Super encrypted storage and retrieval of media programs in a hard-paired receiver and storage device

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DESCRIPTION

Super encrypted storage and recovery of media programs on peer receiver and storage device.

The present invention relates to systems and methods for providing video program material to subscribers, and in particular to a method and system for safely storing or saving and reproducing media programs.

In the past, there has been a growing interest in allowing cable and satellite television subscribers to record broadcast media for later viewing. This capability, hereinafter referred to as personal video recording (hereinafter PVR), can be used to provide video on demand services (hereinafter VOD), or simply to allow the subscriber storing or saving media programs for repetitive viewing and / or archiving purposes.

In previous years, video cassette recorders (hereinafter VCRs) have been used for such personal video recording. However, recently, hard drives, similar to those used in personal computers, have been used to store or save media programs for later viewing. Unlike VCRs, such devices typically do not include a tuner, and are instead attached to a cable box or satellite receiver. Also unlike VCRs, these devices are typically used to record digital content, not analog video. This difference is both advantageous and disadvantageous.

An advantage of such devices is that they allow long-term memory storage and multiple replay without substantial degradation. Another advantage is that they allow more precise playback functions for digital format, (hereinafter simply "trick play functions") such as fast forward and fast rewind. A disadvantage of such devices is that they are capable of making multi-generation copies of program material as well and without serious degradation. This raises the very real possibility that multi-generation copies of media programs will be produced and distributed without authorization. This possibility has resulted in some media providers being reluctant to allow their media shows to be recorded using such devices.

To ameliorate this problem, it is critical to provide your saved media programs with strong backup and copy control. Current devices do not scramble media programs before saving, nor do they save copy protection information. Instead, such devices write decrypted program content to the memory disk using a matched hardware scheme in which the hard disk controller and the hard disk itself are specifically paired with each other through a specific interface. Since the hard drive controller and the hard drive itself are essentially paired together, memory storage or playback will not work if the disc had to be removed and transferred to another player. The weakness of this security scheme is that it relies solely on paired hardware for security ... media programs stored on the hard drive itself are not encrypted.

Although it is presumably possible to simply store or save the data stream as received from the issuing entity for later reproduction, this technique has clear drawbacks. One such drawback is that it would provide hackers with a permanently recorded version of the encrypted data stream, thereby providing the hacker with information that can be used to perform detailed analysis of the data stream itself to determine encryption techniques and codes.

What is needed is a system and method for safely recording broadcast media programs (including impulse purchase pay-per-view programs) for limited-use playback at a later time. Such a system could be used to support video on demand (VOD) services, thereby allowing the subscriber to instantly purchase media programs and games from the apparatus that is placed on top of the television without worrying about the program start time. What is also needed is a system and method that does not require substantial changes to the subscriber's hardware, such as the integrated receiver / decoder (hereinafter IRD), or the conditional access module (hereinafter CAM) that is used to provide a key to decrypt the media program for presentation to subscribers.

US-A-5 912 969 describes a recording / reproducing apparatus for a digital video signal. The apparatus receives an encrypted video signal over a transmission line. The video signal has been encrypted by an encryptor on the transmission side. The received digital video signal is further encrypted by the encryptor of the recording / reproducing apparatus. Encryption is carried out based on specific identification information that is stored in memory in an identification information memory storage circuit. Specifically, the digital video signal is encrypted by a signal encryption circuit that uses pseudo-random pulses as an encryption key. The encryption key is also encrypted using the specific information of the specific information memory storage circuit as a key. The encrypted key is combined with the encrypted video data and stored in memory by the recording system encryptor.

EP-A-O989 557 relates to a recording / reproducing apparatus for digital video / audio data. The received digital video / audio data is first decrypted using a broadcast encryption key. The broadcast encryption key is obtained by decrypting control information received together with the encrypted audio / video data. The decrypted audio / video data is encrypted according to a content key.

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The content key is encrypted as well. The Kco encrypted audio / video data together with the encrypted content key is recorded by a video tape recorder (hereinafter VTR) on a recording medium.

