draft-ietf-ipdvb-sec-req-04.txt   draft-ietf-ipdvb-sec-req-05.txt 
IPDVB Working Group H. Cruickshank
Internet Engineering Task Force H. Cruickshank Internet-Draft S. Iyengar
Internet-Draft University of Surrey, UK Intended status: Informational University of Surrey, UK
Intended status: Informational S. Iyengar
Expires: March 8, 2008 University of Surrey, UK
P. Pillai P. Pillai
University of Bradford, UK Expires: April 12, 2008 University of Bradford, UK
October 11, 2007 November 18, 2007
Security requirements for the Unidirectional Lightweight Security requirements for the Unidirectional Lightweight
Encapsulation (ULE) protocol Encapsulation (ULE) protocol
draft-ietf-ipdvb-sec-req-04.txt draft-ietf-ipdvb-sec-req-05.txt
Status of this Draft Status of this Draft
By submitting this Internet-Draft, each author represents that By submitting this Internet-Draft, each author represents that
any applicable patent or other IPR claims of which he or she is any applicable patent or other IPR claims of which he or she is
aware have been or will be disclosed, and any of which he or she aware have been or will be disclosed, and any of which he or she
becomes aware will be disclosed, in accordance with Section 6 of becomes aware will be disclosed, in accordance with Section 6 of
BCP 79. BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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documents at any time. It is inappropriate to use Internet- documents at any time. It is inappropriate to use Internet-
Drafts as reference material or to cite them other than as "work Drafts as reference material or to cite them other than as "work
in progress." in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on March 8, 2007. This Internet-Draft will expire on May 12, 2008.
Abstract Abstract
The MPEG-2 standard defined by ISO 13818-1 supports a range of The MPEG-2 standard defined by ISO 13818-1 supports a range of
transmission methods for a range of services. This document transmission methods for a range of services. This document
provides a threat analysis and derives the security requirements provides a threat analysis and derives the security requirements
when using the Transport Stream, TS, to support an Internet when using the Transport Stream, TS, to support an Internet
network-layer using Unidirectional Lightweight Encapsulation network-layer using Unidirectional Lightweight Encapsulation
(ULE) defined in RFC4326. The document also provides the (ULE) defined in RFC4326. The document also provides the
motivation for link-layer security for a ULE Stream. A ULE Stream motivation for link-layer security for a ULE Stream. A ULE Stream
may be used to send IPv4 packets, IPv6 packets, and other may be used to send IPv4 packets, IPv6 packets, and other
Protocol Data Units (PDUs) to an arbitrarily large number of Protocol Data Units (PDUs) to an arbitrarily large number of
Receivers supporting unicast and/or multicast transmission. Receivers supporting unicast and/or multicast transmission.
Table of Contents Table of Contents
1. Introduction................................................2 1. Introduction................................................2
2. Requirements notation.......................................4 2. Requirements notation.......................................4
3. Threat Analysis.............................................6 3. Threat Analysis.............................................6
3.1. System Components......................................6 3.1. System Components......................................6
3.2. Threats................................................8 3.2. Threats................................................9
3.3. Threat Scenarios......................................10 3.3. Threat Scenarios......................................10
4. Security Requirements for IP over MPEG-2 TS................11 4. Security Requirements for IP over MPEG-2 TS................11
5. Motivation for ULE link-layer security.....................13 5. Motivation for ULE link-layer security.....................13
5.1. Security at the IP layer (using IPSEC)................13 5.1. Security at the IP layer (using IPSEC)................13
5.2. Link security below the Encapsulation layer...........14 5.2. Link security below the Encapsulation layer...........14
5.3. Link security as a part of the encapsulation layer....15 5.3. Link security as a part of the encapsulation layer....15
6. Design recommendations for ULE Security Header Extension...15 6. Design recommendations for ULE Security Header Extension...16
7. Compatibility with Generic Stream Encapsulation............16 7. Compatibility with Generic Stream Encapsulation............17
8. Summary....................................................17 8. Summary....................................................17
9. Security Considerations....................................18 9. Security Considerations....................................18
10. IANA Considerations.......................................18 10. IANA Considerations.......................................18
11. Acknowledgments...........................................18 11. Acknowledgments...........................................18
12. References................................................18 12. References................................................19
12.1. Normative References.................................19 12.1. Normative References.................................19
12.2. Informative References...............................19 12.2. Informative References...............................19
13. Author's Addresses........................................20 13. Author's Addresses........................................21
14. IPR Notices...............................................21 14. IPR Notices...............................................21
14.1. Intellectual Property Statement......................21 14.1. Intellectual Property Statement......................21
14.2. Intellectual Property................................21 14.2. Intellectual Property................................22
15. Copyright Statement.......................................22 15. Copyright Statement.......................................22
Appendix A: ULE Security Framework............................22 Appendix A: ULE Security Framework............................22
Document History..............................................26 Document History..............................................28
1. Introduction 1. Introduction
The MPEG-2 Transport Stream (TS) has been widely accepted not The MPEG-2 Transport Stream (TS) has been widely accepted not
only for providing digital TV services, but also as a subnetwork only for providing digital TV services, but also as a subnetwork
technology for building IP networks. RFC 4326 [RFC4326] describes technology for building IP networks. RFC 4326 [RFC4326] describes
the Unidirectional Lightweight Encapsulation (ULE) mechanism for the Unidirectional Lightweight Encapsulation (ULE) mechanism for
the transport of IPv4 and IPv6 Datagrams and other network the transport of IPv4 and IPv6 Datagrams and other network
protocol packets directly over the ISO MPEG-2 Transport Stream as protocol packets directly over the ISO MPEG-2 Transport Stream as
TS Private Data. ULE specifies a base encapsulation format and TS Private Data. ULE specifies a base encapsulation format and
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employ end-to-end network security mechanisms like IPSec or employ end-to-end network security mechanisms like IPSec or
Transport Layer Security (TLS). Governmental users may be forced Transport Layer Security (TLS). Governmental users may be forced
by regulations to employ specific, approved implementations of by regulations to employ specific, approved implementations of
those mechanisms. Hence for such cases the confidentiality and those mechanisms. Hence for such cases the confidentiality and
integrity of the user data will already be taken care of by the integrity of the user data will already be taken care of by the
end-to-end security mechanism and the ULE security measures would end-to-end security mechanism and the ULE security measures would
focus on either providing traffic flow confidentiality for user focus on either providing traffic flow confidentiality for user
data that has already been encrypted or for users who choose not data that has already been encrypted or for users who choose not
to implement end-to-end security mechanisms. to implement end-to-end security mechanisms.
