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`US006985586B2
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`(12) United States Patent
`Ififl
`
`(10) Patent N0.:
`
`(45) Date of Patent:
`
`US 6,985,586 B2
`Jan. 10, 2006
`
`(54) DISTRIBUTED INFORMATION AND
`STORAGE SYSTEM
`
`(75)
`
`Inventor: Michael John Hill, Coppet (CH)
`
`(73) Assignee: Nagracard S.A.,
`Cheseaux-sur-Lausanne (CH)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 956 days.
`
`(21) Appl. No.: 09/796,261
`
`(22)
`
`Filed:
`
`Feb. 28, 2001
`
`(65)
`
`Prior Publication Data
`US 2002/0080962 A1 Jun. 27, 2002
`
`(30)
`
`Foreign Application Priority Data
`
`Dec. 22, 2000
`
`(CH) ............................................ .. 2518/00
`
`(51)
`
`Int. Cl.
`G06F 17/00
`
`(2006.01)
`
`W0
`
`WO 00/11871
`
`3/2000
`
`OTHER PUBLICATIONS
`
`A stream tapping protocol with partial preloading Paris,
`J.—F.; Modeling, Analysis and Simulation of Computer and
`Telecommunication Systems, 2001. Proceedings. Ninth
`International. *
`
`Improving Video—on—demand server efficiency through
`stream tapping Carter, S.W.; Long, D.D.E.; Computer Com-
`munications and Networks, 1997. Proceedings, Sixth Inter-
`national Conference on , Sep. 22-25, 1997.*
`Implementation of a terrestrial return channel for digital
`interactive video broadcast Allan, R.; Taylor, C.; Broadcast-
`ing Convention, 1997. International , Sep. 12-16, 1997.*
`Chang, Y —H., et al.: An Open—Systems Approach to Video
`on Demand, IEEE Communications Magazine, vol. 32, No.
`5, 68-80, May 1, 1994.
`
`* cited by examiner
`
`Primary Examiner—David Jung
`(74) Attorney, Agent, or Firm—Clifford W. Browning;
`Woodard, Emhardt, Moriarty, McNett & Henry LLP
`
`(57)
`
`ABSTRACT
`
`(52) U.S. Cl.
`
`......................... .. 380/231; 380/200; 725/2;
`725/4
`
`The aim of the present invention is to propose a method that
`allows the reduction of the bandwidth needs in a structure
`
`(58) Field of Classification Search ............... .. 380/200,
`380/231-234, 210-212, 255-264; 725/1-5,
`725/105-134; 370/200-205; 213/150-154
`See application file for complete search history.
`
`that implements an operating center and a plurality of user
`units, ensuring the availability for the final user, of a product
`amongst a vast choice and being able to be downloaded by
`said user in a short period of time.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,341,425 A
`5,898,456 A
`
`8/1994 Wasilewski
`4/1999 Wahl
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`EP
`
`0672991 A2
`0843449 A2
`0884669 A2
`
`9/1995
`5/1998
`12/1998
`
`This aim is achieved by a system that implements at least
`one operating center that has a great number of products, a
`plurality of user units comprising security and storage
`means, characterized in that the link between at least one
`group of user units is of the bidirectional type and that the
`operating center comprises means for the transfer of a
`product that is stored in the storage means of a user unit to
`another user unit.
`
`14 Claims, 3 Drawing Sheets
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`9' ‘*1
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`U.S. Patent
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`Jan. 10, 2006
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`Sheet 1 on
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`US 6,985,586 B2
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`CCS
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`U.S. Patent
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`Jan. 10, 2006
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`Sheet 2 on
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`US 6,985,586 B2
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`(X)CA m Fig, 2
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`OOCA
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`(CA)Kb
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`Fig_ 3
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`Fig_ 4
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`000A
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`IE3
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`U.S. Patent
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`Jan. 10, 2006
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`Sheet 3 of3
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`US 6,985,586 B2
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`BD
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`BDB
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`CC1..........-......»...«..»....m...m....-....u-
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`DC1<3
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`Fig.6
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`US 6,985,586 B2
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`1
`DISTRIBUTED INFORMATION AND
`STORAGE SYSTEM
`
`This invention concerns a system and a method of
`management of distributed data, particularly in a system that
`involves an operating center and a plurality of user units.
