U.S. patent application number 14/365761 was filed with the patent office on 2014-12-04 for network terminal validation.
The applicant listed for this patent is BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY. Invention is credited to Michael Rizzo, Paul Martin Skirrow.
Application Number | 20140359748 14/365761 |
Document ID | / |
Family ID | 47291170 |
Filed Date | 2014-12-04 |
United States Patent
Application |
20140359748 |
Kind Code |
A1 |
Rizzo; Michael ; et
al. |
December 4, 2014 |
NETWORK TERMINAL VALIDATION
Abstract
A media asset location request redirection system causes a user
terminal (11) to redirect first media asset location data (22)
relating to a first content delivery network (16) such that the
media asset location request is directed to a second content
delivery platform (17), by means of a proxy redirection server (18)
which translates the first media asset location data (21, 251) into
second media asset location data (26) relating to the second
content delivery network. Use of the proxy redirection server (18)
is controlled by an authentication process, in which the user
terminal (11) and proxy redirection server (18) perform a mutual
authentication process to determine whether the redirection server
(18) should accept the request for a media asset location.
Inventors: |
Rizzo; Michael; (London,
GB) ; Skirrow; Paul Martin; (London, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY |
London |
|
GB |
|
|
Family ID: |
47291170 |
Appl. No.: |
14/365761 |
Filed: |
November 29, 2012 |
PCT Filed: |
November 29, 2012 |
PCT NO: |
PCT/GB2012/000875 |
371 Date: |
June 16, 2014 |
Current U.S.
Class: |
726/10 |
Current CPC
Class: |
H04L 63/126 20130101;
H04L 45/74 20130101; G06F 21/10 20130101; H04L 63/0823 20130101;
H04L 63/08 20130101; H04L 63/168 20130101; H04L 65/40 20130101;
H04L 69/22 20130101; H04L 63/0281 20130101; H04L 67/2814 20130101;
H04L 63/0272 20130101; H04L 63/0869 20130101 |
Class at
Publication: |
726/10 |
International
Class: |
H04L 29/08 20060101
H04L029/08; H04L 29/06 20060101 H04L029/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 2011 |
EP |
11250928.6 |
Dec 16, 2011 |
EP |
11250929.4 |
Dec 16, 2011 |
EP |
11250930.2 |
Claims
1. A proxy redirection server for converting a first media asset
location in a data request to a second media asset location
according to a concordance, the redirection server being arranged
to receive an authentication certificate enabling the setup of a
secure communications channel over which a data request is to be
transmitted, and comprising an authentication processor for
checking the authentication certificate for its validity, and a
response generator controlled by the authentication processor, for
generating a response to the data request, including the second
media asset location, if the validity check is successful.
2. A proxy redirection server according to claim 1, wherein the
response generator has means to generate a time/ stamp and expiry
time as part of the response, indicative of the time for which the
media asset locator contained in the response is valid.
3. A proxy redirection server according to claim 1, wherein the
response generator has means to generate an address restriction
specifying a network address from which the asset may be
accessed
4. A proxy redirection server according to claim 1, wherein the
response generator is responsive to device-specific data received
in the data request to retrieve a media asset location selected
according to the device-specific data.
5. A user terminal configured to cause a first media asset location
associated with a first content delivery network to be converted to
a second media asset location associated with a second content
delivery network, under the control of a proxy redirection server,
the user terminal being configured such that a request identifying
a first media asset location is redirected to the proxy redirection
server, and to receive an instruction to generate a request
identifying a second media asset location in the second content
delivery network, the device being arranged to transmit an
authentication certificate to the proxy redirection server for
validation prior to sending the request.
6. A user terminal according to claim 5, wherein the user-terminal
is arranged to generate device-specific data with the generated
request.
7. A user terminal according to claim 5, wherein the authentication
certificate is embodied in a downloadable data file installed on
the device.
8. A user terminal having control data for causing a processor to
be configured to operate according to claim 5 embodied in a
downloadable data file installed on the device.
9. A method of configuring a user terminal by transmitting a
downloadable data file to the device for installation on the
device, the downloadable data file including an authentication
certificate file, and operating instructions to configure the
device to operate according to claim 5.
10. A method of operating a media asset location request
redirection system to cause a user terminal to redirect first media
asset location data relating to a first content delivery network
such that the media asset location request is directed to a second
content delivery platform, in which the request is directed to a
proxy redirection server which translates the first media asset
location data into second media asset location data relating to the
second content delivery network, and use of the proxy redirection
server is controlled by an authentication process, in which the
user terminal transmits a certificate to the proxy redirection
server and the proxy performs an authentication process to
determine whether to accept the request for a media asset
location.
11. A method according to claim 10 wherein the proxy redirection
transmits a timestamp indicative of the time for which the media
asset locator contained in the response is valid with the second
media asset location, and the second content delivery network uses
the time stamp to determine whether a media asset location request
received from a user terminal is to be met.
12. A method according to claim 10, wherein the response generator
generates an address restriction specifying a network address from
which the asset may be accessed, and the second content delivery
network uses the address restriction to determine whether a media
asset location request received from a user terminal is to be
met
13. A method according to claim 10, wherein the user terminal is
configured to redirect media asset data requests to the proxy
redirection server, and to generate the signature, in accordance
with operating instructions downloaded from a service platform
associated with the second content delivery platform.
14. A method according to claim 10, wherein the media asset
location data generated by the proxy redirection server includes
device-specific data configured according to the user terminal from
which the request for data is received.
Description
[0001] This invention relates to data retrieval processes, and in
particular a process for retrieving data files from a content
delivery database and delivering them to end users over a data
network such as the "internet". Such data files carry various forms
of content, such as video or sound files, software upgrades,
etc.
[0002] The present invention involves the selection and use of a
content delivery network other than a default network selected by a
content service provider, without modification to the content
service provider's own service platform.
[0003] This application is one of three filed contemporaneously,
each relating to an invention which facilitates the operation of
such services. The other two applications, filed on the same date
as the present application and claiming priority from the same
three applications, are entitled "Data Retrieval Redirection" and
"Proxy Server Operation". These three inventions may be used
individually, or together as will be described in the
specification.
[0004] The following terms are used in the specification with the
meanings given here. Reference is made, for illustrative purposes,
to the conventional system depicted in FIG. 1.