ULE links may also be used for communications where the two end-
points are not under central control (e.g., when browsing a
public web site). In these cases, it may be impossible to enforce
any end-to-end security mechanisms. Yet, a common objective is
that users can rely on security assumptions as of wired links.
ULE security could achieve this by protecting the vulnerable (in
terms of passive attacks) ULE link.
In contrast to the above, if a ULE Stream is used to directly In contrast to the above, if a ULE Stream is used to directly
join networks which are considered physically secure, for example join networks which are considered physically secure, for example
branch offices to a central office, ULE link Security could be branch offices to a central office, ULE link Security could be
the sole provider of confidentiality and integrity. In this the sole provider of confidentiality and integrity. In this
scenario, governmental users could still have to employ approved scenario, governmental users could still have to employ approved
cryptographic equipment at the network layer or above, unless a cryptographic equipment at the network layer or above, unless a
manufacturer of ULE Link Security equipment obtains governmental manufacturer of ULE Link Security equipment obtains governmental
approval for their implementation. approval for their implementation.
3.2. Threats 3.2. Threats
The simplest type of network threat is a passive threat. This The simplest type of network threat is a passive threat. This
includes eavesdropping or monitoring of transmissions, with a includes eavesdropping or monitoring of transmissions, with a
goal to obtain information that is being transmitted. In goal to obtain information that is being transmitted. In
broadcast networks (especially those utilising widely available broadcast networks (especially those utilising widely available
low-cost physical layer interfaces, such as DVB) passive threats low-cost physical layer interfaces, such as DVB) passive threats
are considered the major threats. An example of such a threat is are considered the major threats. An example of such a threat is
an intruder monitoring the MPEG-2 transmission broadcast and then an intruder monitoring the MPEG-2 transmission broadcast and then
extracting traffic information concerning the communication extracting traffic information concerning the communication
between IP hosts using a link. Another example is of an intruder between IP hosts using a link. Another example is of an intruder
trying to gain information about the communication parties by trying to gain information about the communication parties by
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3.3. Threat Scenarios 3.3. Threat Scenarios
Analysing the topological scenarios for MPEG-2 Transmission Analysing the topological scenarios for MPEG-2 Transmission
Networks in section 1, the security threat cases can be Networks in section 1, the security threat cases can be
abstracted into three cases: abstracted into three cases:
o Case 1: Monitoring (passive threat). Here the intruder o Case 1: Monitoring (passive threat). Here the intruder
monitors the ULE broadcasts to gain information about the ULE monitors the ULE broadcasts to gain information about the ULE
data and/or tracking the communicating parties identities (by data and/or tracking the communicating parties identities (by
monitoring the destination NPA). In this scenario, measures monitoring the destination NPA). In this scenario, measures
must be taken to protect the ULE data flow and the identity of must be taken to protect the ULE payload data and the identity
ULE Receivers. of ULE Receivers.
o Case 2: Locally conduct active attacks on the MPEG-TS o Case 2: Locally conduct active attacks on the MPEG-TS
multiplex. Here an intruder is assumed to be sufficiently multiplex. Here an intruder is assumed to be sufficiently
sophisticated to over-ride the original transmission from the sophisticated to over-ride the original transmission from the
ULE Encapsulation Gateway and deliver a modified version of ULE Encapsulation Gateway and deliver a modified version of
the MPEG-TS transmission to a single ULE Receiver or a small the MPEG-TS transmission to a single ULE Receiver or a small
group of Receivers (e.g. in a single company site). The MPEG-2 group of Receivers (e.g. in a single company site). The MPEG-2
transmission network operator might not be aware of such transmission network operator might not be aware of such
attacks. Measures must be taken to ensure ULE source attacks. Measures must be taken to ensure ULE source
authentication and preventing replay of old messages. authentication and preventing replay of old messages.
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o Case 3: Globally conduct active attacks on the MPEG-TS o Case 3: Globally conduct active attacks on the MPEG-TS
multiplex. Here we assume an intruder is very sophisticated multiplex. Here we assume an intruder is very sophisticated
and able to over-ride the whole MPEG-2 transmission multiplex. and able to over-ride the whole MPEG-2 transmission multiplex.
