draft-ietf-mmusic-udptl-dtls-07.txt   draft-ietf-mmusic-udptl-dtls-08.txt 
MMUSIC Working Group C. Holmberg MMUSIC Working Group C. Holmberg
Internet-Draft I. Sedlacek Internet-Draft I. Sedlacek
Intended status: Standards Track Ericsson Intended status: Standards Track Ericsson
Expires: October 18, 2014 G. Salgueiro Expires: December 16, 2014 G. Salgueiro
Cisco Cisco
April 16, 2014 June 14, 2014
UDP Transport Layer (UDPTL) over Datagram Transport Layer Security UDP Transport Layer (UDPTL) over Datagram Transport Layer Security
(DTLS) (DTLS)
draft-ietf-mmusic-udptl-dtls-07 draft-ietf-mmusic-udptl-dtls-08
Abstract Abstract
This document specifies how the UDP Transport Layer (UDPTL) protocol, This document specifies how the UDP Transport Layer (UDPTL) protocol,
the predominant transport protocol for T.38 fax, can be transported the predominant transport protocol for T.38 fax, can be transported
over the Datagram Transport Layer Security (DTLS) protocol, how the over the Datagram Transport Layer Security (DTLS) protocol, how the
usage of UDPTL over DTLS is indicated in the Session Description usage of UDPTL over DTLS is indicated in the Session Description
Protocol (SDP), and how UDPTL over DTLS is negotiated in a session Protocol (SDP), and how UDPTL over DTLS is negotiated in a session
established using the Session Initiation Protocol (SIP). established using the Session Initiation Protocol (SIP).
skipping to change at page 1, line 38 skipping to change at page 1, line 38
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This Internet-Draft will expire on October 18, 2014. This Internet-Draft will expire on December 16, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Secure Channel . . . . . . . . . . . . . . . . . . . . . . . 5 3. Secure Channel . . . . . . . . . . . . . . . . . . . . . . . 5
4. SDP Offerer/Answerer Procedures . . . . . . . . . . . . . . . 5 4. SDP Offerer/Answerer Procedures . . . . . . . . . . . . . . . 5
4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Generating the Initial Offer . . . . . . . . . . . . . . 6 4.2. Generating the Initial Offer . . . . . . . . . . . . . . 6
4.3. Generating the Answer . . . . . . . . . . . . . . . . . . 6 4.3. Generating the Answer . . . . . . . . . . . . . . . . . . 6
4.4. Offerer Processing of the Answer . . . . . . . . . . . . 6 4.4. Offerer Processing of the Answer . . . . . . . . . . . . 7
4.5. Modifying the Session . . . . . . . . . . . . . . . . . . 7 4.5. Modifying the Session . . . . . . . . . . . . . . . . . . 7
5. Miscellaneous Considerations . . . . . . . . . . . . . . . . 7 5. Miscellaneous Considerations . . . . . . . . . . . . . . . . 7
5.1. Anonymous Calls . . . . . . . . . . . . . . . . . . . . . 7 5.1. Anonymous Calls . . . . . . . . . . . . . . . . . . . . . 7
5.2. NAT Traversal . . . . . . . . . . . . . . . . . . . . . . 7 5.2. NAT Traversal . . . . . . . . . . . . . . . . . . . . . . 7
5.2.1. ICE Usage . . . . . . . . . . . . . . . . . . . . . . 7 5.2.1. ICE Usage . . . . . . . . . . . . . . . . . . . . . . 7
5.2.2. STUN Interaction . . . . . . . . . . . . . . . . . . 7 5.2.2. STUN Interaction . . . . . . . . . . . . . . . . . . 8
5.3. Rekeying . . . . . . . . . . . . . . . . . . . . . . . . 8 5.3. Rekeying . . . . . . . . . . . . . . . . . . . . . . . . 8
5.4. Compatibility With UDPTL over UDP . . . . . . . . . . . . 8 5.4. Compatibility With UDPTL over UDP . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
9. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 10 9. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . 12 10.1. Normative References . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . 13 10.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 13 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 14
A.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 13 A.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 14
A.2. Basic Message Flow . . . . . . . . . . . . . . . . . . . 14 A.2. Basic Message Flow . . . . . . . . . . . . . . . . . . . 14
A.3. Message Flow Of T.38 Fax Replacing Audio Media Stream in A.3. Message Flow Of T.38 Fax Replacing Audio Media Stream in
An Existing Audio-Only Session . . . . . . . . . . . . . 19 An Existing Audio-Only Session . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
While it is possible to transmit highly sensitive documents using While it is possible to transmit highly sensitive documents using
traditional telephony encryption devices, secure fax on the Public traditional telephony encryption devices, secure fax on the Public
Switched Telephone Network (PSTN) was never widely considered or Switched Telephone Network (PSTN) was never widely considered or
prioritized. This was mainly because of the challenges involved with prioritized. This was mainly because of the challenges involved with
malevolent physical access to telephony equipment. As real-time malevolent physical access to telephony equipment. As real-time
communications transition to IP networks, where information might communications transition to IP networks, where information might
potentially be intercepted or spoofed, an appropriate level of potentially be intercepted or spoofed, an appropriate level of
security for fax that offers integrity and confidentiality protection security for fax that offers integrity and confidentiality protection
is vital. is vital.
