METHOD FOR AUTHORISING
FIELD OF INVENTION
[0001] This invention refers in general to the transmission of encoded multimedia
digital content to customer devices from subscribers to a service provider.
BACKGROUND
[0002] Figure 1 illustrates a pay-TV system and in a general manner, a subscriber
selects an event or programme for desired viewing and pays to receive the selected
programme.
[0003] The selected programme is transmitted in code in order to ensure that
unauthorised customers cannot decode and descramble a payable event.
[0004] Encoded and scrambled multimedia digital programmes are disseminated by a
broadcast server through a diffusion communications network to a group of subscribers.
[0005] Pay-TV systems include pay per view services for purchasing events of the
sporting fixture type such as a football match, or a film etc thus enabling subscribers to
purchase a specific event prior to its broadcast and also during transmission of the actual
event.
[0006] A subscriber may purchase a specific event by making a telephone call to a
subscriber management centre in order to purchase a selected event.
[0007] In addition, the subscriber may also purchase the event through a customer
television descrambling device or set-top-box STB to the subscriber's audiovisual screen.
Through interaction with the purchase menu, the subscriber selects a desired event and
through a return channel, the STB descrambler transmits a purchase message in the form
of data stream which includes unique identification data of both the subscriber wishing to
purchase the event and a subscriber application server.
[0008] One disadvantage of this system for purchasing an encoded scrambled
multimedia digital event is the total time required to confirm and emit a purchase
confirmation message to the subscriber when a large number of purchasing requests are
received in a subscriber management centre, over a short period of time, with impulsive
purchasing due to popular sporting events such as the final of a tennis tournament, or the
final of the football World Cup for example.
[0009] The time required is based on the number of applications received, that is, the
volume of data stream traffic and the number of subscribers making a request. Therefore,
there may be a period of time passing, which may seem very long to the subscriber before
the purchase can be validated by the management centre and the event may have actually
begun, that is, the subscriber is only able to view part of the event having paid to view the
whole fixture.
[001 0] Furthermore, the management centre cannot validate the request to purchase a
digital programme received from the subscriber and/or the management centre may not
receive the purchase request itself due to the fact that it has received an avalanche of
purchase requests resulting in a bottleneck at the management centre.
SUMMARY
[001 1] This invention seeks to resolve or reduce one or more of the disadvantages
mentioned above by means of an authorisation method for accessing an encoded
scrambled digital multimedia event through a broadcast communications network as
defined in the claims.
[0012] In an embodiment of the authorisation method for accessing scrambled
multimedia digital programmes with access control and broadcast in a one-way direction
by a broadcast server to a set of customer descrambling devices through a
communications network, it comprises the stages of transmission of a message requesting
access to a broadcast scrambled multimedia digital programme, including a descrambling
device identifier and an identifier of a specific multimedia digital programme, from the
decoder to the access licence server; comparison in the licence server of the decoder
identifier and the identifier of a specific multimedia digital programme broadcast with a
specific level of credit stored in the licence server, if the comparison is positive,
reduction of the value of the credit level stored by an amount depending on the type of
digital multimedia programme; transmission of access authorisation and descrambling
key from the licence server to the descrambler; retransmission of the authorised request
message received to the broadcast server, once the multimedia digital programme is
being broadcast or has finished in order to charge the subscriber and transmission from
the broadcast server of a payment message in order to restore the credit level stored in the
licence server.
[001 3] One purpose of the access authorisation method is to avoid bottlenecks in a
subscriber application server when the subscribers issue access authorisation requests to a
predetermined encoded and scrambled multimedia digital programme with access control
considered as massive, as access has been requested by a considerable number of
subscribers in a short period of time before and/or during the broadcast of the scrambled
programme.
[0014] Another purpose of the invention is to simplify the billing procedure for
broadcasted scrambled programmes and to increase the security of the invoicing method
thus preventing fraudulent intervention when charging the subscriber's account on the
side of the network and not on the customer's side.
[001 5] A further purpose is to provide a method for invoicing video and audio
programmes broadcast with massive demand with simple scalability.
BRIEF DESCRIPTION OF THE FIGURES
[001 6] A more detailed explanation of devices and/or methods in accordance with
embodiments of the invention are provided in the following description based on the
attached figures in which:
[001 7] Figure 1 shows a block diagram of an invoicing system for scrambled video
and audio programmes with controlled access broadcast from a broadcast server thought
a broadcast network to a group of subscribers and
[001 8] Figure 2 shows a block diagram of an authorisation system for access to a
scrambled video and audio programme with access control broadcast from a broadcast
server through a broadcast network to a group of subscribers.