The requirements here are similar to scenario 2. The MPEG-2 The requirements here are similar to scenario 2. The MPEG-2
transmission network operator can usually identify such transmission network operator can usually identify such
attacks and may resort to some means to restore the original attacks and may resort to some means to restore the original
transmission. transmission.
For both cases 2 and 3, there can be two sub cases: For both cases 2 and 3, there can be two sub cases:
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o Insider attacks i.e. active attacks from adversaries in the o Insider attacks i.e. active attacks from adversaries in the
known of secret material. known of secret material.
o Outsider attacks i.e. active attacks from outside of a virtual o Outsider attacks i.e. active attacks from outside of a virtual
private network. private network.
In terms of priority, case 1 is considered the major threat in In terms of priority, case 1 is considered the major threat in
MPEG-2 transmission systems. Case 2 is likely to a lesser degree MPEG-2 transmission systems. Case 2 is likely to a lesser degree
within certain network configurations, especially when there are within certain network configurations, especially when there are
insider attacks. Hence, protection against such active attacks insider attacks. Hence, protection against such active attacks
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assumption being here is that physical access to the network assumption being here is that physical access to the network
components (multiplexers, etc) and/or connecting physical media components (multiplexers, etc) and/or connecting physical media
is secure. Therefore case 3 is not considered further in this is secure. Therefore case 3 is not considered further in this
document. document.
4. Security Requirements for IP over MPEG-2 TS 4. Security Requirements for IP over MPEG-2 TS
From the threat analysis in section 3, the following security From the threat analysis in section 3, the following security
requirements can be derived: requirements can be derived:
o Data flow confidentiality is the major requirement to mitigate o Data confidentiality is the major requirement to mitigate
passive threats in MPEG-2 broadcast networks. passive threats in MPEG-2 broadcast networks.
o Protection of Layer 2 NPA address. In broadcast networks this o Protection of Layer 2 NPA address. In broadcast networks this
protection can be used to prevent an intruder tracking the protection can be used to prevent an intruder tracking the
identity of ULE Receivers and the volume of their traffic. identity of ULE Receivers and the volume of their traffic.
o Integrity protection and authentication of the ULE source is o Integrity protection and authentication of the ULE source is
required against active attacks described in section 3.2. required against active attacks described in section 3.2.
o Protection against replay attacks. This is required for the o Protection against replay attacks. This is required for the
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o Layer L2 ULE Source and Receiver authentication: This is o Layer L2 ULE Source and Receiver authentication: This is
normally performed during the initial key exchange and normally performed during the initial key exchange and
authentication phase, before the ULE Receiver can join a authentication phase, before the ULE Receiver can join a
secure session with the ULE Encapsulator (ULE source). This is secure session with the ULE Encapsulator (ULE source). This is
normally receiver to hub authentication and it could be either normally receiver to hub authentication and it could be either
unidirectional or bidirectional authentication based on the unidirectional or bidirectional authentication based on the
underlying key management protocol. underlying key management protocol.
Other general requirements are: Other general requirements are:
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o Decoupling of ULE key management functions from ULE security o Decoupling of ULE key management functions from ULE security
services such as encryption and source authentication. This services such as encryption and source authentication. This
allows the independent development of both systems. allows the independent development of both systems.
o Support for automated as well as manual insertion of keys and o Support for automated as well as manual insertion of keys and
policy into the relevant databases. policy into the relevant databases.
o Algorithm agility is needed. Changes in crypto algorithms, o Algorithm agility is needed. Changes in crypto algorithms,
hashes as they become obsolete should be updated without hashes as they become obsolete should be updated without
affecting the overall security of the system. affecting the overall security of the system.
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unicast, etc), it is often not appropriate to provide IP unicast, etc), it is often not appropriate to provide IP
confidentiality services for the entire ULE Stream. For many confidentiality services for the entire ULE Stream. For many
expected applications of ULE, a finer-grain control is expected applications of ULE, a finer-grain control is
therefore required, at least permitting control of data therefore required, at least permitting control of data
confidentiality/authorisation at the level of a single MAC/NPA confidentiality/authorisation at the level of a single MAC/NPA
address. address.
Examining the threat cases in section 3.3, the security Examining the threat cases in section 3.3, the security
requirements for each case can be summarised as: requirements for each case can be summarised as:
o Case 1: Data flow confidentiality MUST be provided to prevent o Case 1: Data confidentiality MUST be provided to prevent
monitoring of the ULE data (such as user information and IP monitoring of the ULE data (such as user information and IP
addresses). Protection of NPA addresses MAY be provided to addresses). Protection of NPA addresses MAY be provided to
prevent tracking ULE Receivers and their communications. prevent tracking ULE Receivers and their communications.