The overwhelmingly predominant fax transport protocol is UDPTL-based The overwhelmingly predominant fax transport protocol is UDPTL-based,
[ITU.T38.2010]. The protocol stack for fax transport using UDPTL is as described in section 9.1 of [ITU.T38.2010]. The protocol stack
shown in Figure 1. for fax transport using UDPTL is shown in Figure 1.
+-----------------------------+ +-----------------------------+
| Internet facsimile protocol | | Internet facsimile protocol |
+-----------------------------+ +-----------------------------+
| UDPTL | | UDPTL |
+-----------------------------+ +-----------------------------+
| UDP | | UDP |
+-----------------------------+ +-----------------------------+
| IP | | IP |
+-----------------------------+ +-----------------------------+
Figure 1: Protocol stack for UDPTL over UDP Figure 1: Protocol stack for UDPTL over UDP
Implementations exist today for securing this fax transport type. The following mechanisms are available for securing fax:
Some of these mechanisms are:
o [ITU.T30.2005] Annex H specifies integrity and confidentiality o [ITU.T30.2005] Annex H specifies a transport protocol-independent
protection of fax in the application layer, independent of application-layer integrity and confidentiality protection of fax
protocol for fax transport. based on the RSA algorithm for use with the T.30 telephony
protocol by Group 3 facsimile equipment (G3FE).
o [ITU.T38.2010] specifies fax transport over RTP/SAVP which enables o [ITU.T38.2010] specifies fax transport over RTP/SAVP which enables
integrity and confidentiality protection of fax in IP network. integrity and confidentiality protection of fax in IP network.
Despite these mechanisms to secure fax, there is no transport layer Both of these mechanisms have been available for many years and never
security offering integrity and confidentiality protection for UDPTL. gained any significant adoption in the market. This has prompted an
This issue was addressed in a study by the 3rd Generation Partnership effort to develop an open standards-based approach to secure fax
Project (3GPP) on how to provide secure fax in the IP Multimedia communications over an IP-based transport.
Subsystem (IMS). They concluded that secure fax shall be transported
using UDPTL over DTLS. Telephony-based protocols like T.30 offer application-level security
options like the RSA-based approached detailed in Annex H of the T.30
specification. The problem is that it is very sparingly implemented
and not enforced at the transport level.
It is worth noting that while T.38 over RTP offers a very viable
option for such standards-based IP security solution using SRTP, this
fax over IP transport never gained any traction in the market place
and accounts for a negligible percentage of fax over IP
implementations.
Thus, security mechanisms offering integrity and confidentiality
protection should be limited to UDPTL-based fax transport, which is
the only broad-based fax over IP solution. The 3rd Generation
Partnership Project (3GPP) launched a study on how best to provide
secure fax in the IP Multimedia Subsystem (IMS) for UDPTL. Results
of the study confirmed that this security was best achieved by using
UDPTL over DTLS.
This document specifies fax transport using UDPTL over DTLS This document specifies fax transport using UDPTL over DTLS
[RFC6347], which enables integrity and confidentiality protection of [RFC6347], which enables integrity and confidentiality protection of
fax in IP networks. The protocol stack which enhances fax transport fax in IP networks. The protocol stack which enhances fax transport
to offer integrity and confidentiality using UDPTL over DTLS is shown to offer integrity and confidentiality using UDPTL over DTLS is shown
in Figure 2. in Figure 2.