[0005] Access Service network (12, FIG. 1)--a data communications
network, through which a user terminal may be connected to other
network nodes to retrieve data files
[0006] Authenticated Channel--a secure channel arranged to transfer
data from a server to a client if and only if the server has been
authenticated by the client e.g. one-way https. A Mutually
Authenticated Channel is an Authenticated Channel where data can
only be transferred if the Client and the Server have both
authenticated each other, typically using X.509 certificates (e.g.
https mutual).
[0007] Browser (13, FIG. 1)
[0008] An application operating on a user terminal which allows a
user to select and access server applications at a remote
source
[0009] Client Player (14, FIG. 1)
[0010] An application, typically on a user terminal, for processing
media files received from a data source and processing them for
delivery to a user interface
[0011] Client Proxy Configuration--a configuration in the User
terminal to force it to send requests using specific Asset Locators
via a Proxy Server such as a Redirection Server.
[0012] Content Delivery Network (CDN: 160, FIG. 1).
[0013] a distribution system able to deliver data files to user
terminals on demand. (160, FIG. 1).
[0014] Content Distribution Provider--provider of a Content
Delivery Network. Not necessarily associated with, or controlled by
the Network Service Provider or Content Service Provider.
[0015] Content Service Provider--a provider of data for an original
content server,
[0016] Device Identity--a Unique device identifier, often taking
the form of a certificate (and associated private key) that can be
used by a server to authenticate the device. This may be burned
into the device as part of the manufacturing process.
[0017] (Digital) signature--a mathematical scheme for demonstrating
the authenticity of a digital message or document. A valid digital
signature gives a recipient reason to believe that the message was
created by a known sender, and that it was not altered in transit.
Digital signatures are commonly used for software distribution,
financial transactions, and in other cases where it is important to
detect forgery or tampering.
[0018] Media Asset (280, FIG. 1)
[0019] a data file such as audio, video, html, for processing by a
Player
[0020] (Media) Asset Locator (22, 250 FIG. 1)
[0021] a data item comprising a unique identifier for a (media)
asset, for example a URL or URI, (Universal Resource
Locator/Identifier) typically comprising: a scheme (identifying a
protocol such as http), a server location (such as an Internet
domain) and an asset location on the server (such as a directory
path and filename). The scheme may specify use of a secure
connection e.g. https.
[0022] Media selector
[0023] a system operated by a Content Service Provider that is used
to determine an appropriate content delivery network and media
asset locator for the purpose of delivering of a media asset to a
specific user terminal.
[0024] Network Location--an identification or address of the device
on a network, such as an IP address or hostname.
[0025] Network Service Provider--the provider or operator of an
access service network
[0026] Original Content Server (16, FIG. 1)
[0027] server provided by the Content Service Provider, from which
data files are distributed either directly to users, or through a
Content Delivery Network.
[0028] Proxy Server--a server that acts as an intermediary for
requests from clients seeking resources from other servers.
Examples include caching servers, load balancers, and redirection
servers:
[0029] Public Key, private key--two complementary encryption keys
(with associated algorithms) that allow the origin or destination
of data to be confirmed. Data encrypted with one key can be
decrypted with the other. The private key is only available to the
user whose identity is to be confirmed, but the public key is made
available to all users. This allows any users with the public key
to confirm the origin of data encoded using the private key, and/or
to ensure that data encoded using the public key can only be read
by the holder of the private key.
[0030] Public key certificate (also known as a digital certificate
or identity certificate)--an electronic document which uses a
digital signature to bind a public key with information that
identifies a person or an organization. The certificate can be.
used to verify that a public key belongs to an individual. The
public key can be proved by a "challenge"--the challenger transmits
a data message, encrypted using the public key, to the originator.
This can only be decoded if the originator has the private key
matching the public key. The originator then returns the decoded
message to the challenger, which checks the decoded message it
receives against the original message. The digital signature
originates from a trusted 3.sup.rd party certification authority
which can vouch for the authenticity of the certificate.
[0031] Redirection Server (18, FIG. 2)--a server that accepts
requests including Asset Locators from a Client and responds with a
redirection message containing a different Asset Locator to that
originally requested. The Redirection Server uses a look-up table
or specific rules to generate a new Asset Locator for each Asset
Locator provided by the Client. A "Secure Redirection Server" is a
Redirection Server which will only receive requests via an
Authenticated Channel
[0032] Signed Asset Locator--an asset locator that is securely
restricted to consumption by a device with a known identity or
network location and/or within an allowed time frame. The locator
includes a constraint which is typically derived from data items
such as: device identity, time, expiry time or time range, Asset
Time Stamp, Asset Locator (e.g. uri), or source Network Location,
and protected using a hash or encryption algorithm using a secret
key to ensure it cannot be forged.
[0033] Time Stamp--an item of data indicating the time an asset was
last created or modified, for example a time stamp is typically
provided for each file managed by an Operating System or Filing
System. In the present specification the time stamp is used to
identify the period of validity of the asset, to prevent its use
after that period has expired.
[0034] User terminal (1.1, FIG. 1)
[0035] a device, such as a computer, handheld device or Set Top
Box, typically in a customer's home, and used by the customer to
retrieve data files from a remote source
[0036] Media assets are available from a wide range of different
data hosts, and can be routed over various access, service
networks, under the control of different service providers, to a
range of user terminals. In a typical arrangement, content is
identified by an Internet address (Universal Resource
Identifier--"URI"). The format of the URI does not necessarily
indicate the nature of the content, and so there is no reliable way
for the network, or the user terminal, to identify the type of
content from the URI alone.
[0037] The URI may be accompanied by a digital signature in order
to confirm that the client making the request is authorised to
access the content delivery network. Examples are described in
United States Patent Application US2009/031368 and European Patent
Application EP1278112.
[0038] A Content Service Provider often has relationships with one
or more Content delivery networks, and uses a media selector to
identify the best CDN and associated Media Asset Locator to `serve
a given user terminal. The use of a media selector enables a
Content Service Provider to use a CDN without losing sight of the
requests for its content, and to enforce timing constraints without
having to rely on precise synchronisation with the CDN. In
particular, television "catch-up" content is often made available
for a limited period only, but this limitation is difficult to
police if the content is also duplicated in caches operated by
CDNs. Content may also need to be withdrawn at short notice, for
example if the information in the content becomes out of date, or
subject to a legal injunction. The original content provider can
replace the content with some other` response, but the CDN might
continue to make available its cached copies.
