Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Particular node for directing data and applying cryptography
Reexamination Certificate
1999-10-26
2002-12-24
Peeso, Thomas R. (Department: 2132)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Particular node for directing data and applying cryptography
C713S168000, C713S152000, C713S152000
Reexamination Certificate
active
06499103
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to apparatus and methods for displaying or making sensible a symbol or a mark, in particular in cases where the symbol or mark is associated with an encoded message.
BACKGROUND OF THE INVENTION
Systems for displaying a symbol on a television display are well known in the art.
U.S. Pat. No. 3,928,845 to Clark describes a character generator system suitable for use in a television broadcast controller.
U.S. Pat. No. 5,253,067 to Chaney et al describes a system to allow a user to select preprogrammed labels for widely used television networks.
Japanese published application 57-65974 describes a character multiplex broadcast TV receiver having a memory for displaying a symbolic pattern representing a concealed display.
Systems for scrambling a television transmission are also well known in the art. The terms “scramble” and “encode”, in their various grammatical forms, are used interchangeably throughout the present specification and claims to refer to any method suitable for scrambling or encoding a television transmission. The terms “descramble” and “decode”, in their various grammatical forms, are similarly used interchangeably throughout the present specification and claims to refer to any method suitable for rendering a scrambled or encoded television transmission suitable for viewing. Many such methods are known in the art; examples of methods in wide use include “cut-and-rotate”, described, for example, in U.S. Pat. No. 4,070,693 to Shutterly, and DES encryption, as described below.
One system for scrambling a television data stream is described in U.S. Pat. Nos. 5,282,249 and 5,481,609, both to Cohen et al. Scrambled television transmissions described in the Cohen et al. patents include both scrambled data representing television signals and coded control messages, also known in the art as ECMs. The ECMs of Cohen et al. include, in a coded form, data necessary for generating a control word (CW) which may be used to descramble the scrambled data representing television signals.
Data necessary for generating a control word is known in the prior art to take many different forms and may include, in general, at least any of the following: a control word; an encrypted control word which is intended to be decrypted before use, and a seed to a generating function such as, for example, a one-way function which generates the control word upon input of the seed. Throughout the present specification and claims the terms “control word generating information” and “CW generating information” are used interchangeably to designate data necessary for generating a control word in any appropriate form, as described above.
While the two patents to Cohen et al. describe an analog system, that is, a system in which analog television data streams are broadcast to television sets, it is appreciated that similar ECM methods may also be used for digital television data streams. Generally, the scrambling techniques used for scrambling analog television signals such as, for example, the well known “cut-and-rotate” technique, are chosen for their applicability to analog signals. In scrambling of digital television signals other scrambling techniques, well-known in the art, are used, the techniques being more appropriate to digital signals such as, for example, applying the well-known DES algorithm to the digital television signals.
A typical prior art system for scrambling and descrambling a television transmission is shown in FIG.
1
. In the prior art system of
FIG. 1
, a removable security element such as a smart card is used to derive a CW from CW generating information included in an ECM and to supply the CW to a decoder for use in descrambling a scrambled television signal.
Methods of transmitting a scrambled digital signal, including ECMs, are well known. The prior art system of
FIG. 1
may use a composite signal, that is, an analog or digital signal including more than one component, typically including both a scrambled television signal and ECMs. Prior art references which discuss examples of this type of signal include the following: DVB ETR289, “Digital Video Broadcasting (DVB): Support for use of scrambling and conditional access (CA) within digital broadcasting systems”; and DVB SIM061, “Technical specification of DVB-Simulcrypt”, Apr. 1 1997.
Other documents relating to broadcasting of digital information include the DVB Specification for Data Broadcasting, document SI-DAT 360 (TM 1779), Feb. 12 1997; and ATSC Digital Television Standard, document A54, October 1995 and subsequent editions.
Other methods of transmitting a scrambled digital signal, particularly useful in a case where the signal includes sub-signals encoded according to various different methods, are described in “Common Interface Specification for Conditional Access and other Digital Video Broadcasting Decoder Applications”, DVB document A017, May 1996 and subsequent editions; and in “Common Interface Specification for Conditional Access and other Digital Video Broadcasting Decoder Applications”, CENELEC EN0221:1997.
The disclosures of all references mentioned above and throughout the present specification are hereby incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved apparatus and methods for displaying or making sensible a symbol or a mark, in particular in cases where the symbol or mark is associated with an encoded message. In a preferred embodiment of the present invention, a symbol or mark is displayed on a display, particularly on a television display. It is appreciated that a mark, such as a trademark, may be sensible to a sense other than vision, and that the present invention is not limited in its applicability to visible marks.
The apparatus and method of the present invention are particularly applicable to encoded data systems, such as encoded data storage systems and encoded data transmission systems. One particularly well-known example of such systems is encoded television systems. Throughout the present specification and claims, encoded television systems are often discussed by way of example, without limiting the generality of the present invention. Other typical applications of the present invention include, but are not limited to the following: other encoded broadcast systems, such as encoded data broadcast systems; and non-broadcast systems, such as systems for playing back a recording, particularly systems for playing back an encoded recording.
In encoded television systems, it may be desirable to cause elements of the system which are responsible for decoding to display a symbol on a television display at a particular time. For example, it may be desirable to display a symbol, such as a trademark, associated with a vendor or with a product or service supplied by a vendor at the time of a sale or offer for sale of a product or service. In the present specification and claims, the terms “symbol”, “mark”, and “trademark” are used interchangeably to refer to any sensible emblem, token, or sign, particularly of the kinds suitable for use as a trademark.
While the various embodiments of the present invention are generally described below with reference to display of a symbol or mark, it is appreciated that the symbol or mark may be provided as an output and not directly displayed, and the symbol may or may not be further processed, including processing for display, after being produced by the present invention.
It may further be desirable to associate such a symbol with the decoding of encoded television signals in such a way that the decoding equipment is required to supply the symbol for display in order to ensure proper decoding of the encoded signal.
There is thus provided in accordance with a preferred embodiment of the present invention a symbol-display subscriber unit for use with a broadcast system, the broadcast system including a headend and a network operative to transmit a composite signal from the headend to a multiplicity of subscriber units, the composite signal including an encoded
Itkis Gene
Sella Yaron
Sered Yishai
Tsuria Yossef
NDS Limited
Peeso Thomas R.
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