+-----------------------------+ +-----------------------------+
| Internet facsimile protocol | | Internet facsimile protocol |
+-----------------------------+ +-----------------------------+
skipping to change at page 4, line 21 skipping to change at page 4, line 27
+-----------------------------+ +-----------------------------+
| UDP | | UDP |
+-----------------------------+ +-----------------------------+
| IP | | IP |
+-----------------------------+ +-----------------------------+
Figure 2: Protocol stack for UDPTL over DTLS over UDP Figure 2: Protocol stack for UDPTL over DTLS over UDP
The primary motivations for the mechanism in this document are: The primary motivations for the mechanism in this document are:
o The design of DTLS [RFC6347] is clearly defined, well understood o The design of DTLS [RFC6347] is clearly defined and well
and implementations are widely available. understood and implementations are widely available.
o No DTLS extensions are required in order to enable UDPTL transport o No DTLS extensions are required in order to enable UDPTL transport
over DTLS. over DTLS.
o Fax transport using UDPTL over DTLS only requires insertion of the o Fax transport using UDPTL over DTLS only requires insertion of the
DTLS layer between the UDPTL layer and the UDP layer, as shown in DTLS layer between the UDPTL layer and the UDP layer, as shown in
Figure 2. The UDPTL layer and the layers above the UDPTL layer Figure 2. The UDPTL layer and the layers above the UDPTL layer
require no modifications. require no modifications.
o UDPTL [ITU.T38.2010] is by far the most widely deployed fax o UDPTL [ITU.T38.2010] is by far the most widely deployed fax
transport protocol in IP networks. transport protocol in IP networks.
o 3GPP and the IP fax community need a mechanism to transport UDPTL o 3GPP and the IP fax community need a mechanism to transport UDPTL
over DTLS in order to provide secure fax in SIP-based networks over DTLS in order to provide secure fax in SIP-based networks
skipping to change at page 5, line 26 skipping to change at page 5, line 31
usage, we use the term "connection" when what's being referred to is usage, we use the term "connection" when what's being referred to is
a multimedia stream that is not specifically DTLS. a multimedia stream that is not specifically DTLS.
3. Secure Channel 3. Secure Channel
The UDPTL over DTLS media stream is negotiated using the SDP offer/ The UDPTL over DTLS media stream is negotiated using the SDP offer/
answer mechanism [RFC3264]. See Section 4 for more details. answer mechanism [RFC3264]. See Section 4 for more details.
DTLS is used as specified in [RFC6347]. Once the DTLS handshake is DTLS is used as specified in [RFC6347]. Once the DTLS handshake is
successfully completed (in order to prevent facsimile data from being successfully completed (in order to prevent facsimile data from being
transmitted insecurely), the UDPTL packets SHALL be transported in transmitted insecurely), the UDPTL packets MUST be transported in
DTLS record layer "application_data" packets. DTLS record layer "application_data" packets.
4. SDP Offerer/Answerer Procedures 4. SDP Offerer/Answerer Procedures
4.1. General 4.1. General
An endpoint (i.e. both the offerer and the answerer) MUST create an An endpoint (i.e. both the offerer and the answerer) MUST create an
SDP media description ("m=" line) for each UDPTL over DTLS media SDP media description ("m=" line) for each UDPTL over DTLS media
stream, and MUST assign a UDP/TLS/UDPTL value (see Table 1) to the stream, and MUST assign a UDP/TLS/UDPTL value (see Table 1) to the
"proto" field of the "m=" line. "proto" field of the "m=" line.
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described in this section. described in this section.
The endpoint MUST NOT use the SDP "connection" attribute [RFC4145]. The endpoint MUST NOT use the SDP "connection" attribute [RFC4145].
In order to negotiate the TLS roles for the UDPTL over DTLS transport In order to negotiate the TLS roles for the UDPTL over DTLS transport
connection, the endpoint MUST use the SDP "setup" attribute connection, the endpoint MUST use the SDP "setup" attribute
[RFC4145]. [RFC4145].
If the endpoint supports, and is willing to use, a cipher suite with If the endpoint supports, and is willing to use, a cipher suite with
an associated certificate, the endpoint MUST include an SDP an associated certificate, the endpoint MUST include an SDP
"fingerprint" attribute [RFC4572]. "fingerprint" attribute [RFC4572]. The endpoint MUST support SHA-256
for generating and verifying the SDP "fingerprint" attribute value.