[0039] A Network Service Provider may have a preferred Content
delivery network which can be used to deliver a range of benefits
including: lower network cost, use of prioritised delivery over the
network, exemption from any broadband usage limits, and transcoding
of assets for delivery to different user terminal types.
[0040] It may be cheaper for a Network Service Provider to use
their preferred CDN in place of the Content Service provider's
default CDN. For example the CDN may locate streaming servers close
to the edge of the network, so as to minimise the distance over
which media needs to travel in order to reach the user
terminal.
[0041] The Network Service Provider CDN may also enable video
content to be identifiable so that it can be prioritised over other
data in order to avoid, or minimise the possibility of, exhaustion
of buffered content at the user end, resulting in interruption of
the content being viewed.
[0042] Some media assets, particularly video streams, can require a
relatively high bit rate over a relatively long period, and so can
make up a significant proportion of any usage limit applicable to
an Internet users account. Some service providers allow content
from an authorised source, such as the website of a television
broadcaster, to be exempt from such usage limits, for example
because such content is paid for in some other way, such, as a
subscription or advertising revenue. It is therefore desirable that
such content be identifiable, and this can be facilitated though
use of the Network Service provider's choice of CDN.
[0043] Although the same URI (Universal Resource Indicator) might
be provided by a media selector to all user terminals requesting
content, it is often desirable to deliver content that has been
configured to be appropriate for the type of user terminal
requesting the content, for example the appropriate video format,
bit-rate, meta-data etc. In particular, where a content service
provider does not provide explicit support for specific user
terminal types, the service provider may wish to transcode media
assets into appropriate formats before delivering them-to the user
terminal. This might be achievable via use of an appropriate CDN
with transcoding capability.
[0044] The Network Service Provider may also wish to monitor and
control access, so that it can provide services tailored to its own
customers. For example it may charge for certain material, or
restrict access, for example to prevent content unsuitable for
children from being downloaded during times when they are likely to
be using the service. It may also substitute some content, for
example to provide advertising or news more relevant to the user's
location than that provided in the original content. These
capabilities can all be facilitated through use of the Network
Service Provider's choice of CDN.
[0045] There are therefore many reasons why a Network Service
provider may require its customers to use a CDN other than the
default CDN nominated by the Content Service Provider.
[0046] One way to achieve this would be for providers of such
content to respond to data requests from subscribers of an approved
network service provider by routing the requested data through a
dedicated service platform (170, FIG. 1) hosted by the network
service provider, instead of the content distribution provider's
own network 160 to which the user would otherwise be directed by
the media selector 15. However, this requires modification to the
content provider's media selector platform 15 to identify and
authenticate users permitted to access the dedicated platform 170.
This can be difficult to achieve, especially if more than one
network service provider and/or more than one content provider are
involved,.
[0047] This raises the question as to how a Network Service
Provider might itself redirect requests that are targeted at the
Content Service Provider's choice of CDN to its own choice of
CDN.
[0048] Techniques for re-direction of requests via a proxy
redirection server are known in the industry. However these can
give rise to a number of security related challenges in the
specific context under discussion. Specifically: [0049] (i) the
Network Service Provider may wish to strengthen the security used
in relation to signed media asset locators, so that customers do
not gain illegitimate access to benefits (such as network
prioritisation or usage volume exemption) for other data assets.
Where a network service provider uses Carrier Grade NAT (network
address translation), the network service provider may require a
solution for signing media asset locators using the user terminal
network address where the user terminal's public address seen by
the content service provider is not the same as the private address
seen by the network service provider's CDN. [0050] (ii) the content
service provider would not want its own signed media asset locators
to be compromised by a rogue user terminal using the proxy
redirection server, [0051] (iii) if the content service provider
specifies https for media delivery, then this requires special
treatment to enable use of a redirection proxy
[0052] Failure to address security concerns related to such
re-direction could allow rogue users and or devices to make use of
network prioritisation facilities in the broadband access network
to which they are not entitled, or to gain exemption from broadband
usage policies to which they are not entitled, or to gain access to
content to which they are not entitled.
[0053] Furthermore, standard re-direction techniques cannot be used
where a content service provider media selector has responded with
a media asset locator that is based on a secure scheme such as
https. In such a situation, the proxy redirection would not
normally be able to see the contents of the request, and to return
an appropriate redirection response.
[0054] Some network providers have accommodated the current
shortage of IPv4 addresses by consolidating several user addresses
under the same public network address, allocating separate private
addresses to the individual users known as Carrier Grade Network
Address Translation (CG-NAT). It is thus not always possible for a
content delivery provider external to the network to distinguish
and authenticate requests from individual users, as they may share
the same public address. The external content delivery service can
only determine whether it should deliver data to the public
address, and cannot distinguish between users sharing that address.
This makes it impossible for the content service provider's CDN to
employ signed media asset locators based on network addresses, and
means that URI's could be passed on to enable access by users not
entitled to such access.
[0055] The present invention provides features of an alternative
system which overcomes some of these difficulties whilst requiring
no modification to the content provider's operating system. The
inventions of the applicant's co-pending applications, entitled
"Data Retrieval Redirection" and "Proxy Server Operation" filed
contemporaneously with the present application, provide further
features which may also be used in co-operation with the present
invention.
[0056] It is known to use a "proxy" configuration in which data
messages, for example, content requests, addressed to one internet
address are sent to a proxy server. This allows the existence or
characteristics of an origin server to be hidden, and can be useful
for load balancing, termination on secure networks (behind a
firewall), mobility, server-based decryption (SSL termination) etc.
The proxy can be used, for example, to allow authentication of a
user; in order to grant permission to access certain data,
effectively acting as a trusted intermediary. A conventional proxy
appears to a user terminal to stand in the place of the requested
data source. Conversely, a "reverse proxy" appears to the data
source to stand in the place of the actual requesting user
terminal.