`
`BACKGROUND OF THE INVENTION
`
`In a data distribution system from a central site to a great
`number of users,
`the organisers of such a resource are
`regularly occupied with two matters. The first concerns the
`security of the data, that is, to ensure that the targeted user
`is the only one to receive the requested data, and for his/her
`use only.
`The second matter is the capacity of the distribution
`means, that is,
`the galvanic or optic lines, cable, or the
`radio-relay network.
`The operating center has an important data base that
`contains the products offered to the users either subject to
`payment or free of charge. According to the recent structures
`of this type of center only one part of these products are
`stored locally, the other products being stored by the pro-
`ducer of these data and linked to the operating center by high
`speed communication means.
`The user sends a request to the operating center compris-
`ing his/her identity, address, and the desired product.
`The operating center determines the acceptability of this
`request, particularly according to the payment methods of
`this user. These methods can be by subscription, with
`unlimited access to the products, upon presentation of bills,
`payment by credit card, or pre-payment.
`The product is sent in encrypted form with a user’s key,
`that is, according to a key that is contained in a security
`module at the user’s location.
`
`This type of service is used for hiring video films through
`pay television. In this use the subscriber has a security
`module connected to his/her decoder that processes the
`encrypted data and sends the decryption keys to the decoder.
`This security module also administers credit information.
`This system works today with the so called form NVOD
`(Near Video On Demand) and VOD.
`In the first case
`(NVOD) the proposed product for buying is sent loopback
`to all the users, sometimes through several channels simul-
`taneously with a time delay. The buyer then can only buy
`this specific product and will wait for the next emission to
`start the visual display. An embodiment of this mode con-
`sists in sending several products during the time of inactivity
`of the system (generally in the morning), said products being
`stored in the mass memory of the decoder. The products thus
`memorised are then proposed to the user for buying and can
`be visualised at any given moment.
`In either of these embodiments the number of proposed
`products is lower than ten, taking into account the transmis-
`sion and storage possibilities of a product.
`The second case, which is particularly interesting, pro-
`poses supplying the product of your choice amongst a very
`important catalogue of products. Each user can then choose
`from this catalogue and the operating center sends him/her
`the desired product. This is only possible in a restricted
`environment with very important transmission capacities.
`The implementation on a large scale of such a system has
`very quickly collided with the bandwidth limits of the
`transmission means. Just to remember, it is reminded here
`that the transmission of a 2 hour film represents 1 gigabyte
`of high compressed data.
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`SUMMARY OF THE INVENTION
`
`The aim of this invention is to propose a system and a
`method that allows the reduction of the bandwidth needs
`
`ensuring a better availability for the final user of a product
`amongst a vast choice, and being said user able to receive
`this product in a short period of time without compromising
`the quality or the time to obtain this product.
`This aim is achieved by a system that implements at least
`one operating center that has a great number of products, of
`a plurality of user units comprising security and storage
`means, characterised in that the link between at least one
`group of user units is of the bidirectional type and that the
`operating center comprises means for transferring a product
`that is stored in the storage means of one user unit to another
`user unit.
`
`In this way, thanks to this system, the operating center
`uses the storage means of the user units as intermediate
`storage means. It is enough to send the product only once to
`a user amongst a group of users so that each request of the
`same product coming from this group of users does not
`cause the transmission from the operating center, but the unit
`containing the desired product will take the relays locally to
`transmit it to the final user.
`
`This invention includes also a method for the optimisation
`of the transmission on demand towards a final user, method
`consisting in:
`receiving by the operating center of a transmission request
`of a product from a first user unit connected to a local
`bi-directional network,
`determining if the requested product is already in a second
`user unit connected to the same local network,
`if the negative event,
`transmitting from the operating
`center to the first user unit and storing the product in
`said first user unit,
`if the positive event, ordering the transfer of the product
`from the second unit to the first user unit,
`transmitting by the operating center the necessary data for
`the decryption of the product.