The use of SHA-256 is preferred. UPDPTL over DTLS, at a minimum,
MUST support TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 and MUST support
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256. UDPTL over DTLS MUST prefer
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 and any other Perfect Forward
Secrecy (PFS) cipher suites over non-PFS cipher suites.
Implementations SHOULD disable TLS-level compression.
If a cipher suite with an associated certificate is selected during If a cipher suite with an associated certificate is selected during
the DTLS handshake, the certificate received during the DTLS the DTLS handshake, the certificate received during the DTLS
handshake MUST match the fingerprint received in the SDP handshake MUST match the fingerprint received in the SDP
"fingerprint" attribute. If the fingerprint does not match the "fingerprint" attribute. If the fingerprint does not match the
hashed certificate, then the endpoint MUST tear down the media hashed certificate, then the endpoint MUST tear down the media
session immediately. Note that it is permissible to wait until the session immediately. Note that it is permissible to wait until the
other side's fingerprint has been received before establishing the other side's fingerprint has been received before establishing the
connection; however, this may have undesirable latency effects. connection; however, this may have undesirable latency effects.
4.2. Generating the Initial Offer 4.2. Generating the Initial Offer
The offerer SHOULD assign the SDP "setup" attribute with a value of The offerer SHOULD assign the SDP "setup" attribute with a value of
"actpass". Alternatively, the offerer MAY assign the SDP "setup" "actpass", unless the offerer insists on being either the sender or
attribute with a value of "active" or "passive". The offerer MUST receiver of the DTLS ClientHello message, in which case the offerer
NOT assign an SDP "setup" attribute with a "holdconn" value. can use either a value of "active" (the offerer will be the sender of
ClientHello) or "passive" (the offerer will be the receiver of
ClientHello). The offerer MUST NOT assign an SDP "setup" attribute
with a "holdconn" value.
If the offerer assigns the SDP "setup" attribute with a value of If the offerer assigns the SDP "setup" attribute with a value of
"actpass" or "passive", the offerer MUST be prepared to receive a "actpass" or "passive", the offerer MUST be prepared to receive a
DTLS ClientHello message before it receives the SDP answer. DTLS ClientHello message before it receives the SDP answer.
4.3. Generating the Answer 4.3. Generating the Answer
If the answerer accepts the offered UDPTL over DTLS transport If the answerer accepts the offered UDPTL over DTLS transport
connection, in the associated SDP answer the answerer MUST assign an connection, in the associated SDP answer the answerer MUST assign an
SDP "setup" attribute with a value of either "active" or "passive", SDP "setup" attribute with a value of either "active" or "passive",
according to the procedures in [RFC4145]. The answerer MUST NOT according to the procedures in [RFC4145]. The answerer MUST NOT
assign an SDP "setup" attribute with a value of "holdconn". assign an SDP "setup" attribute with a value of "holdconn".
If the answerer assigns an SDP "setup" attribute with a value of If the answerer assigns an SDP "setup" attribute with a value of
"active" value, the answerer MUST initiate a DTLS handshake by "active" value, the answerer MUST initiate a DTLS handshake by
sending a DTLS ClientHello message on the negotiated media stream, sending a DTLS ClientHello message on the negotiated media stream,
towards the IP address and port of the offerer. towards the IP address and port of the offerer.
4.4. Offerer Processing of the Answer 4.4. Offerer Processing of the Answer
When the offerer receives an SDP answer and, if the offerer ends up When the offerer receives an SDP answer, if the offerer ends up being
being active it MUST initiate a DTLS handshake by sending a DTLS active it MUST initiate a DTLS handshake by sending a DTLS
ClientHello message on the negotiated media stream, towards the IP ClientHello message on the negotiated media stream, towards the IP
address and port of the answerer. address and port of the answerer.
4.5. Modifying the Session 4.5. Modifying the Session
Once an offer/answer exchange has been completed, either endpoint MAY Once an offer/answer exchange has been completed, either endpoint MAY
send a new offer in order to modify the session. The endpoints can send a new offer in order to modify the session. The endpoints can
reuse the existing DTLS association if the key fingerprint values and reuse the existing DTLS association if the key fingerprint values and
transport parameters indicated by each endpoint are unchanged. transport parameters indicated by each endpoint are unchanged.
