the introduction of new digital products aimed at the multimedia and home entertainment markets generally. notably the digital video disk.
A particular problem associated with digitally recorded data lies in its ease of reproduction and the possibilities for piracy that arise therefrom. A single digital recording may be used to make any number of perfect copies without any degradation in the quality of the sound or image. This problem is serious, particularly with the advent of recordable digital products such as the minidisk or DAT, and the reluctance of entertainment companies to license copyright works whilst this problem remains has acted as a break on the introduction into the market of new media products.
At present, the only practically available solution against unauthorized reproduction of copyright works has been a legal one, and a number of countries in Europe and elsewhere have introduced anti-piracy legislation to combat the increasing number of pirate films, CDs etc being brought onto the market. For obvious reasons, a legal solution is less than optimal from the point of view of preventative action.
Technological anti-copying solutions proposed to date for audiovisual works have been extremely basic, relying for example on the idea of using some form of digital <<handshake>> between the reader and support medium so as to verify the origin of the the recording. Such protection is, however, only effective against only the most low level of copying activity, since the handshake signal is not protected in any way and may be easily read and reproduced so as to convert an unauthorised copy into an apparently authorised and readable copy.
Computer systems using secret keys stored in a smart card to control access to encrypted computer disk data are known, for example, from U.S. Pat. No. 5,191,611. Such systems possess the disadvantage that the reader needs to be provided with considerable processing and memory capabilities in order to decrypt and store the recorded encrypted blocks of data. As will be understood, such systems are generally inconvenient when used to protect computer data and are even more unsuitable for application in the audiovisual domain, where a reader device typically has a much smaller capacity to process and store data in comparison with a computer, but where a real-time flow of data needs nevertheless to be maintained.
The aim of the present invention is to overcome the disadvantages associated with the prior art techniques and to provide an efficient technological solution against the unauthorised reproduction of digitally recorded copyright works, particularly in relation to audiovisual works.
According to the present invention there is provided a method of restricting access to recorded digital data on a digital support medium using an integrated circuit containing a first decryption key characterized in encrypting with a corresponding encryption key one or more elements of the volume descripter of the support medium, recording the encrypted volume descripter elements together with non-encrypted data on the support medium and, when accessing the support medium, using the integrated circuit decryption key to decrypt the encrypted elements of the volume descripter and to supply a reader with these elements so as to permit the reading and/or writing of non-encrypted data on the support medium.
For digital support mediums, such as CDs, CD ROMs, etc., each recording has associated therewith an introduction or header in the form of a volume descriptor which sets out basic information regarding the storage layout and points of access of digital information in the medium, the amount of data stored in the medium, the date of creation of the support medium etc. This information, which occupies only a small amount of memory, is nevertheless essential to the reading of the recording and, without this information the reader cannot access the recorded data.
By encrypting this information and storing the decryption key in an integrated circuit associated with the support medium, the present invention protects against unauthorised copying of the recording, since the reader will not be able to access the stored data without the decrypted elements of the volume descripter and since the key necessary to do this is held by the integrated circuit, which is of course resistant to copying. Even if the stored non-encrypted data is copied, the resulting copy will be unreadable since the volume descripter will only be present in an incomplete or entirely encrypted form. The decryption of the volume elements may be carried out inside the integrated circuit, such that the key is never made freely available.
Unlike the prior art technique used for protecting computer data, only the volume descripter or header data is encrypted/decrypted, avoiding the need to carry out cryptographic operations on the entire volume of stored data. As will be understood, this is particularly advantageous where the invention is to be applied to the field of audiovisual devices, where the processing and memory capacity of a reader may be relatively small.
In one embodiment, the integrated circuit is embedded in a smart card associated with the support medium, the smart card acting to decrypt the encrypted volume elements and to pass these to the reader so as to permit reading and/or writing of the recorded non-encrypted data.
In this context, a smart card provides a secure and durable means for stocking the key necessary for decryption of the volume descripter elements. Equally, the cost of production of such a card is relatively small in comparison with, for example, the price of the recording itself.
In this application the term <<smart card>> is used to mean any conventional chip-based card device possessing, for example, microprocessor or EEPROM memory for stocking the key. Also included in this term are PCMCIA cards and other portable chip carrying cards or devices having alternative physical forms, such as the key-shaped devices often used in TV decoder systems.
Whilst providing a particularly convenient way of housing the integrated circuit or <<chip>> used in the invention, a smart card is not the only solution available. For example, in one realisation, the key is stored in an integrated circuit embedded in the housing of the digital support medium.
Incorporation of a microprocessor within the housing of the support medium is a known technique and has been suggested, for example, in the case of DVHS cassettes where a set of metallic contacts may be provided on an exterior surface of the cassette housing, the contacts leading to an integrated circuit or chip in the interior of the housing. These contacts may be engaged by a corresponding set of contacts in the receptacle of the recorder to enable communication between the integrated circuit and the video recorder.
Such a solution avoids the need for the provision of a smart card or the like in conjunction with the recording and is thus inherently simpler from the point of view of the consumer. The need to include, for example, a smart card slot in the digital reader is also avoided, although the cost of production of the recording medium will of course increase to incorporate the introduction of an integrated circuit in the housing, as may the costs of the elements of the reader used to read the support
In one embodiment the key for encrypting and/or decrypting the volume descripter elements comprises a key diversif
Baum Ronald
Canal+ Societe Anonyme
Osha & May L.L.P.
Sheikh Ayaz
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