Document EP-A-0 975 165 relates to a system for managing access to a copy of an encrypted digital data stream. Encryption keys are included in access right control messages (hereinafter ECM) that could be encrypted using a public key or removable electronic card. Before encryption takes place, the recorder adds a mark to each ECM as an indication to copy. Every time an encrypted data stream is copied, your ECM is re-encrypted one more time. This allows the electronic card to determine how many times the original film has been copied.

The object of the present invention is to provide a system and a method for storing or storing in memory and retrieving program material for subsequent reproduction.

This is achieved by the features of the independent claims.

The method comprises the steps of receiving a data stream comprising the encrypted program material in accordance with a first encryption key and with control data, the control data of which comprises the first encryption key and is encrypted; further encrypting the encrypted program material in accordance with a second encryption key; encrypting the second encryption key in accordance with a third encryption key to produce a fourth encryption key; storing or saving in memory the additionally encrypted program material and the control data and the fourth encryption key.

The apparatus comprises a tuner, for receiving a data stream comprising encrypted access control information and the encrypted program material according to a first encryption key, the access control information of which includes the first encryption key; a first encryption module, communicatively coupled to the tuner and communicatively coupled to a media memory storage device, to further encrypt the encrypted program material in accordance with a second encryption key and to encrypt the second encryption key encryption according to a third encryption key in order to produce a fourth encryption key; a first decryption module communicatively attachable to a media memory storage medium, to decrypt the fourth encryption key retrieved from the media storage device using the third encryption key to produce the second encryption key, and to decrypting the further encrypted program material recovered from the media program device to produce the encrypted program material; a conditional access module communicatively coupled to the first decryption module, to decrypt the encrypted access control information to produce the first encryption key; and a second decryption module, for decrypting the program material using the first encryption key.

These objects are achieved by the features specified in claims 1 and 10. Further advantageous embodiments of the present invention are specified in the dependent claims.

The present invention eliminates the problems associated with the proliferation of unauthorized digital copies of media programs through the use of a strong encryption method. Furthermore, the present invention ensures that the material stored in memory cannot be distributed, because such decryption of the material can only be satisfactorily performed by the encryption IRD. At the same time, the present invention can be implemented with minimal changes to the IRD, and without changes to the interface of the conditional access module (hereinafter CAM). The present invention also provides a basis for a development path to more advanced encryption / decryption techniques.

Brief description of the drawings

Referring now to the drawings, in which like reference numerals represent corresponding parts throughout:

Figure 1 is a diagram showing an overview of a video distribution system;

Figure 2 is a block diagram showing a typical uplink configuration showing how video program material is uplinked to a satellite for transmission to subscribers using a single transponder;

Figure 3A is a diagram of a representative data stream received from a satellite;

Figure 3B is a diagram illustrating the structure of a data packet;

Figure 4 is a block diagram illustrating a high-level block diagram of the IRD;

Figure 5 is a block diagram illustrating memory storage and retrieval of data from a data memory storage device; Y

Figure 6 is a diagram illustrating memory storage and retrieval of data from the data memory storage device in an alternative embodiment of the invention.

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Detailed description of the preferred embodiments

In the following description, reference is made to the accompanying drawings which form a part thereof, and which show, by way of illustration, various embodiments of the present invention. It is understood that other embodiments could be used and that structural changes could be made without departing from the scope of the present invention.

Video distribution system

Figure 1 is a diagram illustrating an assembly view of a video distribution system 100. The video distribution system 100 comprises a control center 102 in communication with an uplink center 104 through land or another link 114 and an integrated receiver / decoder (hereinafter IRD) 132 in a receiving station 130 through from a public switched telephone network (hereinafter (PSTN) or from another link 120. Control center 102 provides program material to uplink center 104, coordinates with receiving station 130 to offer subscribers 110 pay-per-view (PPV) program services, including billing and decryption in association with the programs. Of video.

Uplink center 104 receives program material and program control information from control center 102, and using an uplink antenna 106, transmits program material and program control information to satellite 108. Satellite 108 receives and processes this information, and transmits the video programs and control information to IRD 132 at receiving station 130 via downlink 118. IRD 132 receives this information using subscriber antenna 112 to which it is communicatively coupled.