Otherwise, following the rules as for the initial offer/answer Otherwise, following the rules as for the initial offer/answer
exchange, the endpoints can negotiate and create a new DTLS exchange, the endpoints can negotiate and create a new DTLS
association and, once created, delete the previous DTLS association, association and, once created, delete the previous DTLS association,
following the same rules of for the initial offer/answer exchange. following the same rules for the initial offer/answer exchange. Each
Each endpoint needs to be prepared to receive data on both the new endpoint needs to be prepared to receive data on both the new and old
and old DTLS associations, as long as both are alive. DTLS associations, as long as both are alive.
5. Miscellaneous Considerations 5. Miscellaneous Considerations
5.1. Anonymous Calls 5.1. Anonymous Calls
When making anonymous calls, a new self-signed certificate SHOULD be When making anonymous calls, a new self-signed certificate SHOULD be
used for each call and attributes inside the certificate SHALL NOT used for each call and attributes inside the certificate MUST NOT
contain information that either allows correlation or identification contain information that either allows correlation or identification
of the user making anonymous calls. This is particularly important of the user making anonymous calls. This is particularly important
for the subjectAltName and commonName attributes. for the subjectAltName and commonName attributes.
5.2. NAT Traversal 5.2. NAT Traversal
5.2.1. ICE Usage 5.2.1. ICE Usage
When ICE [RFC5245] is being used, the ICE connectivity checks are When ICE [RFC5245] is being used, the ICE connectivity checks are
performed before the DTLS handshake begins. Note that if aggressive performed before the DTLS handshake begins. Note that if aggressive
skipping to change at page 7, line 48 skipping to change at page 8, line 11
handshake even if there are multiple valid candidate pairs. Note handshake even if there are multiple valid candidate pairs. Note
that this may mean adjusting the endpoint IP addresses if the that this may mean adjusting the endpoint IP addresses if the
selected candidate pair shifts, just as if the DTLS packets were an selected candidate pair shifts, just as if the DTLS packets were an
ordinary media stream. In case of an ICE restart, the DTLS handshake ordinary media stream. In case of an ICE restart, the DTLS handshake
procedure is repeated and a new DTLS association is created. Once procedure is repeated and a new DTLS association is created. Once
the DTLS handshake is completed ,and the new DTLS association has the DTLS handshake is completed ,and the new DTLS association has
been created, the previous DTLS association is deleted. been created, the previous DTLS association is deleted.
5.2.2. STUN Interaction 5.2.2. STUN Interaction
The UA SHALL send the STUN packets [RFC5389] directly over UDP, not The UA MUST send the STUN packets [RFC5389] directly over UDP, not
over DTLS. over DTLS.
The UA MUST demultiplex packets arriving on the IP address and port The UA MUST support the following mechanism for demultiplexing
associated with the DTLS association, e.g. as follows: packets arriving on the IP address and port associated with the DTLS
association:
o If the value of the first byte of the packet is 0 or 1, then the o If the value of the first byte of the packet is 0 or 1, then the
packet is STUN. packet is STUN.
o If the value of the first byte of the packet is between 20 and 63 o If the value of the first byte of the packet is between 20 and 63
(inclusive), the packet is DTLS. (inclusive), the packet is DTLS.
5.3. Rekeying 5.3. Rekeying
After the DTLS handshake caused by rekeying has completed, because of During rekeying, packets protected by the previous set of keys can
possible packet reordering on the wire, packets protected by the arrive after the DTLS handshake caused by rekeying has completed,
previous set of keys can arrive. To compensate for this fact, because packets can be reordered on the wire. To compensate for this
receivers MUST maintain both sets of keys for some time in order to fact, receivers MUST maintain both sets of keys for some time in
be able to decrypt and verify older packets. The duration of order to be able to decrypt and verify older packets. The duration
maintaining the previous set of keys after the finish of the DTLS of maintaining the previous set of keys after the finish of the DTLS
handshake is out of scope for this document. handshake is out of scope for this document.
5.4. Compatibility With UDPTL over UDP 5.4. Compatibility With UDPTL over UDP
If a user requires fax to be transported securely using UDPTL over If a user requires fax to be transported securely using UDPTL over
DTLS, and if the remote user does not support UDPTL over DTLS, then a DTLS, and if the remote user does not support UDPTL over DTLS, then a
fax media stream cannot be established. fax media stream cannot be established.