o Case 2: In addition to case 1 requirements, new measures need o Case 2: In addition to case 1 requirements, new measures need
to be implemented such as authentication schemes using Message to be implemented such as authentication schemes using Message
Authentication Codes, digital signatures or TESLA [RFC4082] in Authentication Codes, digital signatures or TESLA [RFC4082] in
order to provide integrity protection and source order to provide integrity protection and source
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authentication, and using sequence numbers to protect against authentication, and using sequence numbers to protect against
replay attacks. In terms of outsider attacks, group replay attacks. In terms of outsider attacks, group
authentication using Message Authentication Codes should authentication using Message Authentication Codes should
provide the same level of security. This will significantly provide the same level of security. This will significantly
reduce the ability of intruders to successfully inject their reduce the ability of intruders to successfully inject their
own data into the MPEG-TS stream. However, scenario 2 threats own data into the MPEG-TS stream. However, scenario 2 threats
apply only in specific service cases, and therefore apply only in specific service cases, and therefore
authentication and protection against replay attacks are authentication and protection against replay attacks are
OPTIONAL. Such measures incur additional transmission as well OPTIONAL. Such measures incur additional transmission as well
as processing overheads. Moreover, intrusion detection systems as processing overheads. Moreover, intrusion detection systems
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hosts. IPsec in transport mode can be used for end-to-end hosts. IPsec in transport mode can be used for end-to-end
security transparently over MPEG-2 transmission links with little security transparently over MPEG-2 transmission links with little
impact. impact.
In the context of MPEG-2 transmission links, if IPsec is used to In the context of MPEG-2 transmission links, if IPsec is used to
secure a ULE link, then the ULE Encapsulator and Receivers are secure a ULE link, then the ULE Encapsulator and Receivers are
equivalent to the security gateways in IPsec terminology. A equivalent to the security gateways in IPsec terminology. A
security gateway implementation of IPsec uses tunnel mode. Such security gateway implementation of IPsec uses tunnel mode. Such
usage has the following disadvantages: usage has the following disadvantages:
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o There is an extra transmission overhead associated with using o There is an extra transmission overhead associated with using
IPsec in tunnel mode, i.e. the extra IP header (IPv4 or IPv6). IPsec in tunnel mode, i.e. the extra IP header (IPv4 or IPv6).
o There is a need to protect the identity (NPA) of ULE Receivers o There is a need to protect the identity (NPA) of ULE Receivers
over the ULE broadcast medium; IPsec is not suitable for over the ULE broadcast medium; IPsec is not suitable for
providing this service. In addition, the interfaces of these providing this service. In addition, the interfaces of these
devices do not necessarily have IP addresses (they can be L2 devices do not necessarily have IP addresses (they can be L2
devices). devices).
o Multicast is considered a major service over ULE links. The o Multicast is considered a major service over ULE links. The
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o When a PID is shared between several users, each ULE Receiver o When a PID is shared between several users, each ULE Receiver
needs to decrypt all MPEG-2 TS Packets with a matching PID, needs to decrypt all MPEG-2 TS Packets with a matching PID,
possibly including those that are not required to be possibly including those that are not required to be
forwarded. Therefore it does not have the flexibility to forwarded. Therefore it does not have the flexibility to
separately secure individual IP flows. separately secure individual IP flows.
o When a PID is shared between several users, the ULE Receivers o When a PID is shared between several users, the ULE Receivers
will have access to private traffic destined to other ULE will have access to private traffic destined to other ULE
Receivers, since they share a common PID and key. Receivers, since they share a common PID and key.
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o IETF-based key management is not used in existing systems. o IETF-based key management is not used in existing systems.
Existing access control mechanisms have limited flexibility in Existing access control mechanisms have limited flexibility in
terms of controlling the use of key and rekeying. Therefore if terms of controlling the use of key and rekeying. Therefore if
the key is compromised, then this will impact several ULE the key is compromised, then this will impact several ULE
Receivers. Receivers.
Currently there are few deployed L2 security systems for MPEG-2 Currently there are few deployed L2 security systems for MPEG-2
transmission networks. Conditional access for digital TV transmission networks. Conditional access for digital TV
broadcasting is one example. However, this approach is optimised broadcasting is one example. However, this approach is optimised
for TV services and is not well-suited to IP packet transmission. for TV services and is not well-suited to IP packet transmission.
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This method does not preclude the use of IPsec at L3 (or TLS This method does not preclude the use of IPsec at L3 (or TLS
[RFC4346] at L4). IPsec and TLS provide strong authentication of [RFC4346] at L4). IPsec and TLS provide strong authentication of
the end-points in the communication. the end-points in the communication.
L3 end-to-end security would partially deny the advantage listed L3 end-to-end security would partially deny the advantage listed
just above (use of PEP, compression etc), since those techniques just above (use of PEP, compression etc), since those techniques
could only be applied to TCP packets bearing a TCP-encapsulated could only be applied to TCP packets bearing a TCP-encapsulated
IPsec packet exchange, but not the TCP packets of the original IPsec packet exchange, but not the TCP packets of the original
applications, which in particular inhibits compression. applications, which in particular inhibits compression.
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End-to-end security (IPsec, TLS, etc.) may be used independently End-to-end security (IPsec, TLS, etc.) may be used independently
to provide strong authentication of the end-points in the to provide strong authentication of the end-points in the
communication. This authentication is desirable in many scenarios communication. This authentication is desirable in many scenarios
to ensure that the correct information is being exchanged between to ensure that the correct information is being exchanged between
the trusted parties, whereas Layer 2 methods cannot provide this the trusted parties, whereas Layer 2 methods cannot provide this
guarantee. guarantee.
6. Design recommendations for ULE Security Header Extension 6. Design recommendations for ULE Security Header Extension
Table 1 below shows the threats that are applicable to ULE Table 1 below shows the threats that are applicable to ULE
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| of Messages | | | | | | | | of Messages | | | | | | |
--------------------------------------------------------------- ---------------------------------------------------------------
Table 1: Security techniques to mitigate network threats Table 1: Security techniques to mitigate network threats
in ULE Networks. in ULE Networks.