Video distribution system 100 may comprise a plurality of satellites 108 in order to provide broader terrestrial coverage, provide additional channels, or provide additional bandwidth per channel. In one embodiment of the invention, each satellite comprises 16 transponders for receiving and transmitting program material and other control data from the uplink center 104 and providing it to subscribers 110. However, using data multiplexing and compression techniques the channel capacities are much higher. For example, two satellites 108 working together can receive and broadcast more than 150 conventional audio and video channels (other than high definition television, hereinafter HDTV) through 32 transponders.

Although the invention set forth herein will be described with reference to a satellite-based video distribution system 100, the present invention could also be implemented with broadcasting of program information based on terrestrial antennas, either by means of conventional broadcast, by cable, or by other means. Furthermore, the different functions assigned collectively between the control center 102 and the uplink center 104 described above can be reassigned as desired without departing from the intended scope of the present invention. Although the above has been described with respect to an embodiment where the program material downloaded to the subscriber is video (and audio) program material such as a movie, the above method can be used to download program material comprising also purely information or audio data.

Figure 2 is a block diagram showing a typical uplink configuration for a single satellite transponder 108, showing how video program material is uplinked to satellite 108 via control center 102 and hub. uplink 104. Figure 2 presents three video channels (which could be augmented respectively with one or more audio channels for high-fidelity music, soundtrack information, or a secondary audio program for transmitting foreign languages), and a data channel of a computer data source 206.

The video channels are provided by a video material program source 200A-200C (hereinafter collectively referred to as video source (or sources) 200). The data from each video program source 200 is supplied to an encoder 202A-202C (hereinafter collectively referred to as encoder (s) 200. Each of the encoders accepts a presentation timestamp (hereinafter PTS) from the controller 216. The PTS is a recycled binary code timestamp that is used to ensure that the video information is properly synchronized with the audio information. after encoding and decoding. A PTS timestamp is sent with each embedded segment of the encoded data from the Moving Picture Experts Group (hereinafter MPEG).

In one embodiment of the present invention, each encoder 202 is a second generation Moving Picture Experts Group (MPEG-2) encoder, but other decoders that implement other encoding techniques could also be used. The data channel can be subjected to a similar compression scheme by an encoder (not shown), but such compression is usually either unnecessary or performed by computer programs in the computer data source (e.g. , photographic data is typically compressed into tagged image files (hereinafter * .TIF) or * JPG files prior to transmission). After encoding by encoders 202, the signals are converted into data packets by a packer 204 A-204F (hereinafter referred to as packer (s) 204) in association with each source 200, 206-210.

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The data packets are assembled using an access clock reference (hereinafter SCR) 214, a control word (hereinafter CW) generated by the conditional access manager 208, and a system channel identifier generator 210 (in forward SCID) that establishes an association relationship of each of the data packets that are sent to the subscriber with a program channel. This information is transmitted to packers 204 for use in generating the data packets. These data packets are then multiplexed into serial data, encoded, modulated, and transmitted. A special packet known as a control word packet (hereinafter CWP) comprising control data including the control word (CW) and other data used in support of the provision of conditional access to program material is also encrypted. and it is transmitted.

Figure 3A is a diagram of a representative data stream. The first packet segment 302 comprises video channel 1 information (data originating from, for example, the first video program source 200A). The next packet segment 304 comprises computer data information that was obtained, for example, from computer data source 206. The next packet segment 306 comprises information from video channel 5 (from one of the video program sources 200), and the next packet segment includes information from video channel 1 (again, from the first source 200 A of video programs). Thus, the data stream comprises a series of packets from any one of the data sources in an order determined by controller 216. The data stream is encrypted by encryption module 218, modulated by modulator 220 (typically using a quadrature phase modulation scheme (hereinafter QPSK), and supplied to transmitter 222, which outputs the modulated data stream in a frequency bandwidth to the satellite through antenna 106.

Subscribers 110 receive media programs through a subscriber receiver or IRD 132. Using the SCID, IRD 132 reassembles the packets to regenerate program material for each of the channels. As depicted in Figure 3A, null-value packets created by the null-value packet modulus 312 could be inserted into the data stream if desired.