If a user prefers fax to be transported securely using UDPTL over If a user prefers fax to be transported securely using UDPTL over
DTLS, but is willing to transport the fax insecurely in case the DTLS, but is willing to transport the fax insecurely in case the
skipping to change at page 9, line 5 skipping to change at page 9, line 20
DTLS media stream negotiated using SIP/SDP requires a mechanism to DTLS media stream negotiated using SIP/SDP requires a mechanism to
ensure that the certificate received via DTLS was issued by the ensure that the certificate received via DTLS was issued by the
remote party of the SIP session. remote party of the SIP session.
The standard DTLS strategy for authenticating the communicating The standard DTLS strategy for authenticating the communicating
parties is to give the server (and optionally the client) a PKIX parties is to give the server (and optionally the client) a PKIX
[RFC5280] certificate. The client then verifies the certificate and [RFC5280] certificate. The client then verifies the certificate and
checks that the name in the certificate matches the server's domain checks that the name in the certificate matches the server's domain
name. This works because there are a relatively small number of name. This works because there are a relatively small number of
servers with well-defined names; a situation that does not usually servers and the cost for issuing and deploying PKIX certificates can
occur in the VoIP context. be justified. Issuing and deploying PKIX certificates to all clients
is not realistic in most deployment scenarios.
The design described in this document is intended to leverage the The design described in this document is intended to leverage the
integrity protection of the SIP signaling, while not requiring integrity protection of the SIP signaling, while not requiring
confidentiality. As long as each side of the connection can verify confidentiality. As long as each side of the connection can verify
the integrity of the SDP received from the other side, then the DTLS the integrity of the SDP received from the other side, then the DTLS
handshake cannot be hijacked via a man-in-the-middle attack. This handshake cannot be hijacked via a man-in-the-middle attack. This
integrity protection is easily provided by the caller to the callee integrity protection is easily provided by the caller to the callee
via the SIP Identity [RFC4474] mechanism. Other mechanisms, such as via the SIP Identity [RFC4474] mechanism. Other mechanisms, such as
the S/MIME mechanism [RFC3261], or perhaps future mechanisms yet to the S/MIME mechanism [RFC3261], or perhaps future mechanisms yet to
be specified could also serve this purpose. be specified could also serve this purpose.
skipping to change at page 9, line 45 skipping to change at page 10, line 19
+-------+---------------+------------+ +-------+---------------+------------+
Table 1: SDP "proto" field values Table 1: SDP "proto" field values
[RFC EDITOR NOTE: Please replace RFC-XXXX with the RFC number of this [RFC EDITOR NOTE: Please replace RFC-XXXX with the RFC number of this
document.] document.]
8. Acknowledgments 8. Acknowledgments
Special thanks to Peter Dawes, who provided comments on the initial Special thanks to Peter Dawes, who provided comments on the initial
version of the draft, and to Paul E. Jones, James Rafferty, Albrecht version of the draft, and to Paul E. Jones, James Rafferty, Albrecht
Schwarz, Oscar Ohlsson, David Hanes, Adam Gensler, Ari Keranen and Schwarz, Oscar Ohlsson, David Hanes, Adam Gensler, Ari Keranen,
Flemming Andreasen who provided valuable feedback and input on the Flemming Andreasen and John Mattsson who provided valuable feedback
MMUSIC mailing list. and input. Barry Leiba, Spencer Dawkins, Pete Resnick, Kathleen
Moriarty and Stephen Farrell provided valuable feedback during the
IESG review. Thanks to Scott Brim for performing the Gen-ART review.
Thanks to Alissa Cooper for her help as sponsoring Area Director.
9. Change Log 9. Change Log
[RFC EDITOR NOTE: Please remove this section when publishing] [RFC EDITOR NOTE: Please remove this section when publishing]
Changes from draft-ietf-mmusic-udptl-dtls-07
o Changes based on IESG comments by Barry Leiba:
o - SHALL replaced with MUST.
o - Text modifications in sections 4.2, 4.4, 5.2.2, 5.3 and 6.
o Changes based on IESG comments by Pete Resnick and Kathleen
Moriarty:
o - Additional text on existing mechanisms for securing fax in
section 1.
o Changes based on IESG comments by Stephen Farrell:
o - Added text regarding MTI cipher suites.
Changes from draft-ietf-mmusic-udptl-dtls-06 Changes from draft-ietf-mmusic-udptl-dtls-06
o Changes based on WGLC comments by Paul Kyzivat o Changes based on WGLC comments by Paul Kyzivat
o - Indicating that, when a new and an old DTLS association exist, o - Indicating that, when a new and an old DTLS association exist,
each endpoint needs to be prepared to receive data on both. each endpoint needs to be prepared to receive data on both.
o - Editorial nit. o - Editorial nit.
