Asymmetric Manifest Based Integrity
draft-ietf-mboned-ambi-03
| Document | Type | Active Internet-Draft (mboned WG) | |
|---|---|---|---|
| Authors | Jake Holland , Kyle Rose | ||
| Last updated | 2022-03-07 | ||
| Replaces | draft-jholland-mboned-ambi | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
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| Additional resources |
Yang catalog entry for ietf-ambi@2019-08-25.yang
Yang impact analysis for draft-ietf-mboned-ambi Mailing list discussion |
||
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| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
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draft-ietf-mboned-ambi-03
Mboned J. Holland
Internet-Draft K. Rose
Intended status: Standards Track Akamai Technologies, Inc.
Expires: 8 September 2022 7 March 2022
Asymmetric Manifest Based Integrity
draft-ietf-mboned-ambi-03
Abstract
This document defines Asymmetric Manifest-Based Integrity (AMBI).
AMBI allows each receiver or forwarder of a stream of multicast
packets to check the integrity of the contents of each packet in the
data stream. AMBI operates by passing cryptographically verifiable
hashes of the data packets inside manifest messages, and sending the
manifests over authenticated out-of-band communication channels.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 8 September 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Comparison with TESLA . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Notes for Contributors and Reviewers . . . . . . . . . . 4
1.3.1. Venues for Contribution and Discussion . . . . . . . 5
1.3.2. Non-obvious doc choices . . . . . . . . . . . . . . . 5
2. Threat Model . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Security Anchors . . . . . . . . . . . . . . . . . . . . 6
2.1.1. Alternatives and Their Requirements . . . . . . . . . 7
2.2. System Security . . . . . . . . . . . . . . . . . . . . . 8
3. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 8
3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2. Buffering of Packets and Digests . . . . . . . . . . . . 9
3.2.1. Validation Windows . . . . . . . . . . . . . . . . . 10
3.2.2. Preserving Inter-packet Gap . . . . . . . . . . . . . 11
3.3. Packet Digests . . . . . . . . . . . . . . . . . . . . . 11
3.3.1. Digest Profile . . . . . . . . . . . . . . . . . . . 11
3.3.2. Pseudoheader . . . . . . . . . . . . . . . . . . . . 13
3.4. Manifests . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4.1. Manifest Layout . . . . . . . . . . . . . . . . . . . 14
3.5. Transitioning to Other Manifest Streams . . . . . . . . . 18
4. Transport Considerations . . . . . . . . . . . . . . . . . . 18
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2. HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3. TLS . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.4. DTLS . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 20
6.2. Module . . . . . . . . . . . . . . . . . . . . . . . . . 20
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
7.1. The YANG Module Names Registry . . . . . . . . . . . . . 24
7.2. The XML Registry . . . . . . . . . . . . . . . . . . . . 24
7.3. Media Type . . . . . . . . . . . . . . . . . . . . . . . 24
7.4. URI Schemes . . . . . . . . . . . . . . . . . . . . . . . 25
7.4.1. TLS . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.4.2. DTLS . . . . . . . . . . . . . . . . . . . . . . . . 25
8. Security Considerations . . . . . . . . . . . . . . . . . . . 25
8.1. Predictable Packets . . . . . . . . . . . . . . . . . . . 25
8.2. Attacks on Side Applications . . . . . . . . . . . . . . 25
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
10.1. Normative References . . . . . . . . . . . . . . . . . . 26
10.2. Informative References . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
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1. Introduction
Multicast transport poses security problems that are not easily
addressed by the same security mechanisms used for unicast transport.
The "Introduction" sections of the documents describing TESLA
[RFC4082], and TESLA in SRTP [RFC4383], and TESLA with ALC and NORM
[RFC5776] present excellent overviews of the challenges unique to
multicast authentication for use cases like wide scale software or
video distribution with a high data transfer rate. The challenges
are briefly summarized here:
* A MAC based on a symmetric shared secret cannot be used because
each packet has multiple receivers that do not trust each other,
and using a symmetric shared secret exposes the same secret to
each receiver.
* Asymmetric per-packet signatures can handle only very low bit-
rates because of the transport and computational overhead
associated with signature transmission and verification.
* An asymmetric signature of a larger message comprising multiple
packets requires reliable receipt of all such packets, something
that cannot be guaranteed in a timely manner even for protocols
that do provide reliable delivery, and the retransmission of which
may anyway exceed the useful lifetime for data formats that can
otherwise tolerate some degree of loss.
Aymmetric Manifest-Based Integrity (AMBI) defines a method for
receivers or middle boxes to cryptographically authenticate and
verify the integrity of a stream of packets by comparing the data
packets to a stream of packet "manifests" (described in Section 3.4)
received via an out-of-band communication channel that provides
authentication and verifiable integrity.
Each manifest contains a message digest (described in Section 3.3)
for each packet in a sequence of packets from the data stream,
hereafter called a "packet digest". The packet digest incorporates a
cryptographic hash of the packet contents and some identifying data
from the packet, according to a defined digest profile for the data
stream.
Upon receipt of a packet digest inside a manifest conveyed in a
secure channel and verification that the packet digest of a received
data packet matches, the receiver has proof of the integrity of the
contents of the data packet corresponding to that digest.