`This method also comprises a detection phase, that is, a
`test phase in order to know which user units have such a
`product. This can be achieved in a centralised way as it is
`directed by the operating center, but
`it can equally be
`established by means of a request to the user units.
`In fact, a unit may be disconnected or may not be capable
`anymore of carrying out
`this transfer. In this case,
`the
`method according to the invention consists in determining
`which are the units that have the desired product and
`ordering the transfer from one unit to another.
`An important aspect of the invention is that
`security into account during these operations.
`Each product is sent in encrypted form. The encryption
`operation is ensured by a transport key CA normally gen-
`erated in a random way. According to an embodiment of the
`invention,
`it is under this form that the operating center
`stores the products.
`When the user Arequests a product X, the key CA, having
`been used to encrypt the product X, is encrypted by a key Ka
`of the user A and is enclosed with the encrypted data of the
`product X.
`When the user unit A is asked to transmit the product X
`to the unit B, only the encrypted product X is transmitted
`onto the bidirectional network. The operating center, know-
`ing the key CA, will encrypt it according to a key Kb of the
`user B and transmits it to him/her. Once the X product
`coming from the A unit and the Kb key arrive at unit B it is
`then possible for the B unit to dispose of product X.
`
`takes
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`3
`The amount of information transmitted from the operating
`center is negligible compared to the transmitted data
`between unit A and unit B.
`
`It is necessary that the link between a group of users is of
`the high speed bidirectional type. On the contrary, it is not
`necessary that the link with the center is of the same type.
`It is also possible that only the link to the users is of the high
`speed type (for example by satellite link), the return path
`being carried out by a classical modem.
`According to an embodiment of implementation of the
`invention,
`the user units are linked to several networks.
`These networks are administered by different operators and
`the method according to the invention allows the use of the
`connection capacities by another operator to carry out the
`transfer.
`
`An example of such a configuration implements a unit
`that comprises a Hertzian receiver (or satellite) and an
`interface with a cable network. According to this example
`the operating center has a one way route to its subscriber
`with the Hertzian route. Nevertheless, the operating center
`has the necessary information for finding the subscriber on
`the cable network of another operator.
`It will then be possible to transfer the requests for prod-
`ucts to the operating center and inversely, the center will be
`able to request the transfer of a product from a subscriber of
`the cable network to another subscriber.
`
`BRIEF DESCRIPTION OF THE DRAWING
`FIGURES
`
`The invention will be better understood with the follow-
`
`ing detailed description that makes reference to the annexed
`figures in which:
`FIG. 1 represents the configuration of the system of the
`invention,
`FIGS. 2 to 4 represent the packages of exchanged data
`between the operating center and the user units.
`FIG. 5 represents a package of exchanged data between
`the operating center and the user units accompanied by a
`header and a transaction registration section.
`FIG. 6 represents a system architecture, according to the
`invention, implementing different operators.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`In FIG. 1 the operating center DS is linked upstream to the
`processing center CCS in charge of administering the
`requests of products to be sent coming from the users. For
`this purpose it has a local storage memory LBD that contains
`the most often requested products. This processing center
`CCS is equally linked to the on-line data base services MS
`which it can solicit at any time. These servers MS are linked
`to the processing center CCS by means of a high speed link.
`The operating center DS is linked by known means to the
`user units MC (cable, fibre optics, Hertzian, ADSL, T1 .
`.
`.
`These units have storage means HD of enough capacity for
`storing at least one product, for example several gigabytes.
`The link between each unit MC and the center can be
`
`either through the same channel in which the data are sent
`to the units or through an alternative channel such as by
`modem, by ADSL connection, or GSM represented by the
`doffed line.
`
`A request is sent by the unit MCa to the operating center
`DS for a product X. The center examines if this product is
`already present in one of the units connected to the same fast
`network NetA, in any of the units MCb, MCc and MCd in
`our example.
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`The concentrator BD in our example does not allow the
`link between the network NetA and NetM. In the inverse
`
`hypothesis, units MCm to MCp would equally be taken into
`account for determining the presence of the product X.