[0057] In particular it is also known to use a "redirection proxy"
configuration in which content requests, addressed to a content
delivery network are re-directed to another content delivery
network by a proxy redirection server. Such a system is known from
"Building Robust Network Services Through Efficient Resource
Management" (Limin Wang, PhD dissertation, Princeton University,
November 2003) However, the system proposed therein would allow
unlimited access to the second content delivery network. In
particular, the proxy could be used by a rogue client to turn a URI
with an expired/faked signature into a new URI with a valid
signature. The URI could also be forwarded by one user to another,
for whose use it was not intended, thus allowing multiple
accessions of the second content delivery network by users not
authorised to use it, and without the primary data supplier being
aware of such accessions.
[0058] According to the invention, there is provided a method of
operating a media asset location request redirection system to
cause a user terminal to redirection first media asset location
data relating to a first content delivery network such that the
media asset location request is directed to a second content
delivery platform, in which the request is directed to a proxy
redirection server which translates the first media asset location
data into second media asset location data relating to the second
content delivery network, and use of the proxy redirection server
is controlled by an authentication process, in which the user
terminal transmits a certificate to the proxy redirection and the
proxy performs an authentication process to determine whether to
accept the request for a media asset location.
[0059] A further aspect of the invention provides a proxy
redirection server for converting a first media asset location in a
data request to a second media asset location according to a
concordance, the redirection server being arranged to receive an
authentication certificate enabling the setup of a secure
communications channel over which a data request is to be
transmitted, and comprising an authentication processor for
checking the authentication certificate for its validity, and a
response generator controlled by the authentication processor, for
generating a response to the data request, including the second
media asset location, if the validity check is successful. In a
preferred arrangement, the response generator has means to generate
a time stamp and expiry time as part of the response, indicative of
the time the response to the data request is generated. Preferably,
the response generator is responsive to device-specific data
received in the data request to retrieve a media asset location
selected according to the device-specific data. The response
generator may also generate an address restriction specifying a
network address from which the asset may be, accessed, the second
content delivery network using the address restriction to determine
whether a media asset location request received from a user
terminal is to be met
[0060] In a complementary aspect, the invention provides a user
terminal configured to cause a first media asset location
associated with a first content delivery network to be converted to
a second media asset location associated with a second content
delivery network, under the control of a proxy redirection server,
the user terminal being configured such that a request identifying
a first media asset location is redirected to the proxy redirection
server, and to receive an instruction to generate a request
identifying a second media asset location in the second content
delivery network, the device being arranged to transmit an
authentication certificate to the proxy redirection server for
validation prior to sending the request.
[0061] This arrangement allows the service provider to maintain
control of the provision of the redirection service to authorised
user terminals. This invention therefore protects against use of
the proxy redirection server as a way of bypassing validation of
signatures provided e.g using the processes described in U.S. Pat.
No. 5,805,803 and EP1278112. By use of a mutually authenticated SSL
(secure sockets layer) or TLS (transport layer security) connection
between the user terminal and the redirection server, it can be
ensured that the redirection server only accepts requests from
genuine user terminals that are known to be trusted.
[0062] Preferably, the user terminal may have the necessary
certificate, and/or the control data for causing the processor to
be configured according to the invention to operate this way
installed on initial manufacture. Alternatively it may be installed
subsequent to manufacture by providing a downloadable data file on
a medium such as a computer disc, or secure download from another
computer or over the data communications network itself.
[0063] The user terminal is configured so that only URI's delivered
from the proxy can be forwarded to the second CDN. This provides a
secure means of enabling a media URL generated by a content service
provider to be used in a different manner to that originally
intended by the content service provider, as long as it is supplied
via a user terminal that is trusted by the content service
provider
[0064] The user terminal has installed in its. operating system a
data file including an authentication certificate file, and
operating instructions to configure the user terminal to operate
accordingly.
[0065] The invention causes re-direction of a media request,
initially addressed to a first content delivery network, so as to
be redirected to a second content delivery network, in which use of
a proxy server is controlled by a request redirection process, and
the proxy performs a mutual authentication process with the user
terminal to ensure that it is only accessible via legitimate
trusted user terminals which are known to be secure. The proxy
generates a new media asset locator pointing at the second content
delivery network, derived from the initial media access location,
and can also be used to increase the strength of any access
constraints e.g. to identify the accession attempt as coming from
an authorised user.
[0066] The invention in our copending application entitled "Data
Retrieval Redirection" provides a method of operating an asset
location request redirection system in which a user terminal
redirects first asset location data relating to a first content
delivery network to a redirection server which generates second
asset location data such that the asset location request is
directed to a second content delivery network, wherein the
redirection server, on receiving the first media asset location
request data generates a signed second asset location for
transmission to the second content delivery network, and the second
content delivery network uses data in the signed second asset
location to determine whether the asset location request is to be
met. Another aspect of the invention provides a redirection server
having a receiver for receiving first media asset location request
data from a user terminal , a redirection processor for generating
a second asset location, and a transmitter for transmitting the
second asset location to the user terminal , wherein the
redirection server comprises an authentication processor to
generate a signature for inclusion with the asset location.
[0067] This co-pending invention allows a request for media to be
securely re-directed, such that any access restrictions applied to
the original media are preserved, and can additionally be
strengthened as required by the network service provider. This
invention protects against use of the redirection server as a way
of bypassing validation of signatures provided e.g using the
processes as described with reference to U.S. Pat. No. 5,805,803
and EP1278112. By use of a mutually authenticated SSL (secure
sockets layer) or TLS (transport layer security) connection, it can
be ensured that the second content delivery, server only accepts
valid requests, signed by the redirection server, and cannot be
compromised by any action taken at the user terminal. The asset
location request may be passed from the redirect server by way of
the user's client player, but the user is not given the necessary
information to read the request, or generate a request which can be
accepted by the second content delivery server. The invention also
enables the use of IP signatures in a Carrier Grade NAT environment
where the public IP address seen by the content provider is
different from the private IP address seen by the Internet Service
Provider's CDN. Preferably, the signed asset location includes a
timestamp to determine an expiry period (or start/end time range)
for the media asset location request, and an address identifying a
legitimate user terminal, to confirm that the request has not been
stored or transferred to another user terminal. The media asset
location data generated by the proxy redirection server may include
device-specific data configured according to the user terminal from
which the request for data is received. The signed second asset
location may include an address restriction specifying a network
address from which the asset may be accessed. This allows the
second content delivery network to confirm that the request has not
been stored or transferred to another user terminal. This enables a
strengthening of the access restrictions associated with the asset,
and protecting the interests of the network service provider over
which the media asset is to be retrieved, as well as the interests
of the content service provider which issued. the original asset
location. It therefore ensures that any media asset location sent
to the second content delivery network as a result of the
redirection request cannot be used to access expired material
remaining in the second content delivery platform.