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This document defines the "ietf-ambi" YANG [RFC7950] model in
Section 6 as an extension of the "ietf-dorms" model defined in
[I-D.draft-ietf-mboned-dorms]. Also defined are new URI schemes for
transport of manifests over TLS or DTLS, and a new media type for
transport of manifests over HTTPS. The encodings for these are
defined in Section 4.
1.1. Comparison with TESLA
AMBI and TESLA [RFC4082] and [RFC5776] attempt to achieve a similar
goal of authenticating the integrity of streams of multicast packets.
AMBI imposes a higher overhead than TESLA imposes, as measured in the
amount of extra data required. In exchange, AMBI relaxes the
requirement for establishing an upper bound on clock synchronization
between sender and receiver, and allows for the use case of
authenticating multicast traffic before forwarding it through the
network, while also allowing receivers to authenticate the same
traffic. By contrast, this is not possible with TESLA because the
data packets can't be authenticated until a key is disclosed, so
either the middlebox has to forward data packets without first
authenticating them so that the receiver has them prior to key
disclosure, or the middlebox has to hold packets until the key is
disclosed, at which point the receiver can no longer establish their
authenticity.
The other new capability is that because AMBI provides authentication
information out of band, authentication can be retrofitted into some
pre-existing deployments without changing the protocol of the data
packets under some restrictions outlined in Section 8. By contrast,
TESLA requires a MAC to be added to each authenticated message.
1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119] and [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.3. Notes for Contributors and Reviewers
Note to RFC Editor: Please remove this section and its subsections
before publication.
This section is to provide references to make it easier to review the
development and discussion on the draft so far.
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1.3.1. Venues for Contribution and Discussion
This document is in the Github repository at:
https://github.com/GrumpyOldTroll/ietf-dorms-cluster
(https://github.com/GrumpyOldTroll/ietf-dorms-cluster)
Readers are welcome to open issues and send pull requests for this
document.
Please note that contributions may be merged and substantially
edited, and as a reminder, please carefully consider the Note Well
before contributing: https://datatracker.ietf.org/submit/note-well/
(https://datatracker.ietf.org/submit/note-well/)
Substantial discussion of this document should take place on the
MBONED working group mailing list (mboned@ietf.org).
* Join: https://www.ietf.org/mailman/listinfo/mboned
(https://www.ietf.org/mailman/listinfo/mboned)
* Search: https://mailarchive.ietf.org/arch/browse/mboned/
(https://mailarchive.ietf.org/arch/browse/mboned/)
1.3.2. Non-obvious doc choices
* TBD: we need a way to assert that we provide the full set of
packets for an (S,G) on all UDP ports and non-UDP protocols.
Naively authenticating UDP for specified ports and ignoring other
ports means that an attacker could attack a separate UDP port by
injecting traffic directed at it, potentially hitting a different
application that listens on 0.0.0.0, so an (S,G) with legitimately
authenticated UDP traffic on one port could be used to transport
UDP-based attacks to apps on another port or protocol unless they
are firewalled. Passing traffic for an (S,G) subscription would
open a new channel to such targets that otherwise would not be
reachable from the internet for users behind e.g. a CPE with nat
or connection-state-based firewalling.
* Dropped intent to support DTLS+FECFRAME in this spec because RFC
6363 seems incomprehensible on a few points, most notably demux
strategy between repair and source ADUs, which as written seems to
require specifying another layer. So support for this will have
to be a later separate RFC. However, for future extensibility
made manifest-stream into a list instead of a leaf-list so that it
can be an augment target for a later YANG extension with FEC
selection from the likewise-very-confusing semi-overlapping
registries at https://www.iana.org/assignments/rmt-fec-parameters/
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rmt-fec-parameters.xhtml (https://www.iana.org/assignments/rmt-
fec-parameters/rmt-fec-parameters.xhtml) defined by RFCs 5052 and
6363. See also RFC 6363, RFC 6681, and RFC 6865
2. Threat Model
AMBI is designed to operate over the internet, under the Internet
Threat Model described in [RFC3552].
AMBI aims to provide Data Integrity for a multicast data stream,
building on the security anchors described in Section 2.1 to do so.
The aim is to enable receivers to subscribe to and receive multicast
packets from a trusted sender without damage to the Systems Security
(Section 2.3 of [RFC3552]) for those receivers or other entities.
Thus, we assume there might be attackers on-path or off-path with the
capability to inject or modify packets, but that the attackers have
not compromised the sender or discovered any of the sender's secret
keys. We assume that an attacker may have compromised some receivers
of the multicast traffic, but still aim to provide the above security
properties for receivers that have not been compromised.
Those sending multicast traffic to receivers that include untrusted
receivers should avoid transmitting sensitive information that
requires strong confidentiality guarantees, due to the risk of
compromise from those receivers. Since multicast transmits the same
packets to potentially many receivers, in the presence of potentially
compromised receivers confidentiality of the content cannot be
assured.
However, any protocol that provides encryption of the packet data
before generating the packet digest can provide confidentiality
against on-path passive observers who do not possess the decryption
key. This level of confidentiality can be provided by any such
protocols without impact on AMBI's operation.
2.1. Security Anchors
Establishing the desired security properties for the multicast data
packets relies on secure delivery of some other information:
* Secured unicast connections (providing Data Integrity) to one or
more trusted DORMS [I-D.draft-ietf-mboned-dorms] servers that use
the AMBI extensions to the DORMS YANG model as defined in
Section 6
* Secure delivery (providing Data Integrity) of a stream of
manifests (Section 3.4)
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The secured unicast connection to the DORMS server provides the Peer
Entity authentication of the DORMS server that's needed to establish
the Data Integrity of the data it sends.