Figure 3B is a diagram of a data packet. Each data packet (eg 302-316) is 147 bytes long, and comprises a number of packet segments. The first packet segment 320 comprises two bytes of information containing the SCID and flags. The SCID is a unique 12-bit number that uniquely identifies the data channel of the data packet. The flags include 4 bits that are used to control if the packet is encrypted, and what key they should use to decrypt the packet. The second packet segment 322 is made up of a 4-bit packet type indicator and a 4-bit continuity counter. The packet type identifies the packet as one of the four data types (video, audio, data, or zero. When combined with the SCID, the packet type determines how the data packet will be used. The continuity counter is incremented once for each packet type and SCID. The next packet segment 324 comprises 127 bytes of payload data, which is a part of the video program provided by the video program source 200. The final packet segment 326 is the data required to perform forward error correction.

Media program encryption

Media programs are encrypted by encryption module 218 prior to transmission to ensure that they are received and viewed only by authorized subscribers. Each media program is encrypted according to an alphanumeric encryption key hereinafter referred to as a control word (CW). This can be accomplished by a variety of data encryption techniques, including the standard data encryption algorithm (DES) and the Rivest-Shamir-Adleman algorithm (hereinafter RSA).

To decrypt the media programs, the IRD 132 of the subscriber 110 must also have access to the CW. To maintain security, the CWs are not transmitted to the plaintext of the IRD 132. Instead, the CWs are encrypted prior to transmission to the subscriber's IRD 132. The encrypted CW is transmitted to the subscriber's IRD 132 in a control word (data) packet.

In one embodiment, the data contained in the CWP, including the CW, is encrypted and decrypted by means of the algorithm hereinafter referred to as the indecipherable input / output (I / O) algorithm.

An indecipherable I / O algorithm is an algorithm that is applied to an input data stream to produce an output data stream. Although the input data stream exclusively determines the output data stream, the selected algorithm is such that its characteristics cannot be deciphered from a comparison of even a large number of input and output data streams. The security of this algorithm can be further increased by adding additional functional elements that are not stationary (that is, that vary with time). When such an algorithm is provided with identical input streams, the output stream provided at a given point in time could be different than the output stream provided at another point in time.

As long as the encryption module 218 and the IRD 132 share the same indecipherable I / O algorithm, the IRD 132 can decrypt the information contained in the CWP to retrieve the CW. Then, using CW, IRD 132 can decrypt the media program so that it can be presented to subscriber 110.

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To further deter hackers, the control data needed to decrypt and assemble data packets in viewable media programs could be time-varying (the validity of the control data contained in a CWP to decode a program particular media varies over time). This can be implemented in a variety of modalities.

For example, since each CWP is associated with a SCID for each media program, the SCID associated with each CWP could vary over time.

Another way to implement time-varying control data is to establish a timestamp association relationship with the received data stream and with the CWP control data. In this case, successful decoding of the CWP to produce the CW would require the appropriate relationship between the timestamps for the data stream and the control data contained in the CWP. This relationship can be defined, for example, by changing the decryption scheme used to generate the CW of the CWP in accordance with the received timestamp for the data stream. In this case, if the timestamp of the received data stream does not match the expected value, the wrong decryption scheme will be selected and the appropriate CW (for decrypting the program material) will not be produced. However, if the timestamp of the received data stream matches the expected value, the appropriate decryption scheme will be selected, and the CWP decryption scheme will produce the appropriate CW.

Request for pay-per-view services

The data required to receive pay-per-view media programs (hereinafter PPV) was stored in the CWP and in another data package known as the purchase information package (hereinafter PIP). Both the CWP and the PIP are broadcast to the subscriber through the video distribution system 100 in real time. As described below, IRD 132 uses PIP to retrieve PPV media programs.

In general, PPV services may include operator-assisted pay-per-vision services (hereinafter OPPV) and impulse pay-per-view services (hereinafter IPPV). When requesting OPPV services, subscriber 110 must decide in advance that he wishes to have access to a particular media program. Subscriber 110 then calls an entity such as control center 102, and requests access to the media program. When requesting impulse pay-per-view (IPPV) services, subscriber 110, while viewing the program guide, moves the cursor over the viewer channel in association with the desired media program, and selects "enter ”. Once the decision and rights to purchase a PPV program have been confirmed (for example, by checking for channel locks, capacity limits, and purchase limits), a Purchase Information Package (PIP) is received and is stored in conditional access module 406 (described in detail later). The conditional access module 406 establishes an association relationship between the information contained in the CWP and the PIP, and uses the PIP in conjunction with the CWP to verify that subscriber 110 should be provided access to the media program and to decrypt the program. media.