A modular design to ULE Security may allow it to use and benefit A modular design to ULE Security may allow it to use and benefit
from IETF key management protocols, such as GSAKMP [RFC4535] and from IETF key management protocols, such as GSAKMP [RFC4535] and
GDOI [RFC3547] protocols defined by the IETF Multicast Security GDOI [RFC3547] protocols defined by the IETF Multicast Security
(MSEC) working group. This does not preclude the use of other key (MSEC) working group. This does not preclude the use of other key
management methods in scenarios where this is more appropriate. management methods in scenarios where this is more appropriate.
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IPsec or TLS also provide a proven security architecture defining IPsec or TLS also provide a proven security architecture defining
key exchange mechanisms and the ability to use a range of key exchange mechanisms and the ability to use a range of
cryptographic algorithms. ULE security can make use of these cryptographic algorithms. ULE security can make use of these
established mechanisms and algorithms. established mechanisms and algorithms.
7. Compatibility with Generic Stream Encapsulation 7. Compatibility with Generic Stream Encapsulation
The [ID-EXT] document describes two new Header Extensions that The [ID-EXT] document describes two new Header Extensions that
may be used with Unidirectional Link Encapsulation, ULE, may be used with Unidirectional Link Encapsulation, ULE,
[RFC4326] and the Generic Stream Encapsulation (GSE) that has [RFC4326] and the Generic Stream Encapsulation (GSE) that has
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Receivers) is considered as an additional security mechanism to Receivers) is considered as an additional security mechanism to
IPsec, TLS, and application layer end-to-end security, and not as IPsec, TLS, and application layer end-to-end security, and not as
a replacement. It allows a network operator to provide similar a replacement. It allows a network operator to provide similar
functions to that of IPsec, but in addition provides MPEG-2 functions to that of IPsec, but in addition provides MPEG-2
transmission link confidentiality and protection of ULE Receiver transmission link confidentiality and protection of ULE Receiver
identity (NPA). End-to-end security mechanism may then be used identity (NPA). End-to-end security mechanism may then be used
additionally and independently for providing strong additionally and independently for providing strong
authentication of the end-points in the communication. authentication of the end-points in the communication.
Annexe 1 describes a set of building blocks that may be used to Annexe 1 describes a set of building blocks that may be used to
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realise a framework that provides ULE security functions. realise a framework that provides ULE security functions.
9. Security Considerations 9. Security Considerations
Link-layer (L2) encryption of IP traffic is commonly used in Link-layer (L2) encryption of IP traffic is commonly used in
broadcast/radio links to supplement End-to-End security (e.g. broadcast/radio links to supplement End-to-End security (e.g.
provided by TLS [RFC4346], SSH [RFC4251], IPsec [RFC4301). A provided by TLS [RFC4346], SSH [RFC4251], IPsec [RFC4301).
common objective is to provide the same level of privacy as wired
links. It is recommended that an ISP or user provide end-to-end A common objective is to provide the same level of privacy as
security services based on well known mechanisms such as IPsec or wired links. It is recommended that an ISP or user provide end-
TLS. to-end security services based on well known mechanisms such as
IPsec or TLS.
This document provides a threat analysis and derives the security This document provides a threat analysis and derives the security
requirements to provide link encryption and optional link-layer requirements to provide link encryption and optional link-layer
integrity / authentication of the SNDU payload. integrity / authentication of the SNDU payload.
There are some security issues that were raised in RFC 4326 There are some security issues that were raised in RFC 4326
[RFC4326] that are not addressed in this document (out of scope) [RFC4326] that are not addressed in this document (out of scope)
such as: such as:
o The security issue with un-initialised stuffing bytes. In o The security issue with un-initialised stuffing bytes. In
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This document does not define any protocol and does not require This document does not define any protocol and does not require
any IANA assignments but a subsequent document that defines a any IANA assignments but a subsequent document that defines a
layer 2 security extension to ULE will require IANA involvement. layer 2 security extension to ULE will require IANA involvement.
11. Acknowledgments 11. Acknowledgments
The authors acknowledge the help and advice from Gorry Fairhurst The authors acknowledge the help and advice from Gorry Fairhurst
(University of Aberdeen). The authors also acknowledge (University of Aberdeen). The authors also acknowledge
contributions from Laurence Duquerroy and Stephane Coombes (ESA), contributions from Laurence Duquerroy and Stephane Coombes (ESA),
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Yim Fun Hu (University of Bradford) and Michael Noisternig from Yim Fun Hu (University of Bradford) and Michael Noisternig from
University of Salzburg. University of Salzburg.
12. References 12. References
12.1. Normative References 12.1. Normative References
[ISO-MPEG2] "Information technology -- generic coding of moving [ISO-MPEG2] "Information technology -- generic coding of moving
pictures and associated audio information systems, pictures and associated audio information systems,
Part I", ISO 13818-1, International Standards Part I", ISO 13818-1, International Standards
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12.2. Informative References 12.2. Informative References
[ID-AR] G. Fairhurst, M-J Montpetit "Address Resolution [ID-AR] G. Fairhurst, M-J Montpetit "Address Resolution
Mechanisms for IP Datagrams over MPEG-2 Networks", Mechanisms for IP Datagrams over MPEG-2 Networks",
Work in Progress <draft-ietf-ipdvb-ar-05.txt. Work in Progress <draft-ietf-ipdvb-ar-05.txt.