[0068] In the preferred embodiment of the copending invention, the
user terminal has a Client Proxy Configuration installed, to
redirect requests to the secure proxy server in response to
requests for data from specified media servers. Following a request
for data from an internet address (universal resource locator--URI)
associated with the first CDN, the secure proxy constructs a new
URI and signature that is appropriate for the second CDN, and sends
this back to the client via a redirection response, containing a
signed URI, for example, an HTTP redirection response. The user
terminal then uses this URI and signature, to access the required
data from the second media server. The secure proxy only accepts
requests from trusted authenticated clients, so it is not possible
for a rogue client to use the proxy to bypass the original media
server's URI signature. The proxy can be used to enhance the
service, for example by increasing the strength of the signature
e.g. from time-bound only, to add a requirement for a client IP,
and can also be used to enable use of IP signatures in a Carrier
Grade NAT (network address translation) environment, as will be
described later.
[0069] Many Content Service Providers operate media selectors which
return a URI based on a secure scheme, such as https. Conventional
user terminal software handles secure data that is to be
transmitted to a proxy server by attempting to set up a secure
tunnel to the specified location via the proxy, so that only the
user and the specified location have access to the secure data, and
it is not visible to the proxy server itself (See FIG. 10, tunnel
181). However, such an arrangement would not be suitable if the
proxy is required to process media asset location requests and
issue re-direct responses, as the secure connection would prevent
the proxy redirect server from reading the media asset request, or
doing anything with it other than forward it to the specified
URI.
[0070] This problem may be avoided by reconfiguring the user
terminal software according to the invention in our other copending
application entitled "Proxy Server Operation", in which a
communications terminal having a message compiler for transmitting
data to predetermined addresses, having a secure connection means
for transmitting data having a secure data location address to set
up a secure tunnel to the address, and characterised in having a
discriminator for identifying media access location data
identifying a pre-defined set of known media servers, and second
connection means for transmitting media access location data
addressed to a secure location server specified by the media access
locator, by way of a proxy, without setting up a tunnel whereby
secure media access locators are passed to the proxy over a
connection between the user terminal and the proxy for redirection
by the proxy server.
[0071] In another aspect the invention provides a method for
routing data messages having secure data location addresses wherein
data having a secure data location address, other than media access
locators, are transmitted from a user terminal by way of a proxy
server by setting up a secure tunnel, by way of the proxy, to a
server specified by the media access locator, and characterised in
that secure media access locators identifying a pre-defined set of
known media servers are passed to a proxy server over a connection
between the user terminal and the proxy such that the proxy server
may generate a redirected media access locator for return to the
user terminal.
[0072] The connection between the user terminal and the redirection
server may be provide by a mutually authenticated connection, The
user terminal may be configured by transmitting a downloadable data
file to the device for installation on the device, the downloadable
data file including operating instructions to configure the device
to operate according to the invention. As indicated above, the
connection between the user terminal and the redirection server may
itself be a mutually authenticated connection,
[0073] An embodiment of the invention will now be described, with
reference to the drawings, in which:
[0074] FIG. 1 is a schematic depiction of a conventional content
delivery system, and has already been discussed
[0075] FIG. 2 is a schematic depiction of the various elements
which co-operate to perform the invention.
[0076] FIG. 3 is a sequence diagram illustrating the processes
performed by these elements according to the invention.
[0077] FIG. 4 is a schematic diagram illustrating the functional
elements of the redirection server in more detail
[0078] FIG. 5 is a schematic diagram illustrating the functional
elements of a client player configured to operate according to the
invention, and illustrates the configuration process itself.
[0079] FIG. 6 is a schematic diagram illustrating the functional
elements of a client player configured to operate according to the
invention, and illustrates a first redirection step
[0080] FIG. 7 is a schematic diagram illustrating the functional
elements of a client player configured to operate according to the
invention, and illustrates a second redirection step
[0081] FIG. 8 is a schematic diagram illustrating the functional
elements of a client player configured to operate according to the
invention, illustrating a display step.
[0082] FIG. 9 illustrates a system in which carrier grade network
address translation is in use.
[0083] FIG. 10 illustrates a conventional connection between a user
terminal and a proxy server when conveying secure data.
[0084] FIG. 1 and FIG. 2 both depict a user terminal 11 connectable
to an access service network 12 such as the "Internet". The user
terminal 11 can be a general purpose computer or a dedicated media
terminal, and may be embodied in two or more intercommunicating
devices. Among its functions, typically embodied in software, are a
browser 13 for accessing data, a media player 14 for downloading
video or audio streamed data, and an output 19 for displaying the
data. In most practical applications all these devices would share
the same connection to the Internet 12.
[0085] FIGS. 1 and 2 also depict several functions operated by
service providers and accessible from the user equipment 11 over
the data network 12.
[0086] In the prior art system of FIG. 1 there is depicted a media
selector platform 15 and a content delivery network 160, comprising
a number of content delivery servers 160, which store content for
download to users on request.
[0087] These platforms derive this content from an Original Content
Server 16, which they access as required if the content is not
already stored on the individual server 160. The media selector
platform 15 provides a listing, indexing or cataloguing function,
and identifies the Internet address (URI) of content stored in the
Original Content Server 16 for access by the user. These functions
are typically under the control of the content service
provider.
[0088] The process followed by this equipment is illustrated in
FIG. 1. In order to access viewable material, a user uses the
browser 13 to access a content catalogue of available material,
searchable for example by genre, title, date made available, etc,
from which the user may select a item. Once the item is selected,
the media selector 15 is invoked by the browser 13 to obtain a
media asset location URI for that item. The platform 15 returns a
message to the browser 13 identifying the media asset location for
the selected content, in the form of a URI (step 22).
[0089] The browser 13 forwards the media asset location to the
media player 14 (step 23). In a conventional system the client
player then transmits a request 260 to the first delivery platform
16 hosted by the original content provider, using the. URI in the
media asset location message. The delivery platform 16 uses the
media asset location to determine the content to be delivered,
which it then returns to the media player 14 (step 280) for display
19 (step 29). If the media asset location data is not valid the
delivery platform returns an error message. Reasons for such
invalidity may include time expiry--the content is no longer
available for access. This prevents users from storing media asset
location codes, or sharing them with other users, for later
access.