However, the request for PPV media programs in advance using the PIP is limited, because the PIP is broadcast up to 24 hours before the media program itself is broadcast. Since the PIP is broadcast in real time, the IRD 132 does not acquire the PIP until the subscriber 110 actually requests the purchase of the PPV media program.

Subscriber reception and decryption of media programs

Figure 4 is a simplified block diagram of an IRD 132. The IRD 132 receives and decrypts the media program broadcast by the video distribution system 100. These media programs are sent as data streams to the IRD 132 in real time. , and could include, for example, video, audio, or data services.

IRD 132 is communicatively coupled to conditional access module 406 (CAM). The CAM 406 is typically implemented in an electronic card or similar device, which is provided to the subscriber 110 to insert it into the IRD 132. The CAM 406 has an interface with a conditional access verifier (hereinafter CAV) 408 that performs at least some of the functions necessary to verify that the subscriber 110 has the right to access the media programs. The CAV 408 is communicatively coupled to a metadata analysis module (hereinafter MAM) 411. Using the information contained in the metadata table (for example, Table 1 described below), the MAM acts as a watchdog for gate to determine whether the stored media programs will be decrypted and presented to the subscriber 110. This is done by comparing the metadata values ​​and the measured or accumulated values. The CAV 408 and MAM 411 may be implemented as separate decryptor / demultiplexer / transport modules 412 and microcontroller and memory 414 as shown, or they could be implemented by means of software instructions stored in memory and executed by microcontroller 414.

The IRD 132 comprises a tuner 132, a transport and demultiplexing module (hereinafter TDM) 412, which operates under control of a microcontroller and memory in association relationship 414, a source decoder 416 and a random access memory (hereinafter RAM) 418 communicatively coupled, and a user input / output device (hereinafter I / O) to accept execution orders from subscriber 110 and to provide output information to the subscriber.

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The tuner receives the data packets from the video distribution system and supplies the packets to the TDM 412. Using the SCIDs in association with each media program, the TDM 412 reassembles the data packets according to the channel selected by the subscriber 110, and decrypts the media programs using the CW key. The TDM 412 can be implemented by a single secure chip, and is communicatively coupled to a microcontroller and memory 414.

Once the programs have been decrypted, they are provided to the source decoder 416 which decodes the media program data in accordance with MPEG or JPEG standards as appropriate. The decoded media program is then sent to the digital / analog converter (hereinafter D / A converter) (if necessary) and sent to external interfaces 404 which may include a media program display device such as a television, an audio system, or a computer. Source decoder 416 makes use of communicatively coupled RAM 418 to perform these functions.

The CW key is obtained from the CWP using the CAV 408 and the CAM 406. The TDM 412 provides the CWP to the CAM 406 through the CAV 408. The CAM 406 uses the indecipherable I / O algorithm to generate the CW, which is it sends back to TDM 412. TDM 412 uses CW to decrypt media programs. In most IRD 132s, the CAV 408 and CAM 406 are capable of decrypting one video / audio / data media program at a time.

As described above, to deter would-be hackers, the control data contained in the CWP that is used to decode a particular media program could vary over time such that it only produces the appropriate CW when applied to a media program that has the appropriate timestamp.In this case, CAM 406 may select and / or control the decryption scheme (eg, the I / O indecipherable algorithm) in accordance with the timestamp in association with the data stream carried by the media program. If the media program is sufficiently disassociated in time, the wrong decryption scheme will be used, and the proper CW will not be produced to decode the media program.

Further details regarding the encryption and decryption of media programs can be found in copending and commonly assigned US Patent Application Serial No. 09 / 491,959.

Storage and recovery of media programs in encrypted form

Figure 5 is a diagram showing the steps of an exemplary method used to practice an embodiment of the present invention. A data stream is provided by subscriber antenna 112 and received by tuner 410 and TDM 412, as shown in block 502. The data stream includes a plurality of data packets including data packets with program material 504 encrypted in accordance with a first encryption key (CW key 538) and access control information manifested within one. or more control word packets (CWP 506). The control word packets 506 include an encrypted version of the CW key 538. The data stream could also include metadata that has replay rights. Reproduction rights are parameters necessary to control the reproduction of IPPV or pay-per-view services.