[ID-EXT] G. Fairhurst and B. Collini-Nocker, "Extension [ID-EXT] G. Fairhurst and B. Collini-Nocker, "Extension
Formats for Unidirectional Lightweight Encapsulation Formats for Unidirectional Lightweight Encapsulation
(ULE) and the Generic Stream Encapsulation (GSE)", (ULE) and the Generic Stream Encapsulation (GSE)",
Work in Progress, draft-ietf-ipdvb-ule-ext-04.txt, Work in Progress, draft-ietf-ipdvb-ule-ext-06.txt,
August 2007. August 2007.
[IEEE-802] "Local and metropolitan area networks-Specific [IEEE-802] "Local and metropolitan area networks-Specific
requirements Part 2: Logical Link Control", IEEE requirements Part 2: Logical Link Control", IEEE
802.2, IEEE Computer Society, (also ISO/IEC 8802-2), 802.2, IEEE Computer Society, (also ISO/IEC 8802-2),
1998. 1998.
[ISO-8802] ISO/IEC 8802.2, "Logical Link Control", International [ISO-8802] ISO/IEC 8802.2, "Logical Link Control", International
Standards Organisation (ISO), 1998. Standards Organisation (ISO), 1998.
skipping to change at page 19, line 46 skipping to change at line 925
moving pictures and associated audio information moving pictures and associated audio information
Systems", International Telecommunication Union, Systems", International Telecommunication Union,
(ITU-T), 1995. (ITU-T), 1995.
[RFC4259] Montpetit, M.-J., Fairhurst, G., Clausen, H., [RFC4259] Montpetit, M.-J., Fairhurst, G., Clausen, H.,
Collini-Nocker, B., and H. Linder, "A Framework for Collini-Nocker, B., and H. Linder, "A Framework for
Transmission of IP Datagrams over MPEG-2 Networks", Transmission of IP Datagrams over MPEG-2 Networks",
IETF RFC 4259, November 2005. IETF RFC 4259, November 2005.
[RFC4326] Fairhurst, G. and B. Collini-Nocker, "Unidirectional [RFC4326] Fairhurst, G. and B. Collini-Nocker, "Unidirectional
Cruickshank et.al. Expires April 12, 2008 [Page
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Lightweight Encapsulation (ULE) for Transmission of Lightweight Encapsulation (ULE) for Transmission of
IP Datagrams over an MPEG-2 Transport Stream (TS)", IP Datagrams over an MPEG-2 Transport Stream (TS)",
IETF RFC 4326, December 2005. IETF RFC 4326, December 2005.
[ETSI-DAT] EN 301 192, "Digital Video Broadcasting (DVB); DVB [ETSI-DAT] EN 301 192, "Digital Video Broadcasting (DVB); DVB
Specifications for Data Broadcasting", European Specifications for Data Broadcasting", European
Telecommunications Standards Institute (ETSI). Telecommunications Standards Institute (ETSI).
[BELLOVIN] S.Bellovin, "Problem Area for the IP Security [BELLOVIN] S.Bellovin, "Problem Area for the IP Security
protocols", Computer Communications Review 2:19, pp. protocols", Computer Communications Review 2:19, pp.
skipping to change at page 20, line 44 skipping to change at line 974
[RFC3135] J. Border, M. Kojo, eyt. al., "Performance Enhancing [RFC3135] J. Border, M. Kojo, eyt. al., "Performance Enhancing
Proxies Intended to Mitigate Link-Related Proxies Intended to Mitigate Link-Related
Degradations", IETF RFC 3135, June 2001. Degradations", IETF RFC 3135, June 2001.
[RFC4301] Kent, S. and Seo K., "Security Architecture for the [RFC4301] Kent, S. and Seo K., "Security Architecture for the
Internet Protocol", IETF RFC 4301, December 2006. Internet Protocol", IETF RFC 4301, December 2006.
[RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D.,
Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J.,
and L. Wood, "Advice for Internet Subnetwork and L. Wood, "Advice for Internet Subnetwork
Cruickshank et.al. Expires April 12, 2008 [Page
20]
Designers", BCP 89, IETF RFC 3819, July 2004. Designers", BCP 89, IETF RFC 3819, July 2004.
[RFC4251] T. Ylonen, C. Lonvick, Ed., "The Secure Shell (SSH) [RFC4251] T. Ylonen, C. Lonvick, Ed., "The Secure Shell (SSH)
Protocol Architecture", IETF RFC 4251, January 2006. Protocol Architecture", IETF RFC 4251, January 2006.
13. Author's Addresses 13. Author's Addresses
Haitham Cruickshank,
Centre for Communications System Research (CCSR), Haitham Cruickshank
University of Surrey, Centre for Communications System Research (CCSR)
University of Surrey
Guildford, Surrey, GU2 7XH Guildford, Surrey, GU2 7XH
UK UK
Email: h.cruickshank@surrey.ac.uk Email: h.cruickshank@surrey.ac.uk
Sunil Iyengar, Sunil Iyengar
Centre for Communications System Research (CCSR), Centre for Communications System Research (CCSR)
University of Surrey, University of Surrey
Guildford, Surrey, GU2 7XH Guildford, Surrey, GU2 7XH
UK UK
Email: S.Iyengar@surrey.ac.uk Email: S.Iyengar@surrey.ac.uk
Prashant Pillai, Prashant Pillai
Mobile and Satellite Communications Research Centre (MSCRC), Mobile and Satellite Communications Research Centre (MSCRC)
School of Engineering, Design and Technology, School of Engineering, Design and Technology
University of Bradford, University of Bradford
Richmond Road, Bradford BD7 1DP Richmond Road, Bradford BD7 1DP
UK UK
Email: p.pillai@bradford.ac.uk Email: p.pillai@bradford.ac.uk
14. IPR Notices 14. IPR Notices
Copyright (c) The IETF Trust (2007). Copyright (c) The IETF Trust (2007).