Note that DORMS provides a method for using DNS to bootstrap
discovery of the DORMS server. In contexts where secure DNS lookup
cannot be provided, it's still possible to establish a secure
connection to a trusted DORMS server as long as the trusted DORMS
server's hostname is known to the receivers (removing the need to use
DNS for that discovery). Once the server name is known, the ordinary
certificate verification of that hostname while establishing a secure
https connection provides the needed security properties to anchor
the rest.
Receiving unauthenticated data packets and knowing how to generate
packet digests from the manifest profile provided by the AMBI
extensions in the DORMS metadata allows the receiver to generate
packet digests based on the contents of the received packet, which
can be compared against the packet digests that were securely
received.
Comparing the digests and finding the same answer then provides Data
Integrity for the data packets that relies on one more property of
the digest generation algorithm:
* the difficulty of generating a collision for the packet digests
contained in the manifest.
Taken together, successful validation of the multicast data packets
proves within the above constraints that someone with control of the
manifest URI streams provided by the DORMS server has verified the
sending of the packets corresponding to the digests sent in that
stream of manifests.
2.1.1. Alternatives and Their Requirements
Other protocols that can provide authentication could also be used
for manifest delivery if defined later in another specification. For
example a protocol that asymmetrically signs each packet, as the one
defined in Section 3 of [RFC6584] does, would be a viable candidate
for a delivery protocol for manifests that could be delivered over a
multicast transport, which could have some important scalability
benefits.
Other methods of securely transmitting metadata equivalent to the
metadata provided by the "ietf-ambi" YANG model could also be used to
provide the same security guarantees with the manifest channels.
Defining other such possibilities is out of scope for this document.
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2.2. System Security
By providing the means to authenticate multicast packets, AMBI aims
to avoid giving attackers who can inject or modify packets the
ability to attack application vulnerabilities that might be possible
to exercise if those applications process the attack traffic. Many
of the entries in the Common Vulnerabilities and Exposures (CVE) list
at [CVE] (an extensive industry-wide database of software
vulnerabilities) have documented a variety of system security
problems that can result from maliciously generated UDP packets.
TBD: Fold in a mention of how off-path attacks are possible from most
places on the internet for interdomain multicast over AMT at an
ingest point, and how the multicast fanout downstream of that can
make it a good target if multicast sees more use. A diagram plus a
cleaned-up version of the on-list explanation here is probably
appropriate: https://mailarchive.ietf.org/arch/msg/mboned/
CG9FLjPwuno3MtvYvgNcD5p69I4/
(https://mailarchive.ietf.org/arch/msg/mboned/
CG9FLjPwuno3MtvYvgNcD5p69I4/). Nightmare scenario is zero-day RCE by
off-path attacker that takes over a significant number of the devices
watching a major sports event.
See also work-in-progress: https://squarooticus.github.io/draft-
krose-multicast-security/draft-krose-multicast-security.html
(https://squarooticus.github.io/draft-krose-multicast-security/draft-
krose-multicast-security.html)
3. Protocol Operation
3.1. Overview
In order to authenticate a data packet, AMBI receivers need to hold
these three pieces of information at the same time:
* the data packet
* an authenticated manifest containing the packet digest for the
data packet
* a digest profile defining the transformation from the data packet
to its packet digest
The manifests are delivered as a stream of manifests over an
authenticated data channel. Manifest contents MUST be authenticated
before they can be used to authenticate data packets.
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The manifest stream is composed of an ordered sequence of manifests
that each contain an ordered sequence of packet digests,
corresponding to the original packets as sent from their origin, in
the same order.
Note that a manifest contains potentially many packet digests, and
its size can be tuned to fit within a convenient PDU (Protocol Data
Unit) of the manifest transport stream. By doing so, many packet
digests for the multicast data stream can be delivered per packet of
the manifest transport. The intent is that even with unicast-based
manifest transport, multicast-style efficiencies of scale can still
be realized with only a relatively small unicast overhead, when
manifests use a unicast transport.
3.2. Buffering of Packets and Digests
Using different communication channels for the manifest stream and
the data stream introduces a possibility of desynchronization in the
timing of the received data between the different channels, so
receivers hold data packets and packet digests from the manifest
stream in buffers for some duration while awaiting the arrival of
their counterparts.
While holding a data packet, if the corresponding packet digest for
that packet arrives in the secured manifest stream, the data packet
is authenticated.
While holding an authenticated packet digest, if the corresponding
data packet arrives with a matching packet digest, the data packet is
authenticated.
Authenticating a data packet consumes one packet digest and prevents
re-learning a digest for the same sequence number with a hold-down
time equal to the hold time for packet digests. The hold-down is
necessary because a different manifest can send a duplicate packet
digest for the same packet sequence number, either when repeating of
packet digests is used for resilience to loss or when rotating
authentication keys, so re-learning the packet digest could allow a
replay of a data packet. After authenticating a packet, the digest
and any future digests for the same data packet remain consumed if it
has been used to authenticate a data packet, ignoring repeated
digests for the same sequence number until after the holddown timer
expires.
Once the data packet is authenticated it can be further processed by
the receiving application or forwarded through the receiving network.