`If the product X is not found in any unit it is sent to the
`unit MCa, encrypted by a transport key CA, this key being
`itself encrypted by a key specific to the unit MCa.
`When the unit MCd requests the same product X to the
`operating center, the center transmits to the unit MCa the
`instruction to transfer the product X encrypted with the key
`CA. In parallel, the operating center sends to the unit MCd
`the transport key CA encrypted by a key specific to the unit
`MCd. The latter is from then on capable of disposing of
`product X.
`FIG. 2 represents a package sent by the operating center
`to a user unit MCa. The product X is encrypted by the key
`CA, itself being encrypted by the key specific to the unit
`MCa, the key Ka.
`The center asks the unit MCa to transfer the product X to
`the unit MCb and it is the package represented in FIG. 3 that
`is sent on the local network.
`
`The operating center sends the key CA, encrypted by the
`key specific to the unit MCb to the latter.
`It is then possible that one user unit contains several
`products in its storage unit. To administer this memory it is
`provided, according to the invention,
`to enclose to each
`product a persistence indicator. In fact, if this product is
`highly specialised, there will be few probabilities that it will
`be requested by another user. In this case, the product will
`be erased from the storage unit after a short period of time.
`Inversely, if this product is a well known novelty, the
`duration of storage will be long in order to satisfy a
`maximum of users.
`
`This persistence indicator can be turned to zero on every
`transfer request or by a command from the operating center.
`This structure allows to administer in an optimal way the
`storage capacities of the user units. In fact, when the product
`X is sent to the unit MCa, it is instantly available on the net.
`In order to anticipate another request from another group the
`MCm unit is requested to store the product X as well. The
`packet of the unit MCa containing the key CA encrypted
`with the key Ka is not stored in the unit MCm.
`The operating center is then ready to face a request from
`a member of the group A(NetA) and of the group M (NetM).
`This practice can be generalised for storing each product
`sent by at least one unit of each group.
`To determine which unit will be chosen, reference can be
`made to the available space in said unit, the preferences of
`the user or of a user group.
`When knowing the profile of the user, it is possible to
`anticipate his/her demand, if the product corresponds to a
`category that is regularly bought by said user. It is equally
`possible to use a unit having a very small use by its user.
`For the administration of a group of users’ profile, it is
`possible to establish the preferences of this group and to
`anticipate their eventual needs. According to the location of
`the considered local network, a group will be more inter-
`ested in sports, and it will be this category of products that
`will have priority of storage in the units of this group.
`One of the problems that
`the operating center may
`encounter in its attempt to transfer from one unit to another,
`is related to the activity of the unit containing the product.
`According to the executions, a unit may not be able to
`send a product on the network and at the same time display
`another product (or the same) for its owner.
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`5
`The center can know to a certain extent the supposed
`activity of each unit but the impulsive buying procedures
`may function without synchronised connection to the oper-
`ating center. The authorisation and the credit is administered
`in the user’s security module.
`This aspect is particularly important when the units have
`no high speed return route to the operating center. In this
`case, it is not desirable to ask each unit its status to know the
`activity on the unit that has the product in its storage means.
`This is why when a unit A requests a given product, said
`unit previously collects the list of products that are stored in
`the units belonging to the same network. This operation is
`very fast and does not penalise the performance of the
`network as the quantity of exchanged data is very small.
`In the data that is sent by the other units to unit A the state
`of each unit is equally included. A unit can then signal that
`it is not available for a download operation.
`Once these data have been collected, unit Asends them to
`the operating center with the request for the desired product.
`The center can verify the state of each unit depending on the
`picture it has in its data base and transmit
`the transfer
`instruction to the unit that is most capable of carrying out the
`transfer without disturbance to its user.
`
`This manner of proceeding allows the operating center to
`regularly dispose of reliable information on the totality of
`user units. It would also be possible to eliminate the picture
`for each unit of the sent products in order to use only the list
`that is received with each request.