DESCRIPTION OF EMBODIMENTS
[0019] With reference to figure 2, which shows a block diagram of a broadcast system
of encoded and scrambled multimedia digital content in which a broadcast server is
connected to an access licence server and a set of STB customer descrambling devices
through a broadcast network.
[0020] A licence server is in turn, connectable to a specific number of customer STB
descramblers via the same communications network of the internet IP type for example.
[0021] The broadcast server transmits to the group of subscribers a one way encoded
and scrambled multimedia digital data stream. Different service providers transmit digital
video and audio programmes to the broadcast server so that it will broadcast the data
stream which includes the encoded and scrambled multimedia digital programmes.
[0022] A predetermined programme selected by a subscriber is shown on an audiovisual
screen if the subscriber receives a positive access control signal from the access licence
server, that is, the subscriber who has made an access request to a predetermined
multimedia digital programme is a reliable subscriber due to the fact that the licence
server has stored a predetermined value corresponding to a credit registration in a storage
unit or data base of a CAS access control system.
[0023] The credit registration corresponds to a credit value associated with a credit
signal transmitted from the broadcast server through the broadcast network.
[0024] The CAS access control is authorised to generate access authorisations to
descrambling keys for scrambled digital programmes. The licence server transmits
authorisations and keys to the subscribers making access requests for an encoded and
scrambled programme.
[0025] When a subscriber subscribes to a predetermined service provider, the provider
generates a trust level value for the subscriber. The trust level is associated with a
predetermined credit value. The CAS access control database stores the value of the
credit amount associated with the trust level of each subscriber.
[0026] The trust level and therefore, the value of the credit amount that the operator
assigns to a subscriber may be changed over time by the supplier.
[0027] In the event that a supplier forecasts that a particular event associated with a
multimedia digital programme may be requested on a massive scale by subscribers, the
supplier transmits in advance information data which includes a unique identifier
associated with the predetermined multimedia digital programme, in the form of
metadata, to the set of licence servers and to the subscribers' STB descramblers by means
of the broadcast server and the broadcast network.
[0028] In addition, the supplier disseminates advice messages associated with the event
which is about to be broadcast, for example through the emission of advertisements in
various formats, electronic programme guide, EPG etc.
[0029] Therefore, each subscriber wishing to acquire or purchase a massive digital
programme knows the unique identifier corresponding to the programme he wishes to
view.
[0030] In order to avoid overloading a subscriber application server connected to a
broadcast server with access authorisation request messages which include the massive
multimedia digital programme identifier, each request message is transmitted or
retransmitted to the licence server, in such a way that the number of messages that the
licence server should manage is restricted. It should be noted that each licence server is
connectable to a limited number of customer STB devices.
[0031] The access request message is generated by an application for selecting a
multimedia digital programme executed by the subscriber's STB descrambler.
[0032] The request message which includes the unique identifier of a programme
associated with an event considered as massive and a similarly unique identifier of a
subscriber STB descrambler, is transmitted from an STB descrambler to a CAS control
access module of the licence server in order to obtain an authorisation or authorisation
data and the key for descrambling the CS control word.
[0033] The control word thus descrambles the data corresponding to the scrambled
multimedia digital programme with access control distributed from the broadcast server.
[0034] The unique identifier included in the request message received in the CAS
access control module is identified by said module as being associated with a massive
programme and, instead of forwarding the request message to the subscriber application
server, the CAS control module compares that trust level associated with the unique
identifier of the STB decoder received and its associated credit threshold; if the
comparison is positive, the CAS control module generates the corresponding access
authorisation and the descrambler key so that it will be transmitted by licence server to
the subscriber's STB descrambler. The multimedia descrambled programme data
decoded by the STB descrambler may be played immediately on the audiovisual viewing
screen.
[0035] When the CAS control module makes a positive comparison, that is,
corresponding to a predetermined trust level value and to a predetermined credit
threshold, the trust level is maintained and the value of the stored credit amount
associated with said level of trust, is reduced or charged at an amount assigned by the
supplier to the scrambled multimedia digital programme selected or purchased by the
subscriber.
[0036] In the event of a negative comparison, that is, the trust level assigned to the
customer and/or the credit is negative, that is, the trust level assigned to the customer
and/or the credit is inadequate, the licence server is not permitted to transmit an access
authorisation and the corresponding descrambling key to enable the subscriber's STB
decoder to descramble the control word received in the ECM (entitlement control
message), for example, and in this way massive multimedia digital scrambling cannot be
decoded with access control by the requesting subscriber's STB decoder.