14.1. Intellectual Property Statement 14.1. Intellectual Property Statement
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided Cruickshank et.al. Expires April 12, 2008 [Page
on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE 21]
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL This document and the information contained herein are provided on an
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
FITNESS FOR A PARTICULAR PURPOSE. OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
14.2. Intellectual Property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be Intellectual Property Rights or other rights that might be claimed to
claimed to pertain to the implementation or use of the technology pertain to the implementation or use of the technology described in
described in this document or the extent to which any license this document or the extent to which any license under such rights
under such rights might or might not be available; nor does it might or might not be available; nor does it represent that it has
represent that it has made any independent effort to identify any made any independent effort to identify any such rights. Information
such rights. Information on the procedures with respect to on the procedures with respect to rights in RFC documents can be
rights in RFC documents can be found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the attempt made to obtain a general license or permission for the use of
use of such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR specification can be obtained from the IETF on-line IPR repository at
repository at http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention
any copyrights, patents or patent applications, or other
proprietary rights that may cover technology that may be required
to implement this standard. Please address the information to
the IETF at ietf-ipr@ietf.org.
15. Copyright Statement
Copyright (C) The IETF Trust (2007). The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Appendix A: ULE Security Framework Appendix A: ULE Security Framework
This section defines a security framework for the deployment of This section defines a security framework for the deployment of
secure ULE networks. secure ULE networks.
A.1 Building Blocks A.1 Building Blocks
This ULE Security framework defines the following building blocks This ULE Security framework defines the following building blocks
Cruickshank et.al. Expires April 12, 2008 [Page
22]
as shown in figure 2 below: as shown in figure 2 below:
o The Key Management Block o The Key Management Block
o The ULE Security Extension Header Block o The ULE Security Extension Header Block
o The ULE Databases Block o The ULE Databases Block
Within the Key Management block the communication between the Within the Key Management block the communication between the
Group Member entity and the Group Server entity happens in the Group Member entity and the Group Server entity happens in the
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| | / \ | | / \
| | | | | |
| | | | | |
+------+-+--------+ ULE Data +------+-+--------+ ULE Data
| ULE Security | Plane | ULE Security | Plane
| Extension Header| | | Extension Header| |
| Block | | | Block | |
+-----------------+ \ / +-----------------+ \ /
----- -----
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Figure 2: Secure ULE Framework Building Blocks Figure 2: Secure ULE Framework Building Blocks
A.1.1 Key Management Block A.1.1 Key Management Block
A key management framework is required to provide security at the A key management framework is required to provide security at the
ULE level using extension headers. This key management framework ULE level using extension headers. This key management framework
is responsible for user authentication, access control, and is responsible for user authentication, access control, and
Security Association negotiation (which include the negotiations Security Association negotiation (which include the negotiations
of the security algorithms to be used and the generation of the of the security algorithms to be used and the generation of the
different session keys as well as policy material). The Key different session keys as well as policy material). The Key
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A.1.2 ULE Extension Header Block A.1.2 ULE Extension Header Block
A new security extension header for the ULE protocol is required A new security extension header for the ULE protocol is required
to provide the security features of data confidentiality, data to provide the security features of data confidentiality, data
integrity, data authentication and mechanisms to prevent replay integrity, data authentication and mechanisms to prevent replay
attacks. Security keying material will be used for the different attacks. Security keying material will be used for the different
security algorithms (for encryption/decryption, MAC generation, security algorithms (for encryption/decryption, MAC generation,
etc.), which are used to meet the security requirements, etc.), which are used to meet the security requirements,
described in detail in Section 4 of this document. described in detail in Section 4 of this document.
This block will use the keying material and policy information This block will use the keying material and policy information from
from the ULE security database block on the ULE payload to the ULE security database block on the ULE payload to generate the
generate the secure ULE Extension Header or to decipher the secure ULE Extension Header or to decipher the secure ULE extension
secure ULE extension header to get the ULE payload. An example header to get the ULE payload. An example overview of the ULE
overview of the ULE Security extension header format along with Security extension header format along with the ULE header and
the ULE header and payload is shown in figure 3 below. There payload is shown in figure 3 below. There could be other extension
could be other extension headers (either mandatory or optional) headers (either mandatory or optional). It is RECOMMENDED that these
but these will always be placed after the security extension are placed after the security extension header. This permits full
header. However, there is an exception: the timestamp extension protection for all headers. It avoids situations where the SNDU has
may be placed before the security extension header [ID-EXT]. When to be discarded on processing the security extension header, while
applying the security services for example confidentiality, input preceding headers have already have been evaluated. One exception is
to the cipher algorithm will cover the fields from the end of the the Timestamp extension which SHOULD precede the security extension
security extension header to the end of the PDU.