`In an embodiment of the invention, unit A sends a request
`specifying the desired product to the local network. The
`other units that have this product make themselves known
`and also signal their availability. According to the chosen
`protocol, unit A immediately requests the transfer of product
`X from the unit that is capable of supplying it. Unit A
`contacts the operating center to inform it of its wish to use
`product X and informs it that this product is already in its
`storage unit. The center has only to transmit the key specific
`to unit A. This can be done through the same channel that is
`used by unit A (for example, by modem) or by the standard
`transmission route (cable, satellite, fibre optics .
`.
`.
`For operational reasons, once the list of stored products in
`their storage unit is transmitted,
`the user units block the
`persistence indicator during the pre-selected time in order to
`avoid that a product is erased during the interval separating
`this inquiry and a possible transfer order.
`When the transfer is carried out, unit A confirms that this
`transfer is successfully finished together with its signature.
`The latter will allow to retrace the use of all
`the sent
`
`products, for example, in order to assess a report to the
`on-line data base service.
`
`When a new film is issued, a previous transmission is
`carried out in order to store this film at least in one unit per
`group. When it is promotionally launched, the demand of the
`users can immediately be satisfied according to the embodi-
`ment.
`
`This method can be generalised in order to use the storage
`capacities of the user units. It is common to connect a great
`number of units to a local network. The use of only a part of
`the storage capacities (for example 50%) of each unit
`represents the possibility of storing a great number of
`products amongst all these units. For a hundred units con-
`nected to a network this means about 500 products imme-
`diately available.
`The preferences of units that have very little activity will
`be selected in order to not penalise the normal use of the
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`unit. It is also possible to store this film in several units per
`group in order to ensure that a distribution can be made at
`all times.
`
`According to an embodiment, different copies of the same
`product are encrypted by a different key CA. When the
`product X is sent to a member of the group NetA, the key
`CA1 is used. It is with a key CA2 that the same product X
`is encrypted and sent to a member of the group NetM. This
`allows to minimise the consequences of a malicious decryp-
`tion of product X. In this case only the members of a same
`group could obtain the key CA1 and dispose of product X
`without compensation.
`The encrypted product is accompanied by a header HD as
`illustrated in FIG. 5. This header is not encrypted so that the
`type of product that is stored in the unit can be recognised.
`It contains the title, the source of the product, the date of
`creation, the duration of validity (or persistence index), a
`signature of the operating center and of the on-line data base
`service with their certifications, and the number of possible
`transfers. This list is not comprehensive and can comprise
`other information.
`
`This block of data is accompanied by a signature in order
`to guarantee that these data are not modified.
`To follow and retrace the different transfers of a product
`from one unit to the other a transaction registration section
`TR is added to said product. This section is divided in to
`modules, each module allowing to retrace one transfer.
`Unit A contains the product X in its storage unit. When a
`transfer to unit B takes place, unit A inscribes its signature
`in the available module with the status “transmitted”. When
`
`the transmission is finished unit B inscribes its signature in
`the same module with the mention “received”.
`
`In this way, with each transfer, the transaction registration
`section is updated with the signature for the units through
`which the file will have passed. Once the maximum number
`of authorised transfers is obtained the transaction registra-
`tion section as well as the header of the product are sent to
`the operating center for their verification. These verifications
`arriving from the user units can be signed by the operating
`center and sent to the on-line data base server MS.
`
`According to an architecture that implements different
`operators such as illustrated in FIG. 6, the on-line data base
`server MS with its data base DB is linked to a processing
`center CCS. In our example, this center is linked to two
`distribution centers DC1 and DC2. The first is linked to user
`
`groups MC by a high speed bidirectional link. Generally a
`user group is linked to a head end BD whose functionality
`can be more or less advanced. The most simple version only
`works as relays between the distribution center and the user
`group below, the most sophisticated varieties allow to make
`transfers between two user groups and have their own
`storage means BDB.