[0090] As already described, accessing a media delivery platform 16
over a standard data connection causes some difficulties, and there
may be benefits to a network service provider hosting its own
content delivery platform 17. FIG. 2 depicts an arrangement using
such a secondary content delivery server 17 which, like the content
delivery servers forming the primary content delivery network 160,
can also download content to users on request, either by retrieving
such content from the Original Content Server 16, or from a cache
176 of data that has previously been so retrieved. FIG. 3 is
sequence diagram illustrating the processes operated by this
system.
[0091] Data is downloaded from the originator's delivery platform
16 once (step 27), (e.g. in response to the first customer request
for it) and subsequently re-used for any subsequent requests. As
the platform 17 is typically much nearer the customer terminal 11,
the network capacity required for delivery is reduced.
[0092] To encourage use of the platform 17, operators may exempt
downloads 28 from the platform 17 from counting towards the
customer's usage limit. Techniques such as prioritisation of
streamed data are also possible when the network operator has
end-to-end control of the download 28 between the delivery platform
17 and user media player 14.
[0093] It is desirable to limit access to this second content
delivery server 17 to a specified category of users, so that other
users are directed to the default network 160 provided by the
content service provider. It is also desired to achieve this
without modification to the content service provider's own service
platform 15, 16. This is achieved this by using a redirection
process mediated by a redirection server 18. The process is made
subject to a validation process, typically under the control of a
service provider, with whom the user 11 has a trusted (validated)
relationship.
[0094] In order to access the platform 17, the media player 14 of
an authorised terminal 11 is configured to convert any media asset
location code it receives so that the request is handled by the
platform 17 instead of the originator's platform 16. In practice
this is done using a redirection server 18, which provides a
concordance between the address of the original content platform 16
and the address of the content platform 17. (For load balancing
purposes and other reasons this concordance may vary over time, so
the user terminal 14 cannot do the translation itself).
[0095] The functional elements of the redirection server 18 are
illustrated in more detail in FIG. 4. It should be understood that
these elements may be embodied in software running on a general
purpose computer.
[0096] The redirection server 18 has an input 30 for receiving
redirection requests 24 from a user terminal 14 which has been
configured (through an installed application 140) to identify
requests addressed to the primary content delivery network 160 and
to transmit them instead to the redirection server 18. The
redirection server comprises a reader 31 for identifying the
requested domain name, a retrieval system 32 for retrieving a
corresponding proxy domain name from a concordance store 33, a
message generator 34 for embodying the retrieved domain name in a
new message for return to the client 14 through an output 38.
Further features 35, 36, 37 of FIG. 4 will be described later.
[0097] It would be possible for a user to pass a URI received from
the redirection server 18 to other, unauthorised users (not
subscribers to the service provider hosting the delivery platform
17), allowing them to also access content from the delivery
platform 17. Moreover, a user could store the uri to allow multiple
accessions of the same stream from the delivery platform 17.
Furthermore, the platform 17 does not have visibility of the time
stamp data, controlling access to the primary content platform 16,
so out-of-date content may remain on the platform 17 after it has
ceased to be available from the originator's own service, or has
been modified, which would allow a user who has stored the uri to
continue to retrieve it.
[0098] Such delayed accessions are undesirable for the original
content provider, who would lose control of distribution of the
content itself, for instance if the information becomes out of
date, or has to be withdrawn for legal reasons. Multiple accessions
of the delivery platform 17, without each requiring an initial
interaction 21, 22 with the content provider's own platform 15,
would also result in the content provider losing information on
viewing statistics, which has implications for programme popularity
ratings, royalties due to the copyright owners and performers,
etc.
[0099] Unauthorised access by users not subscribing to the service
provided by the delivery platform server 17 would also, result in a
loss of revenue to the service provider.
[0100] To avoid these difficulties, a process will now be described
which allows verification of both the identity of the user and the
validity of the original media asset location code. The interaction
24, 25 between the user media player 14 and the redirection server
18 is subject to an authentication process 35, 36. This will be
referred to as mutual authentication because the client and server
are both required to prove their authenticity to each other. In
particular, the client (user terminal 11) is required to prove to
the redirection server 18 that it is authorised to have access to
the secondary content delivery platform 17. It can be arranged such
that the necessary configuration software to access the redirection
server 18 includes a public key certificate and a "private" key,
wherein the public key certificate can be checked for authenticity
by a "public" certification authority key stored in the redirection
server 18 for use by the validity checker 35.
[0101] In order to achieve this, a proxy configuration 140 is
installed in the client player device 14. This configuration can be
installed by any suitable secure means, typically by being "burnt
in" to the device on manufacture. However, a download from the
service provider may be possible if a secure means of doing so is
available as will be discussed with reference to FIG. 5. Provided
that the service provider has control of the installation of this
configuration 140, its presence on the device 14 is confirmation
that the device is authorised to access the redirection processor
18.
[0102] The functional, elements of the client player 14, as
configured by the proxy configurator 140, are illustrated in FIGS.
5 to 8, which together illustrate the various information flows
that take place. The various components are an input 40, an output
45, a processor 41 for handling incoming messages, a redirection
store 42 for maintaining a concordance of redirection addresses, a
certification store 43 for maintaining an authenticity certificate,
a message compiler 44 for assembling outgoing messages, a streaming
compiler 46 for processing streamed content, including
decompression, buffering and other functions, and a central
processor 47 for co-ordinating the operation of the other functions
40-46.
[0103] The configuration process itself may be performed by
software installed in the client player 14 on manufacture or, as
illustrated in FIG. 5, by download from a storage medium such as a
magnetic disc, or from a technician's computer during a site visit,
or by download over the internet from a site managed by the service
provider.
[0104] The download 20 is delivered through an appropriate input
device 40 and installed on the CPU 47, which stores the appropriate
redirection instructions and certificate in the respective stores
42, 43. Downloading may also be used to update subscriber details,
for example to renew a certificate to confirm payment of a
subscription for the service.