The encrypted program material 504 (designated as encrypted V / A / D in Figure 5 to indicate that the program material may include audio video data, or other data) is then sent to a first encryption module 552. The first encryption module 552 includes a memory storage encryption module 508 and a key encryption module 516 (hereinafter KEM). The copy protection encryption module 508 (CP) encrypts the encrypted program material 504 (thus further encrypting the encrypted program material 504) and the CWP 506 with a copy protection key (CP) 514. In a In this embodiment, this is done by means of a triple chaining of 56-bit encrypted blocks (hereinafter CBC of data encryption standard (hereinafter DES)). Encryption with the RSA algorithm could also be used, but triple DES is temporarily more efficient, and therefore preferred.

In one embodiment, the CP key 514 is obtained using a CP generation module 546 of the properties of the reproduction rights and other metadata contained in the broadcast stream. Depending on the metadata, CP key 514 could also be time-varying with broadcast program material. In another embodiment, the CP key could be augmented with at least a portion of the metadata before being encrypted with the cashier key 518 in the KEM 516 and stored on the media storage device as the encrypted CP key 520. In this embodiment, when the encrypted CP key 520 is decrypted, both the CP key and related metadata are produced. The metadata can then be used to verify and / or control the playback of program material. The CP key 514 could also be generated internally by the IRD 132 without the metadata.

The key encryption module 516 also encrypts the CP key 514 with the cash key 518 to produce an encrypted CP key 520. In one embodiment, box key 518 is stored within IRD 132. For example, box key 518 could be an internal electronic serial number (ESN) of an integrated circuit that implements some or all of the TDM functions. 412 (hereinafter "transport chip"). Incorporating the ESN into the encryption key ensures that only the IRD 132 that stored the encrypted information on the program storage device can successfully decrypt the data stream.

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The further encrypted program material 510, the encrypted CWP 512, and the encrypted CP key 520 are then stored 522 in the media memory storage device 524. The media memory storage device 524 is typically a hard disk, but could be any device with sufficient capacity and access time to support recording and / or reproducing operations of the data stored therein.

When the subscriber 110 decides to play the stored media programs, an appropriate user input is provided at the user I / O device 420. The user input could comprise a play play command, a fast forward play command, a reverse play command, a fast play or fast play back command run, or a pause play command. . In response to user input, the saved data is retrieved from the media storage device 524. This data includes the further encrypted program material 510, the encrypted CWP 512, and the encrypted CP key 520. The encrypted CP key 520 is decrypted using the box key 518 to produce the CP key 514. This CP key 514 is used to decrypt further encrypted media program material 510 and encrypted CWP 512 to produce encrypted media program 504 and CWP 506, respectively. The CWP 506 is supplied to the CAM 406.

The IPPV control module 532 determines whether the requested media program is a PPV program (IPPV or OPPV). If it is, subscriber 110 is informed that the selected media program is a PPV program. If subscriber 110 chooses to receive the PPV program, a PPV request is accepted, and the purchase history module 534 collects and records the information related to the requested program material so that subscriber 110 can be billed for viewing the program. media program. In one embodiment, the PPV request is compared with the copyright information contained in the metadata to determine whether the program material that is the subject of the PPV request should be decrypted and provided. For example, the copyright metadata could be used to indicate that the program could be viewed for a specific period of time, or for a particular number of screenings.

The CWP 506 is then supplied to the CW extraction module 536, which produces the CW key 538. In one embodiment, this is done on CAM 506 by applying the indecipherable I / O algorithm noted above. Using the CW key 538, the encrypted program material 504 is decrypted to produce a plaintext version of the media program 542.

Using the above scheme, the encrypted program material and the CWP 506 must be tracked and correlated during decryption by the IRD 132. This can be done by correlation across timestamps, and / or chunks of MPEG1 and P. As each program playback requires the CP decryption process (via CP 538 key) and the CA decryption process (via CW), decryption could be slowed down enough to cause delay or deletion of the video. during trick play functions. This problem could be minimized by setting aside enough staging memory to handle the decoded video.