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If the receiver's hold duration for a data packet expires without
authenticating the packet, the packet SHOULD be dropped as
unauthenticated. If the hold duration of a manifest expires, packet
digests last received in that manifest MUST be discarded.
When multiple digests for the same packet sequence number are
received, the latest received time for an authenticated packet digest
should be used for the expiration time.
3.2.1. Validation Windows
Since packet digests are usually smaller than the data packets, it's
RECOMMENDED that senders generate and send manifests with timing such
that the packet digests in a manifest will typically be received by
subscribed receivers before the data packets corresponding to those
digests are received.
This strategy reduces the buffering requirements at receivers, at the
cost of introducing some buffering of data packets at the sender,
since data packets are generated before their packet digests can be
added to manifests.
The RECOMMENDED default hold times at receivers are:
* 2 seconds for data packets
* 10 seconds for packet digests
The sender MAY recommend different values for specific data streams,
in order to tune different data streams for different performance
goals. The YANG model in Section 6 provides a mechanism for senders
to communicate the sender's recommendation for buffering durations.
These parameters are "data-hold-time" and "digest-hold-time",
expressed in milliseconds.
Receivers MAY deviate from the values recommended by the sender for a
variety of reasons, including their own memory constraints or local
administrative configuration (for example, it might improve user
experience in some situations to hold packets longer than the server
recommended when there are receiver-specific delays in the manifest
stream that exceed the server's expectations). Decreasing the
buffering durations recommended by the server increases the risk of
losing packets, but can be an appropriate tradeoff for specific
network conditions and hardware or memory constraints on some
devices.
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Receivers SHOULD follow the recommendations for hold times provided
by the sender (including the default values from the YANG model when
unspecified), subject to their capabilities and any administratively
configured overrides at the receiver.
3.2.2. Preserving Inter-packet Gap
It's RECOMMENDED that middle boxes forwarding buffered data packets
preserve the inter-packet gap between packets in the same data
stream, and that receiving libraries that perform AMBI-based
authentication provide mechanisms to expose the network arrival times
of packets to applications.
The purpose for this recommendation is to preserve the capability of
receivers to use techniques for available bandwidth detection or
network congestion based on observation of packet times and packet
dispersal, making use of known patterns in the sending. Examples of
such techniques include those described in [PathChirp], [PathRate],
and [WEBRC].
Note that this recommendation SHOULD NOT prevent the transmission of
an authenticated packet because the prior packet is unauthenticated.
This recommendation only asks implementations to delay the
transmission of an authenticated packet to correspond to the
interpacket gap if an authenticated packet was previously transmitted
and the authentication of the subsequent packet would otherwise burst
the packets more quickly.
This does not prevent the transmission of packets out of order
according to their order of authentication, only the timing of
packets that are transmitted, after authentication, in the same order
they were received.
For receiver applications, the time that the original packet was
received from the network SHOULD be made available to the receiving
application.
3.3. Packet Digests
3.3.1. Digest Profile
A packet digest is a message digest for a data packet, built
according to a digest profile defined by the sender.
The digest profile is defined by the sender, and specifies:
1. A cryptographically secure hash algorithm (REQUIRED)
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2. A manifest stream identifier
3. Whether to hash the IP payload or the UDP payload. (see
Section 3.3.1.1)
The hash algorithm is applied to a pseudoheader followed by the
packet payload, as determined by the digest profile. The computed
hash value is the packet digest.
TBD: As recommended by https://tools.ietf.org/html/rfc7696#section-
2.2 (https://tools.ietf.org/html/rfc7696#section-2.2), a companion
document containing the mandatory-to-implement cipher suite should
also be published separately and referenced by this document.
3.3.1.1. Payload Type
3.3.1.1.1. UDP vs. IP payload validation
When the manifest definition is at the UDP layer, it applies only to
packets with IP protocol of UDP (0x11) and the payload used for
calculating the packet digest includes only the UDP payload with
length as the number of UDP payload octets, as calculated by
subtracting the size of the UDP header from the UDP payload length.
When the manifest definition is at the IP layer, the payload used for
calculating the packet digest includes the full IP payload of the
data packets in the (S,G). There is no restriction on the IP
protocols that can be authenticated. The length field in the
pseudoheader is calculated by subtracting the IP Header Length from
the IP length, and is equal to the number of octets in the payload
for the digest calculation.
3.3.1.1.2. Motivation
Full IP payloads often aren't available to receivers without extra
privileges on end user operating systems, so it's useful to provide a
way to authenticate only the UDP payload, which is often the only
portion of the packet available to many receiving applications.
However, for some use cases a full IP payload is appropriate. For
example, when retrofitting some existing protocols, some packets may
be predictable or frequently repeated. Use of an IPSec
Authentication Header [RFC4302] is one way to disambiguate such
packets. Even though the shared secret means the Authentication
Header can't itself be used to authenticate the packet contents, the
sequence number in the Authentication Header can ensure that specific
packets are not repeated at the IP layer, and so it's useful for AMBI
to have the capability to authenticate such packets.
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Another example: some services might need to authenticate the UDP
options [I-D.ietf-tsvwg-udp-options]. When using the UDP payload,
the UDP options would not be part of the authenticated payload, but
would be included when using the IP payload type.
Lastly, since (S,G) subscription operates at the IP layer, it's
possible that some non-UDP protocols will need to be authenticated,
and the IP layer allows for this. However, most user-space transport
applications are expected to use the UDP layer authentication.