[0105] The certificate 43 can be used for other purposes in
addition to the redirection process 42, and the two elements do not
necessarily have to both be loaded as part of the same process. So
for example the certificate 43 might be burned in on manufacture,
whilst the proxy configuration 42 might be downloaded as part of a
user terminal software upgrade at a later stage, using the process
illustrated in FIG. 6.
[0106] As shown in FIG. 6, in operation, when a user makes an input
21 through the browser 13 to the media selector 15 to request an
item of media content, the media selector returns a media asset
location 22 to the browser which forwards it to the media player 14
(step 23). The incoming message processor 41 reads the media asset
location and, under the control of the redirection address function
42 (which has been programmed by the configuration 140) determines
if the media asset location address 23 meets predetermined criteria
identifying it as suitable for redirection. If the media access
location is so identified, the compiler 44 incorporates it in a
message 24, to be forwarded via the output 45 to the proxy
redirection server 18.
[0107] Before the message 24 can be sent, a secure connection has
to be created between the user terminal 11 and the proxy
redirection server 18. The redirection server 18 has a validity
checking system 35 operating in parallel with the redirection
processor 31-33. The mutual authentication process 24 involves the
transmission by each party of a "public key certificate": a data
string including identification details, including the public key,
together with a copy of the same data, or a string derived from it,
which has been encrypted by a trusted third party certification
authority's private key. Each party can thus use the public key in
the certificate itself to verify that the certificate originates
from the owner of the respective private key.
[0108] If. the check 35 identifies the presence of a valid
certificate, an authentication processor 36 permits redirection
data requests to be processed (31-33) and applies a signature to
the redirection messages compiled in the message generator 34,
together with a time stamp 37, and transmits it back to the
requesting device through the output 38. Alternative messages may
be generated if the validity check fails.
[0109] Public key certificates are used for the purpose of
verifying the identity of the client (by the redirection server)
and the redirection server (by the client). This is done at the
connection-establishment stage, which creates a secure
mutually-authenticated channel for subsequent communication of a
media request.
[0110] Digital signatures are used to protect the media asset
locators 22, 26, that are returned by both the primary CDN 21 and
the proxy. server 18. The media asset locators contain information
such as a time expiry and/or IP address restriction which cannot be
tampered with. The signature ensures that any attempt to tamper
with the media asset locator will be detected, enabling rejection
of that media asset locator as invalid.
[0111] The user terminal may be accessed by Carrier Grade Network
Address Translation (CGNAT). CGNAT is a widely used method of
coping with the exhaustion of the IPv4 (32-bit) address space, as
an interim measure during the transition to IPv6 (128-bit
addresses). It provides each client with a public IPv4 address
shared with several other clients of the same service provider, but
they each also have a Separate "private" IP address for use within
the network of the service provider for distribution of data to its
own individual subscribers. FIG. 9 is a schematic depiction of an
interface between a service provider's own network 12 and the
public network 120.
[0112] The translation between public and private URIs takes place
at the interface 121 between the service provider's own network 12
and the rest of the network 120. Only the public IP address is
visible to external parties, and the private IP address is only
visible to the local network. Thus, the external media selector 15
would authenticate the user's public URI, which is shared with many
other users, but the URI subsequently presented to the secondary
media server 17, provisioned by the service provider, would use the
private IP. The proxy redirection solution with re-signing avoids
this difficulty, because the redirection server 18 generates a new
signature (authentication) of the request using the private IP
address which is subsequently presented to the media server 17.
[0113] This facility also allows the invention be used to enable a
small Internet service provider, or a small private network such as
a hotel or small business, to provide access to content specific to
its users using an externally hosted content provider. Access to
the redirection server 18 is only possible from user terminals
having the corresponding proxy configuration 140 installed, and
only requests authenticated by the redirection server 18 are
accepted by the media platform 17. A service provider may host
multiple content delivery platforms 17, each only accessible by
user terminals 11 having the appropriate respective configuration
141 allowing authentication using a respective redirection and
authentication server 18.
[0114] A difficulty can arise if the Content Provider operates a
media selector 15 which returns a Media Access Locator 22 that
specifies a secure scheme e.g. the URI is in "https" format.
Content providers do this to ensure that the connection between the
user 11 and content delivery server 16, 170 is secure. As shown in
FIGS. 6 and 10, conventional user terminal software handles secure
(https) data that is to be transmitted via a proxy server (18) by
attempting to set up a secure "tunnel" 181 between the user
terminal 11 and the specified location via the proxy 18, so that
the only the user and the specified location have access to the
secure data. For a secure (https) address, the message compiler 44
would generally set up a secure link 181 between the user terminal
and the address specified, (tunnel generation function 441) to be
routed by way of the specified proxy. Referring again to FIG. 2,
the media access locator 251 would therefore not be visible to the
proxy server 18 itself. Such an arrangement would not be suitable
if the proxy is required to redirect the media asset location
request 251, as the secure connection 181 would prevent the proxy
redirect server from reading the media asset request, or doing
anything with it other than forward it to the specified URI 16.
However, for present purposes the proxy must be able to read the
media asset location 251 in order to generate the redirected media
asset location 26.
[0115] This problem may be avoided by configuring the user terminal
client player 14 (FIG. 6) so that the incoming message processor 41
includes a discrimination function 411 which identifies incoming
asset location addresses 23 arriving from a specified source (media
asset location server 15), or of a specified type (e.g locations
for media assets) and directs the message compiler 44 to handle
such requests by setting up a secure connection only between the
user terminal 14 and the redirect server 18, so that the redirect
server 18 can process the request 251 passed over the connection.
For such media access location requests, the tunnel starting at the
user terminal 11 therefore terminates at the proxy server 18.
However, the user terminal is arranged so that secure media access
locators 251 are passed on to the proxy redirection 18 via a
mutually authenticated channel that is based on the identity of the
proxy redirection itself, as opposed to the identity of the CDN
server 18 identified by the Media Access Locator 251. This differs
from typical client device behaviour when proxying https requests,
which usually entails setting up a secure tunnel 181 to the
destination server via-the proxy 18, such that the proxy 18 is
unable to decrypt the contents. The user terminal 11 handles secure
data location addresses that are to be handled by a proxy server,
other than media access locators, by setting up a secure tunnel 181
to a server specified by the media access locator, by way of the
proxy 18, in the usual way.