[0037] The access control module may make several comparisons simultaneously for
request messages which include the same unique massive programme identifier.
[0038] When the access control module stops receiving access request messages which
include the same massive programme unique identifier, that is, when the massive event
has begun and/or finished, the broadcast server, prompted by the access control module,
retransmits to the subscriber licence server the set of access request messages authorised
by the access module based on the stored credit data.
[0039] The broadcast server makes the transmission in a distributed manner in order to
avoid, in turn, overloading the management system.
[0040] It is the application server which actually carries out the billing of the
multimedia digital programme, associated with an event considered to be massive, for
each requesting subscriber in a manner which is known in the state of the art.
[0041] Furthermore, the application server generates and transmits reloading messages
for restoring, increasing or reducing the amount of credit stored by the access control
module and/or modification messages for maintaining or changing the trust level
associated with each requesting subscriber, based on the degree of satisfaction of the
sums recharged and owed to account or billed to a subscriber.
[0042] It should be noted that the access authorisation method for an event considered
to be massive is adapted to the pre-pay type billing system, payment subsequent to billing
of the scrambled multimedia digital programme with access control broadcast by a
broadcast server through a broadcast network.
[0043] However, the application server avoids receiving all the request messages
relating to a programme which is considered to be massive prior to and during the
broadcast of said massive programme.
CLAIMS
1. A method for authorising for access to scrambled multimedia digital
programmes with access control and broadcast one way by a broadcast server ( 11) to a
set of customer descrambling devices (13) through a communications network;
characterised in that the method comprises the stages of:
> Transmission of an access request message to a broadcast scrambled
multimedia digital programme, including a descrambling device identifier (13)
and an identifier of a specific multimedia digital programme from the
descrambler (13) to an access licence server (12).
Comparison in the licence server (12) of the descrambler identifier (13)
and of the identifier of a specific multimedia digital programme with a specific
trust level associated with a predetermined credit level stored in the licence
server (12), if the comparison is positive,
Reduction in the value of the credit level stored of an amount depending on
the type of multimedia digital programme,
> Transmission of an access authorisation and descrambling key from the
licence server (12) to the descrambler (13),
> Retransmission of the authorised request message received to the broadcast
server ( 11), when the multimedia digital programme is being broadcast or has
finished, in order to charge the subscriber and
> Transmission from the broadcast server ( 11) of a recharging message in
order to re-establish the credit level stored in the licence server (12).
2. A broadcast server connectable to a set of customer descrambling devices (13)
through a communications network in order to broadcast scrambled multimedia digital
programmes with access control; in which the broadcast server ( 11) is adapted to receive
an access request for a broadcast scrambled multimedia digital programme, including a
descrambling identification device (13) and an identifier of a specific multimedia digital
programme, from an access licence server (12), once the multimedia digital programme
is being played or has finished.
3. Server in accordance with claim 2; where the broadcast server is adapted to
transmit a recharging message in order to re-establish a credit level stored in the licence
server (12).
4. Server in accordance with claim 2; where the broadcast server is adapted to
make the billing charge in a customer account associated with the requesting customer.
5. A licence server for access to scrambled multimedia digital programmes
broadcast one-way by a broadcast server ( 11) to a set of customer descrambling devices
(13) through a communications network; the licence server (12) is adapted to receive an
access request message to a scrambled broadcast multimedia digital programme,
including a descrambling device identifier (13) and an identifier for a specific multimedia
digital programme from the customer's descrambler (13).
6. Server in accordance with claim 5; in which the licence server (12) is adapted
for comparing the descrambling identifier (13) and the identifier of the specific
multimedia digital programme broadcast with a specific trust level associated with a
predetermined stored credit level; if the comparison is positive it reduces the stored credit
level by an amount depending on the type of multimedia digital programme and transmits
an access authorisation and descrambling key to the decoder (13).
7. Server in accordance with claim 6; in which the licence server (12) is adapted to
retransmit the authorised request message received to the broadcast server ( 11), when the
multimedia digital programme is being played or has finished.
8. Server in accordance with claim 6; in which the licence server (12) is adapted to
receive from the broadcast server ( 11) a recharging message in order to re-establish the
stored credit level.
9. A computer programme can be loaded in an internal buffer of a computer with
input and output units and a processing unit, where the computer programme comprises
codes which, when executed by the computer, cause the computer to perform the steps of
claim 1.