3.3.2. Pseudoheader
When calculating the hash for the packet digest, the hash algorithm
is applied to a pseudoheader followed by the payload from the packet.
The complete sequence of octets used to calculate the hash is
structured as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address (32 bits IPv4/128 bits IPv6) |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Address (32 bits IPv4/128 bits IPv6) |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Zeroes | Protocol | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Destination Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Manifest Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Data |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.3.2.1. Source Address
The IPv4 or IPv6 source address of the packet.
3.3.2.2. Destination Address
The IPv4 or IPv6 destination address of the packet.
3.3.2.3. Zeroes
All bits set to 0.
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3.3.2.4. Protocol
The IP Protocol field from IPv4, or the Next Header field for IPv6.
When using UDP-layer authentication, this value is always UDP (0x11)
but for IP-layer authentication it can vary per-packet.
3.3.2.5. Length
The length in octets of the Payload Data field, expressed as an
unsigned 16-bit integer.
3.3.2.6. Source Port
The source port of the packet. Zeroes if using IP-layer
authentication for a non-UDP protocol.
3.3.2.7. Destination Port
The UDP destination port of the packet. Zeroes if using IP-layer
authentication for a non-UDP protocol.
3.3.2.8. Manifest Identifier
The 32-bit identifier for the manifest stream.
3.3.2.9. Payload Data
The payload data includes either the IP payload or the UDP payload,
as indicated by the digest profile.
3.4. Manifests
3.4.1. Manifest Layout
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Manifest Stream Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Manifest sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| First packet sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T| Packet Digest Count | TLV Space (present iff T set) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... TLVs (Length=TLV Space or 0 if T unset) ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... Packet Digests ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.4.1.1. Manifest Stream Identifier
A 32-bit unsigned integer chosen by the sender. This value MUST be
equal to the "id" field in the manifest-stream in the "ietf-ambi"
model. If a manifest is seen that does not have the expected value
from the metadata provided for the manifest, the receiver MUST stop
processing this manifest and disconnect from this manifest stream.
It MAY reconnect with an exponential backoff starting at 1s, or it
MAY connect to an alternative manifest stream if one is known.
3.4.1.2. Manifest Sequence Number
A monotonically increasing 32-bit unsigned integer. Each manifest
sent by the sender increases this value by 1. On overflow it wraps
to 0.
It's RECOMMENDED to expire the manifest stream and start a new stream
for the data packets before a sequence number wrap is necessary.
3.4.1.3. First Packet Sequence Number
A monotonically increasing 32-bit unsigned integer. Each packet in
the data stream increases this value by 1.
It's RECOMMENDED to expire the manifest stream and start a new stream
for the data packets before a sequence number wrap is necessary.
Note: for redundancy, especially if using a manifest stream with
unreliable transport, successive manifests MAY provide duplicates of
the same packet digest with the same packet sequence number, using
overapping sets of packet sequence numbers. When received, these
reset the hold timer for the listed packet digests.
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3.4.1.4. T bit (TLVs Present)
If 1, this indicates the TLV Length and TLV space fields are present.
If 0, this indicates neither field is present.
3.4.1.5. Packet Digest Count
A 15-bit unsigned integer equal to the count of packet digests in the
manifest.
3.4.1.6. TLV Space
A 16-bit unsigned integer with the length of the TLVs section.
3.4.1.7. TLVs
These are Type-Length-Value blocks, back to back. These may be
extended by future specifications.
These are composed of 3 fields:
* Type: an 8-bit unsigned integer indicating the type. Type values
in 0-127 have an 8-bit length, and type values in 128-255 have a
16-bit length.
* Length: a 8-bit or 16-bit unsigned integer indicating the length
of the value
* Value: a value with semantics defined by the Type field.
Defined values:
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+======+==========+==============================================+
| Type | Name | Value |
+======+==========+==============================================+
| 0 | Pad | Length can be 0-255. Value is filled with 0 |
| | | and ignored by receiver. |
+------+----------+----------------------------------------------+
| 128 | Refresh | Length MUST be 2. Value is a 16-bit |
| | Deadline | unsigned integer number of seconds. When |
| | | this field is absent or zero, it means the |
| | | current digest profile for the current |
| | | manifest stream is stable. A nonzero value |
| | | means the authentication is transitioning to |
| | | a new manifest stream, and the set of digest |
| | | profiles SHOULD be refreshed by receivers |
| | | before this much time has elapsed in order |
| | | to avoid a disruption. See Section 3.5. |
+------+----------+----------------------------------------------+
Table 1
1-120 and 129-248 are unassigned 121-127 and 249-255 are reserved for
experiments
Any unknown values MUST be skipped and ignored by the receiver, using
the Length field to skip.
The total size of the manifest in octets is exactly equal to:
Size of digests * packet count + 14 if T is 0 Size of digests *
packet count + 16 + TLV Length if T is 1
The total size of the TLV space is exactly equal to:
(2 + Length) summed for each TLV
The total size of the TLV space MUST exactly equal TLV Length. If
the TLV space exceeds the TLV Length, the receiver MUST disconnect,
and behave as if the Manifest Stream Identifier was wrong. This
state indicates a failed decoding of the TLV space.
3.4.1.8. Packet Digests
Packet digests appended one after the other, aligned to 8-bit
boundaries with 0-bit padding at the end if the bit length of the
digests are not multiples of 8 bits.