Changes from draft-ietf-mmusic-udptl-dtls-05 Changes from draft-ietf-mmusic-udptl-dtls-05
o Changes based on comments by Flemming Andreasen o Changes based on comments by Flemming Andreasen
skipping to change at page 11, line 4 skipping to change at page 11, line 36
correlation/identification of users. correlation/identification of users.
o Changes based on comments by Ari Keranen (http://www.ietf.org/ o Changes based on comments by Ari Keranen (http://www.ietf.org/
mail-archive/web/mmusic/current/msg12966.html) mail-archive/web/mmusic/current/msg12966.html)
o -Informative reference to RFC 5246 added. o -Informative reference to RFC 5246 added.
o -Re-naming of sections 4.2.1 and 4.2.2. o -Re-naming of sections 4.2.1 and 4.2.2.
o -Clarifying that documented STUN/DTLS demux mechanism is only one o -Clarifying that documented STUN/DTLS demux mechanism is only one
way of doing the demux. way of doing the demux.
o -Editorial corrections. o -Editorial corrections.
Changes from draft-ietf-mmusic-udptl-dtls-02 Changes from draft-ietf-mmusic-udptl-dtls-02
o Editorial comments based on review comments by James Rafferty o Editorial comments based on review comments by James Rafferty
(http://www.ietf.org/mail-archive/web/mmusic/current/ (http://www.ietf.org/mail-archive/web/mmusic/current/
msg12890.html) msg12890.html)
o Editorial comments based on review comments by David Hanes (http:/ o Editorial comments based on review comments by David Hanes
/www.ietf.org/mail-archive/web/mmusic/current/msg12886.html) (http://www.ietf.org/mail-archive/web/mmusic/current/
msg12886.html)
o Editorial comments based on review comments by Oscar Ohlsson o Editorial comments based on review comments by Oscar Ohlsson
(http://www.ietf.org/mail-archive/web/mmusic/current/ (http://www.ietf.org/mail-archive/web/mmusic/current/
msg12882.html) msg12882.html)
o Editorial comments based on review comments by Albrecht Schwartz o Editorial comments based on review comments by Albrecht Schwartz
(http://www.ietf.org/mail-archive/web/mmusic/current/ (http://www.ietf.org/mail-archive/web/mmusic/current/
msg12900.html) msg12900.html)
Changes from draft-ietf-mmusic-udptl-dtls-01 Changes from draft-ietf-mmusic-udptl-dtls-01
o Usage of the SDP fingerprint attribute depends on whether a cipher o Usage of the SDP fingerprint attribute depends on whether a cipher
suite with an associated certificate is used. suite with an associated certificate is used.
o Editor's note in section 4.2 removed. Procedure text added. o Editor's note in section 4.2 removed. Procedure text added.
Changes from draft-ietf-mmusic-udptl-dtls-00 Changes from draft-ietf-mmusic-udptl-dtls-00
o SDP offerer is allowed to assign an a=setup:active or o SDP offerer is allowed to assign an a=setup:active or
a=setup:passive value, in addition to the recommended a=setup:passive value, in addition to the recommended
a=setup:actpass (http://www.ietf.org/mail-archive/web/mmusic/ a=setup:actpass (http://www.ietf.org/mail-
current/msg12331.html). archive/web/mmusic/current/msg12331.html).
o The example for secure fax replacing audio stream in audio-only o The example for secure fax replacing audio stream in audio-only
session added (http://www.ietf.org/mail-archive/web/mmusic/current session added (http://www.ietf.org/mail-
/msg12428.html). archive/web/mmusic/current/msg12428.html).
o Editor's note on the connection attribute resolved by prohibiting o Editor's note on the connection attribute resolved by prohibiting
usage of the SDP connection attribute (http://www.ietf.org/mail- usage of the SDP connection attribute (http://www.ietf.org/mail-
archive/web/mmusic/current/msg12772.html). archive/web/mmusic/current/msg12772.html).
o Editorial corrections. o Editorial corrections.
Changes from draft-holmberg-mmusic-udptl-dtls-02 Changes from draft-holmberg-mmusic-udptl-dtls-02
o Milestone adopted - draft-ietf-mmusic version of the draft o Milestone adopted - draft-ietf-mmusic version of the draft
submitted. submitted.
 End of changes. 32 change blocks. 
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