[0116] Referring again to FIGS. 2 and 3, the secure redirection
server 18 assesses the incoming media asset location address (URL)
251, constructs a new URI and signature that is appropriate for the
content delivery network 17, and sends this back to the client 14
using a redirection response 26. The secure redirection server 18
only accepts requests from trusted authenticated clients which have
satisfied the authentication process 24, so it is not possible for
a rogue client to use the proxy to bypass the original media
server's URI signature.
[0117] The redirection server 18 checks the authentication
certificate, (e.g. by applying a public key to decrypt the
certificate sent by the client player). Authentication messages
that will be recognised by the validity checker 35 in the
redirection server 18 can only be generated by a client player 14
having a valid certificate 43 installed so, provided the network
operator maintains control of the installation process for the
configuration application 140, the operator can be sure that any
Client player 14 generating authentication messages 24 is doing so
under the operator's authority.
[0118] The proxy name retrieval system 32 creates a new address URI
by substituting the domain name of the original media source 15 by
that of the delivery platform 17, also providing a signature and
time, stamp or other authentication data which is verifiable by the
media player 17. The new details are returned to the client player
14 (step 25). To avoid tampering by the user terminal 11, a secure
connection is set up between the redirect server 18 and the
secondary content server 17, and the redirect request 26, 252
tunnelled directly to the secondary content server 17, including an
instruction to return the requested content 28 to the client player
14 from which the original request 251 was received.
[0119] Referring now to FIG. 7, the client player 20 receives the
new media asset request data 25 (which, as indicated above, carries
a signature that can only be validated by the secondary content
server, so the user of the terminal 11 cannot read it directly, or
tamper with it) and compiles it into a new message 26 to be sent to
the platform 17, carrying the details in the data 25 received from
the redirection server 18. This ensures that the secondary content
delivery server 17 only receives media requests 252 that have been
recently generated by the redirect server 18.
[0120] Referring once again to FIGS. 2 and 3, the platform 17
checks the time stamp and other authentication data in the media
request 26 it receives from the client player 14. The
authentication data provides proof that the client player making
the request has had the proxy configuration 140 installed. Since
download of this configuration is under the control of the service
provider, the necessary authentication 24 will only be present if
the service provider has authorised the client player to use the
service.
[0121] The media location request 24 also includes a time stamp.
This is checked by the platform 17 to ensure that the request 26
was generated in response to a very recent response from the media
selector 12, and thus that the data requested has not been
withdrawn by the original data provider 16. This ensures that each
accession through the platform 17 is made in response to an
original request made to the host media selector 15, allowing the
original provider to retain an overview of all such requests, and
to control access to the data.
[0122] In particular time-expired media assets cannot be accessed:
if a user 14 attempts to use a stored copy of the new media asset
locator held in the redirected request 26 the asset locator 24, the
redirection server 17 will reject it as time expired. If the user
attempts to generate a new redirection message, by using the
browser to connect with the media selector platform 15 associated
with the media asset's originator, the request will be rejected
because the service provider has disabled access to that
content.
[0123] Moreover, the requests 24, 26 cannot be copied and used by
unauthorised client players because they are unable to be
authenticated for connection to the proxy redirection server 17 and
content delivery platform 18, as they do not have the private key
held in. the proxy configuration 140. If the authentication details
are verified, the delivery platform 17 first checks the data cache
176 to determine if the requested media data file is present in the
cache (step 270), and retrieves it from the cache if it is present
(step 271). However, if this is the first request for that resource
material, and it is therefore not already present in the cache, the
platform 17 sources the asset from the original source 16 (step
27). As well as delivering the data to the user terminal 14 (step
271), the platform also stores a copy in its data cache 176 for
easier retrieval in response to subsequent requests.
[0124] As described above, it is also possible to modify the
content to be transmitted in response to requests, for example by
removing material, replacing it with material tailored to
individual user interests, geographical factors, etc, or providing
value-added content such as subtitles to the original material.
This could be achieved by extracting and modifying the relevant
material for storage in the cache 176 before any request has been
made for it. Different versions may be made available for different
data connections 12, client player types 14 or outputs 19,
identifiable to the proxy redirection server from the user
identity, which can thus be used to select the appropriate
redirection message for the appropriate version of the content
required.
[0125] The media data file identified by the delivery platform
player 17 as corresponding to the request 26 is then returned (step
28) to the client player 14. As shown in FIG. 8, the content is
passed to the streaming processor 46, which processes the streamed
content for output (step 29) on a device 19 such as a television
set. The processing performed by the processor 46 will depend on
the nature of the output display 19. Furthermore, the proxy
configuration 140 may be arranged to cause the requests 26 it
generates to be configured to request content in a form suitable
for the particular output device 19. For example, if the user
device 11 is a general purpose computer, the internet connection 12
has a high bandwidth, and the output is a high definition
television 19, a high definition, high bandwidth data stream can be
requested. In contrast, if the user device 11 is a small portable
device, with a low definition monochrome output 19, and connected
to the internet 12 over a low bandwidth wireless connection, a
lower bandwidth data stream with less definition would be
appropriate. The ordering processor 17 would be arranged to
configure the data stream 28 in accordance with the details of the
request 26.
[0126] Note that platforms 16, 17 may both retain media data for a
period after requests 21 for that data cease to be valid. This
allows users currently viewing content at the time of expiry of
availability of that to complete their downloading and viewing of
that content. Furthermore, the second platform 17 would not
generally be informed by the owner of the primary content delivery
platform 16 of the expiry or modification of the data in its cache
176. (The secondary platform "pulls" data from the primary
platform--there is no "push" of data by the primary platform). In
practice the data is retained in the cache until a specified time
has elapsed with no accessions having been made, or until it needs
to be overwritten to accommodate a more recent download. The
present invention prevents out-of-date data being accessible from
the cache 176, because no accessions can be made to such data from
the cache 176, except in response to a request using a valid
timestamp. The proxy configuration 140 in the client player 14 will
only issue such a timestamp in response to a successful response
22, 23 being received from the media selector 15.
[0127] As will be understood by those skilled in the art, the
invention may be implemented in computer program product software,
any or all of which may be contained on various storage media so
that the program can be loaded onto one or more general purpose
computers or downloaded over a computer network using a suitable
transmission medium. The computer program product used to implement
the invention may be embodied on any suitable carrier-, readable by
a suitable computer input device, such as optically readable media
and magnetic media.
* * * * *