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3.5. Transitioning to Other Manifest Streams
It's possible for multiple manifest streams authenticating the same
data stream to be active at the same time. The different manifest
streams can have different hash algorithms, manifest ids, and current
packet sequence numbers for the same data stream. These result in
different sets of packet digests for the same data packets, one
digest per packet per digest profile.
It's necessary sometimes to transition gracefully from one manifest
stream to another. The Refresh Deadline TLV from the manifest is
used to signal to receivers the need to transition.
When a receiver gets a nonzero refresh deadline in a manifest the
sender SHOULD have an alternate manifest stream ready and available,
and the receiver SHOULD learn the alternate manifest stream, join the
new one, and leave the old one before the number of seconds given in
the refresh deadline. After the refresh deadline has expired, a
manifest stream MAY stop transmitting and close connections from the
server side. When multiple manifest-streams are provided in the
metadata, all or all but one SHOULD contain an expire-time, and new
or refreshing receivers SHOULD choose a manifest stream without an
expire-time, or with the latest expire-time if all manifests have an
expire-time.
The receivers SHOULD start the refresh after a random time delay
between now and one half the number of seconds in the deadline field
after the first manifest they receive containing a nonzero refresh
deadline. This time delay is to desynchronize the refresh attempts
in order to spread the spike of load on the DORMS server while
changing manifest profiles during a large multicast event.
4. Transport Considerations
4.1. Overview
AMBI manifests MUST be authenticated, but any transport protocol
providing authentication can be used. This section discusses several
viable options for the use of an authenticating transport, and some
associated design considerations.
TBD: add ALTA to the list when and if it gets further along
[I-D.draft-krose-mboned-alta]. Sending an authenticatable multicast
stream (instead of the below unicast-based proposals) is a worthwhile
goal, else a 1% unicast authentication overhead becomes a new unicast
limit to the scalability.
TBD: probably should add quic also? Or maybe https is sufficient?
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TBD: add a recommendation about scalability, like with DORMS, when
using a unicast hash stream. CDN or other kind of fanout solution
that can scale the delivery, and still generally hit the time window.
4.2. HTTPS
This document defines a new media type 'application/ambi' for use
with HTTPS. URIs in the manifest-transport list with the scheme
'https' use this transport.
An HTTPS stream carrying the 'application/ambi' media type is
composed of a sequence of binary AMBI manifests, sent back to back in
the payload body (payload body is defined in Section 3.3 of
[RFC7230]).
Complete packet digests from partially received manifests MAY be used
by the receiver for authentication of data packets from the multicast
channel, even if the full manifest is not yet delivered.
4.3. TLS
This document defines the new uri scheme 'ambi+tls' for use with TLS
[RFC8446]. URIs in the manifest-transport list with the scheme
'ambi+tls' use this transport.
A TLS stream carrying AMBI manifests is composed of a sequence of
binary AMBI manifests, transmitted back to back.
Complete packet Digests from partially received manifests MAY be used
by the receiver for authentication, even if the full manifest is not
yet delivered.
4.4. DTLS
This document defines the new uri scheme 'ambi+dtls' for use with
DTLS [RFC6347].
Manifests transported with DTLS have the tradeoff (relative to TLS or
HTTPS) that they might be lost and not retransmitted or reordered,
but they will not cause head-of-line blocking or delay in processing
data packets that arrived later. For some applications this is a
worthwhile tradeoff.
Note that loss of a single DTLS packet can result in the loss of
multiple packet digests, which can mean failure to authenticate
multiple data packets.
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DTLS transport for manifests supports one manifest per packet. It's
OPTIONAL to provides for some redundancy in packet digests by
providing overlap in the packet sequence numbers across different
manifests, thereby sending some or all packet digests multiple times
to avoid loss.
Future extensions might define extensions that can provide more
efficient redundancy via FEC. Those future extensions will require a
different URI scheme.
5. Examples
TBD: walk through some examples as soon as we have a build running.
Likely to need some touching up of the spec along the way...
6. YANG Module
6.1. Tree Diagram
The tree diagram below follows the notation defined in [RFC8340].
module: ietf-ambi
augment /dorms:dorms/dorms:metadata/dorms:sender/dorms:group
/dorms:udp-stream:
+--rw ambi
+--rw manifest-stream* [id]
+--rw id uint32
+--rw manifest-stream* [uri]
| +--rw uri inet:uri
+--rw hash-algorithm iha:hash-algorithm-type
+--rw data-hold-time? uint32
+--rw digest-hold-time? uint32
+--rw expiration? yang:date-and-time
augment /dorms:dorms/dorms:metadata/dorms:sender/dorms:group:
+--rw ambi
+--rw manifest-stream* [id]
+--rw id uint32
+--rw manifest-stream* [uri]
| +--rw uri inet:uri
+--rw hash-algorithm iha:hash-algorithm-type
+--rw data-hold-time? uint32
+--rw digest-hold-time? uint32
+--rw expiration? yang:date-and-time
6.2. Module
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<CODE BEGINS>
file ietf-ambi@2022-03-07.yang
module ietf-ambi {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-ambi";
prefix "ambi";
import ietf-dorms {
prefix "dorms";
reference "I-D.jholland-mboned-dorms";
}
import ietf-inet-types {
prefix "inet";
reference "RFC6991 Section 4";
}
import iana-hash-algs {
prefix "iha";
reference "draft-ietf-netconf-crypto-types";
}
import ietf-yang-types {
prefix "yang";
reference "RFC 6991: Common YANG Data Types";
}
organization "IETF";
contact
"Author: Jake Holland
<mailto:jholland@akamai.com>
";
description
"Copyright (c) 2019 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
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for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.