After proper processing (i.e. MPEG and / or JPEG decoding, decompression, conversion to an analog signal, etc.), the media program is provided to an external interface device 404, which could include such a display device. as a display screen 544.

In one embodiment of the present invention, the data stream received at IRD 132 further comprises metadata including data for controlling reproduction rights and copy protection. This metadata could be encrypted by the CP encryption module 552 and stored or saved in the media memory storage device 524 for decryption and later use when a request is received to view the media program. Alternatively, the metadata can be encrypted and broadcast on the data stream in real time for all PPV-enabled media programs, thereby obviating the need to store or save the information in the media memory storage device 524.

As described above, the relationship between the CWP 506 and the encrypted media program could be variable over time. However, in the nominal case described above, since both the CWP 506 and the program material 504 encrypted in association with the same timestamps are saved, playback of the saved material can be performed without modification to the indications of time or CWP 506. However, if time-limited reproduction rights are desired, the time stamps or in relation to association with the CWP 506 or the CWP 506 itself could be modified before being stored in memory.

Although the foregoing has been described with respect to a plurality of encryption modules (eg, modules 508 and 516) and decryption modules (eg, modules 528 and 530), the present invention can be implemented with a single module of encryption, a single decryption module, or a single encryption / decryption module. In one embodiment of the present invention, the operations performed by modules 508, 516, 528, and 530, are performed on a single integrated circuit device such as a transport chip.

Figure 6 is a diagram showing an alternative embodiment of the present invention, in which the CWP 506 is saved to the media storage device without encryption by the CP key 514. In this embodiment, the CWP 506 is read from the media memory storage device 524 and provided to the CAM 406, and does not need to be decrypted using the CP key 514. An advantage of this embodiment is that it requires fewer encryption and decryption operations, thereby allowing program materials to be saved and retrieved more quickly from the computer.

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Conclution

The present invention describes encryption and decryption functions that increase the security of data stored on the hard disk to further encrypt (with a CP or copy protection key) already encrypted program material comprising an MPEG stream of data. / video / audio prior to memory storage. These encryption and decryption functions are provided by IRD 132, preferably within the transport chip. Since the broadcast data stream is not decrypted prior to storage on the media memory storage device, but rather is further encrypted, a plaintext version is not exposed to possible compromise prior to storage on the device. memory storage media. Furthermore, since the encrypted broadcast stream is further encrypted prior to memory storage, the encrypted broadcast stream is not available to would-be hackers to discuss how to try to break the broadcast stream's encryption scheme.

In one embodiment, metadata is included in the broadcast data stream to IRD 132. This metadata includes playback rights and other parameters necessary to control playback of the media program. These reproduction rights included in this metadata and / or the airtime of the program material can be used to obtain the CP key 514 which is used to further encrypt the (already) encrypted program material.

The program material requested for storage on the media memory storage device includes the additionally encrypted version of the encrypted program material and the CWP 506. This additionally encrypted data is not decrypted until the user begins playback of the device's program. memory storage media.

Once playback has started, the further encrypted data and the encrypted CWP 506 is decrypted using the CP key 514. The decrypted CWP 506 is provided to the CAM 406. The CAM 406 decrypts the CWP 506, and provides the resulting CW 538 to a broadcast decryption module to decrypt the encrypted program material.

The present invention protects the data stored in the media memory storage device against hackers, and does not expose the program material in a decrypted form until the viewer has requested (and paid for) the program material. Furthermore, this is done without introducing additional functions of the CAM 406. By using the metadata to obtain a CP key 514 to encrypt the encrypted program data and the CAM 406, the present invention provides additional security, while providing a development path enables more advanced pay-per-view features. view. The foregoing discussion of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described. Many modifications and variations are possible in light of the above description. For example, the encryption functions described herein could be performed by separate encryption / decryption modules, or a single multipurpose encryption / decryption module could be used to perform the encryption / decryption functions of many separate modules.

The foregoing discussion of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described. Many modifications and variations are possible in light of the above description. It is intended that the scope of the invention is not limited by this detailed description, but rather by the claims which are appended thereto. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. The invention is based on the claims which are appended hereunder.