Cruickshank et.al. Expires April 12, 2008 [Page
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header [ID-EXT].. When applying the security services for example
confidentiality, input to the cipher algorithm will cover the fields
from the end of the security extension header to the end of the PDU.
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+-------+------+-------------------------------+------+ +-------+------+-------------------------------+------+
| ULE |SEC | Protocol Data Unit | | | ULE |SEC | Protocol Data Unit | |
|Header |Header| |CRC-32| |Header |Header| |CRC-32|
+-------+------+-------------------------------+------+ +-------+------+-------------------------------+------+
Figure 3: ULE Security Header Extension Placement Figure 3: ULE Security Header Extension Placement
A.1.3 ULE Security Databases Block A.1.3 ULE Security Databases Block
There needs to be two databases i.e. similar to the IPSec There needs to be two databases i.e. similar to the IPSec
databases. databases.
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While the first interface is used by the Key Management Block to While the first interface is used by the Key Management Block to
insert keys, security associations and policies into the ULE insert keys, security associations and policies into the ULE
Database Block, the second interface is used by the ULE Security Database Block, the second interface is used by the ULE Security
Extension Header Block to get the keys and policy material for Extension Header Block to get the keys and policy material for
generation of the security extension header. generation of the security extension header.
A.2.1 Key Management <-> ULE Security databases A.2.1 Key Management <-> ULE Security databases
This interface is between the Key Management group member block This interface is between the Key Management group member block
Cruickshank et.al. Expires April 12, 2008 [Page
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(GM client) and the ULE Security Database block (shown in figure (GM client) and the ULE Security Database block (shown in figure
2). The Key Management GM entity will communicate with the GCKS 2). The Key Management GM entity will communicate with the GCKS
and then get the relevant security information (keys, cipher and then get the relevant security information (keys, cipher
mode, security service, ULE_Security_ID and other relevant keying mode, security service, ULE_Security_ID and other relevant keying
material as well as policy) and insert this data into the ULE material as well as policy) and insert this data into the ULE
Security database block. The Key Management could be either Security database block. The Key Management could be either
automated (e.g. GSAKMP [RFC4535] or GDOI [RFC3547]) or manually automated (e.g. GSAKMP [RFC4535] or GDOI [RFC3547]) or manually
inserted using this interface. The following three interface inserted using this interface. The following three interface
functions are defined: functions are defined:
skipping to change at page 26, line 35 skipping to change at line 1262
the ULE SNDU will first get the record from the Security Database the ULE SNDU will first get the record from the Security Database
using the ULE_Security_ID, the Destination Address and possibly using the ULE_Security_ID, the Destination Address and possibly
the PID. It then uses this information to decrypt the ULE the PID. It then uses this information to decrypt the ULE
extension header. For both cases (either send or receive traffic) extension header. For both cases (either send or receive traffic)
only one interface is needed since the only difference between only one interface is needed since the only difference between
the sender and receiver is the direction of the flow of traffic: the sender and receiver is the direction of the flow of traffic:
. Get_record_database (char * Database, char * record, char * . Get_record_database (char * Database, char * record, char *
Unique_ID); Unique_ID);
Cruickshank et.al. Expires April 12, 2008 [Page
27]
>>> NOTE to RFC Editor: Please remove this appendix prior to >>> NOTE to RFC Editor: Please remove this appendix prior to
publication] publication]
Document History Document History
Working Group Draft 00 Working Group Draft 00
o Fixed editorial mistakes and ID style for WG adoption. o Fixed editorial mistakes and ID style for WG adoption.
Working Group Draft 01 Working Group Draft 01
skipping to change at page 27, line 35 skipping to change at line 1307
o Fixed editorial mistakes and added some important changes as o Fixed editorial mistakes and added some important changes as
pointed out by Gorry Fairhurst. pointed out by Gorry Fairhurst.
o Table 1 added in Section 6.2 to list the different security o Table 1 added in Section 6.2 to list the different security
techniques to mitigate the various possible network threats. techniques to mitigate the various possible network threats.
o Figure 2 modified to clearly explain the different interfaces o Figure 2 modified to clearly explain the different interfaces
present in the framework. present in the framework.
Cruickshank et.al. Expires April 12, 2008 [Page
28]
o New Section 7 has been added. o New Section 7 has been added.
o New Section 6 has been added. o New Section 6 has been added.
o The previous sections 5 and 6 have been combined to section 5. o The previous sections 5 and 6 have been combined to section 5.
o Sections 3, 8 and 9 have been rearranged and updated with o Sections 3, 8 and 9 have been rearranged and updated with
comments and suggestions from Michael Noisternig from comments and suggestions from Michael Noisternig from
University of Salzburg. University of Salzburg.
skipping to change at line 1257 skipping to change at line 1332
Working Group Draft 04 Working Group Draft 04
o Fixed editorial mistakes and added some important changes as o Fixed editorial mistakes and added some important changes as
pointed out by DVB-GBS group, Gorry Fairhurst and Laurence pointed out by DVB-GBS group, Gorry Fairhurst and Laurence
Duquerroy. Duquerroy.
o Table 1 modified to have consistent use of Security Services. o Table 1 modified to have consistent use of Security Services.
o Text modified to be consistent with the draft-ietf-ipdvb-ule- o Text modified to be consistent with the draft-ietf-ipdvb-ule-
ext-04.txt ext-04.txt
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