This module contains the definition for the AMBI data types.
It provides metadata for authenticating SSM channels as an
augmentation to DORMS.";
revision 2021-07-08 {
description "Draft version.";
reference
"draft-ietf-mboned-ambi";
}
grouping manifest-stream-definition {
description
"This grouping specifies a manifest stream for
authenticating a multicast data stream with AMBI";
leaf id {
type uint32;
mandatory true;
description
"The Manifest ID referenced in a manifest.";
}
list manifest-stream {
key uri;
leaf uri {
type inet:uri;
mandatory true;
description
"The URI for a stream of manifests.";
}
description "A URI that provides a location for the
manifest stream";
}
leaf hash-algorithm {
type iha:hash-algorithm-type;
mandatory true;
description
"The hash algorithm for the packet hashes within
manifests in this stream.";
}
leaf data-hold-time {
type uint32;
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default 2000;
units "milliseconds";
description
"The number of milliseconds to hold data packets
waiting for a corresponding digest before
discarding";
}
leaf digest-hold-time {
type uint32;
default 10000;
units "milliseconds";
description
"The number of milliseconds to hold packet
digests waiting for a corresponding data packet
before discarding";
}
leaf expiration {
type yang:date-and-time;
description
"The time after which this manifest stream may
stop providing authentication for the data stream.
When not present or empty there is no known expiration.";
}
}
augment
"/dorms:dorms/dorms:metadata/dorms:sender/dorms:group/"+
"dorms:udp-stream" {
description "AMBI extensions for securing UDP multicast.";
container ambi {
description "UDP-layer AMBI container for DORMS extension.";
list manifest-stream {
key id;
description "Manifest stream definition list.";
uses manifest-stream-definition;
}
}
}
augment
"/dorms:dorms/dorms:metadata/dorms:sender/dorms:group" {
description "AMBI extensions for securing IP multicast.";
container ambi {
description "IP-layer AMBI container for DORMS extension.";
list manifest-stream {
key id;
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description "Definition of a manifest stream.";
uses manifest-stream-definition;
}
}
}
}
<CODE ENDS>
7. IANA Considerations
7.1. The YANG Module Names Registry
This document adds one YANG module to the "YANG Module Names"
registry maintained at <https://www.iana.org/assignments/yang-
parameters>. The following registrations are made, per the format in
Section 14 of [RFC6020]:
name: ietf-ambi
namespace: urn:ietf:params:xml:ns:yang:ietf-ambi
prefix: ambi
reference: I-D.draft-jholland-mboned-ambi
7.2. The XML Registry
This document adds the following registration to the "ns" subregistry
of the "IETF XML Registry" defined in [RFC3688], referencing this
document.
URI: urn:ietf:params:xml:ns:yang:ietf-ambi
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
7.3. Media Type
TBD: Register 'application/ambi' according to advice from:
https://www.iana.org/form/media-types (https://www.iana.org/form/
media-types)
TBD: check guidelines in https://tools.ietf.org/html/rfc8126
(https://tools.ietf.org/html/rfc8126)
TBD: comments from Amanda: The first is that the current IANA
Considerations RFC is RFC 8126 rather than 5226. The other point,
which you may be aware of, is that while https://www.iana.org/form/
media-types provides guidance, standards-tree registrations submitted
through RFCs shouldn't be submitted through that form and (unlike
vendor-tree subtypes and standards-tree subtypes documented in other
standards organization specs) won't need to be explicitly approved by
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the IESG-designated experts. Instead, the advice in RFC 6838 is that
media type registrations requested by IETF-stream I-Ds be informally
reviewed on the media-types@iana.org mailing list, which the IESG-
designated experts participate in.
7.4. URI Schemes
7.4.1. TLS
TBD: register 'ambi+tls' as a uri scheme according to advice from:
https://datatracker.ietf.org/doc/html/rfc7595
(https://datatracker.ietf.org/doc/html/rfc7595)
7.4.2. DTLS
TBD: register 'ambi+dtls' as a uri scheme according to advice from:
https://datatracker.ietf.org/doc/html/rfc7595
(https://datatracker.ietf.org/doc/html/rfc7595)
8. Security Considerations
8.1. Predictable Packets
Protocols that have predictable packets run the risk of offline
attacks for hash collisions against those packets. When
authenticating a protocol that might have predictable packets, it's
RECOMMENDED to use a hash function secure against such attacks or to
add content to the packets to make them unpredictable, such as an
Authentication Header ([RFC4302]), or the addition of an ignored
field with random content to the packet payload.
TBD: explain attack from generating malicious packets and then
looking for collisions, as opposed to having to generate a collision
on packet contents that include a sequence number and then hitting a
match.
TBD: follow the rest of the guidelines: https://tools.ietf.org/html/
rfc3552
8.2. Attacks on Side Applications
A multicast receiver subscribes to an (S,G) and if it's a UDP
application, listens on a socket with a port number for packets to
arrive.
UDP applications sometimes bind to an "unspecified" address ("::" or
"0.0.0.0") for a particular UDP port, which will make the appliction
receive and process any packet that arrives on said port.