`The user units MC can call the call collection center CC1
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`for the operations of requesting products. According to the
`chosen authorisation modes the distribution center DS1 does
`
`not have the means to authorise the decryption of a product,
`it requests this to the processing center CCS. It is to be noted
`that the distribution center DS1 can propose a service palette
`coming from several sources and is administered by a
`different entity from the one administering the processing
`center. This is the reason why the latter cannot delegate the
`authorisation and demand to receive the requests for prod-
`ucts. This demand can equally be applied to the on-line data
`base service MS. According to an embodiment the product
`X is encrypted by a first key generated by the on-line data
`base service MS and by a second key coming from the
`processing center CCS.
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`7
`According to an embodiment of this configuration several
`processing centers CCS and on-line data base services MS,
`share the supply of these products. The distribution center
`DS receives the requests of the users and relays this demand
`depending on the place where these products are. The
`product header HD includes an indication of the source of
`this product (the on-line data base service) as well as the
`processing center in charge of the latter.
`The distribution center DS2 is connected to the users by
`a satellite link. This link arrives at a local server HE that
`
`regroups several services. This server then distributes these
`services for example by means of a cable network.
`For the return route to the processing center this server is
`connected to a call concentrator CC2.
`I claim:
`
`1. Asystem comprising at least one operating centre that
`has a great number of products and a plurality of user units
`including security and storage means, wherein all or a part
`of the user units are connected to at least one local network,
`the link between a first user unit and a second user unit is of
`
`the bi-directional type said user units comprise means for
`transferring a product encrypted with a transport key and
`stored in the storage means of the first user unit for sending
`to the second user unit,
`the operating centre comprises
`means for transmitting the authorization to the second unit
`to decrypt the product.
`2. A system according to claim 1, wherein the first user
`unit comprises means for transmitting the encrypted product
`to the second user unit, said unit comprising decryption
`means, in its security means, of the transport key sent by the
`operating centre and encrypted with a key specific to the
`second user unit.
`
`3. Asystem according to claim 1 or 2, wherein at least said
`second user unit comprises means for requiring and reading
`the list of products that are stored in the storage units of the
`other user units connected to the same local network and for
`
`sending this list to the operating centre.
`4. A method for optimizing the transmission upon request
`of products between an operating and distribution centre and
`a plurality of user units comprising the following steps:
`sending a request for transmission of a product to the
`operating centre from second user unit connected to a
`local bi-directional network,
`determining if the requested product is already in any first
`user unit connected to the same local network,
`in the negative event,
`transmitting from the operating
`centre to the second user unit and storing the product in
`encrypted form in said second user unit,
`
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`in the positive event, ordering the transfer of the product
`from the first unit to the user unit,
`
`transmitting by the operating centre the necessary data for
`the decryption of the product.
`5. Amethod according to claim 4, the product is encrypted
`by a transport key, which key being encrypted with a key
`specific to the second user unit and sent to the latter by the
`operating centre.
`6. A method according to claim 4, consisting in ordering
`the storage of the product one user unit among the user units
`connected to the same local network.
`
`7. Amethod according to claim 4 wherein the selection of
`the user unit, chosen among the user units connected to the
`same local network for receiving the product and not having
`requested the product, is carried out according to a con-
`sumption profile of said unit.
`8. A method according to claim 7, wherein the consump-
`tion profile is established according to the type of product
`normally consumed.
`9. A method according to claim 7, wherein the consump-
`tion profile is established according to the activity ratio of
`said user unit.
`
`10. A method according to claim 4 consisting in, prior
`sending a request to the operating centre, determining the
`products that are stored in the units connected to the same
`network and transmitting these data to the operating centre.
`11. A method according to claim 4 consisting in sending
`a product, prior to a user request, to at least one user unit
`among the user units connected to the same local network.
`12. A method according to claim 4, consisting in:
`encrypting the product with a second key by a data server
`connected to the operating center or processing center,
`transmitting the request for the product to the data server,
`which after verification,
`returns the second key
`encrypted with a transport key defined by the operating
`or processing centre.
`13. A method according to claim 12, wherein the product
`comprises a header and a transaction registration zone, and
`consisting in marking this zone with the signature of the
`emitting unit and with the signature of the receiving unit.
`14. A method according to claim 13, wherein the operat-
`ing centre can at any tune request the re-emission of the
`transaction zone accompanied by the product header to a
`user unit for verification.
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