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Forwarding multicast traffic opens a new practical attack surface
against receivers that have bound sockets using the "unspecified"
address and were operating behind a firewall and/or NAT. Such
applications will receive traffic from the internet only after
sending an outbound packet, and usually only for return packets with
the reversed source and destination port and IP addresses.
Multicast subscription and routing operates at the IP layer, so when
a multicst receive application subscribes to a channel, traffic with
the IP addresses for that channel will start arriving. There is no
selection for the UDP port at the routing layer that prevents
multicast IP traffic from arriving.
When an insecure application with a vulnerability is listening to a
UDP port on an unspecified address, it will receive multicast packets
arriving at the device and with that destination UDP port. Although
the primary problem lies in the insecure application, accepting
multicast subscriptions increases the attack scope against those
applications to include attackers who can inject a packet into a
properly subscribed multicast stream.
It's RECOMMENDED that senders using AMBI to secure their traffic
include all IP traffic that they send in their DORMS metadata
information, and that firewalls using AMBI to provide secure access
to multicast traffic block multicast traffic destined to unsecured
UDP ports on (S,G)s that have AMBI-based security for any traffic.
This mitigation prevents new forwarding of multicast traffic from
providing attackers with a packet inject capability access to new
attack surfaces from pre-existing insecure apps.
9. Acknowledgements
Many thanks to Daniel Franke, Eric Rescorla, Christian Worm
Mortensen, Max Franke, Albert Manfredi, and Amanda Baber for their
very helpful comments and suggestions.
10. References
10.1. Normative References
[I-D.draft-ietf-mboned-dorms]
Holland, J., "Discovery Of Restconf Metadata for Source-
specific multicast", Work in Progress, Internet-Draft,
draft-ietf-mboned-dorms-01, 31 October 2020,
<https://www.ietf.org/archive/id/draft-ietf-mboned-dorms-
01.txt>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
10.2. Informative References
[CVE] MITRE, "Common Vulnerabilities and Exposures", September
1999, <https://cve.mitre.org/>.
[I-D.draft-krose-mboned-alta]
Rose, K. and J. Holland, "Asymmetric Loss-Tolerant
Authentication", Work in Progress, Internet-Draft, draft-
krose-mboned-alta-01, 8 July 2019,
<https://www.ietf.org/archive/id/draft-krose-mboned-alta-
01.txt>.
[I-D.ietf-tsvwg-udp-options]
Touch, J., "Transport Options for UDP", Work in Progress,
Internet-Draft, draft-ietf-tsvwg-udp-options-15, 3 March
2022, <https://www.ietf.org/archive/id/draft-ietf-tsvwg-
udp-options-15.txt>.
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[PathChirp]
Ribeiro, V.J., Riedi, R.H., Baraniuk, R.G., Navratil, J.,
Cottrell, L., Department of Electrical and Computer
Engineering Rice University, and SLAC/SCS-Network
Monitoring, Stanford University, "pathChirp: Efficient
Available Bandwidth Estimation for Network Paths", 2003.
[PathRate] Dovrolis, C., Ramanathan, P., and D. Moore, "Packet
dispersion techniques and a capacity estimation
methodology", IEEE/ACM Transactions on Networking, Volume
12, Issue 6, pp. 963-977. , December 2004.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC4082] Perrig, A., Song, D., Canetti, R., Tygar, J. D., and B.
Briscoe, "Timed Efficient Stream Loss-Tolerant
Authentication (TESLA): Multicast Source Authentication
Transform Introduction", RFC 4082, DOI 10.17487/RFC4082,
June 2005, <https://www.rfc-editor.org/info/rfc4082>.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302,
DOI 10.17487/RFC4302, December 2005,
<https://www.rfc-editor.org/info/rfc4302>.
[RFC4383] Baugher, M. and E. Carrara, "The Use of Timed Efficient
Stream Loss-Tolerant Authentication (TESLA) in the Secure
Real-time Transport Protocol (SRTP)", RFC 4383,
DOI 10.17487/RFC4383, February 2006,
<https://www.rfc-editor.org/info/rfc4383>.
[RFC5776] Roca, V., Francillon, A., and S. Faurite, "Use of Timed
Efficient Stream Loss-Tolerant Authentication (TESLA) in
the Asynchronous Layered Coding (ALC) and NACK-Oriented
Reliable Multicast (NORM) Protocols", RFC 5776,
DOI 10.17487/RFC5776, April 2010,
<https://www.rfc-editor.org/info/rfc5776>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
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[RFC6584] Roca, V., "Simple Authentication Schemes for the
Asynchronous Layered Coding (ALC) and NACK-Oriented
Reliable Multicast (NORM) Protocols", RFC 6584,
DOI 10.17487/RFC6584, April 2012,
<https://www.rfc-editor.org/info/rfc6584>.
[WEBRC] Luby, M. and V. Goyal, "Wave and Equation Based Rate
Control Using Multicast Round Trip Time: Extended Report",
Digital Fountain Technical Report no. DF2002-07-001 ,
September 2002.
Authors' Addresses
Jake Holland
Akamai Technologies, Inc.
150 Broadway
Cambridge, MA 02144,
United States of America
Email: jakeholland.net@gmail.com
Kyle Rose
Akamai Technologies, Inc.
150 Broadway
Cambridge, MA 02144,
United States of America
Email: krose@krose.org
Holland & Rose Expires 8 September 2022 [Page 29]