draft-ietf-perc-double-06.txt   draft-ietf-perc-double-07.txt 
Network Working Group C. Jennings Network Working Group C. Jennings
Internet-Draft P. Jones Internet-Draft P. Jones
Intended status: Standards Track R. Barnes Intended status: Standards Track R. Barnes
Expires: February 9, 2018 Cisco Systems Expires: March 5, 2018 Cisco Systems
A. Roach A. Roach
Mozilla Mozilla
August 8, 2017 September 1, 2017
SRTP Double Encryption Procedures SRTP Double Encryption Procedures
draft-ietf-perc-double-06 draft-ietf-perc-double-07
Abstract Abstract
In some conferencing scenarios, it is desirable for an intermediary In some conferencing scenarios, it is desirable for an intermediary
to be able to manipulate some RTP parameters, while still providing to be able to manipulate some RTP parameters, while still providing
strong end-to-end security guarantees. This document defines SRTP strong end-to-end security guarantees. This document defines SRTP
procedures that use two separate but related cryptographic operations procedures that use two separate but related cryptographic operations
to provide hop-by-hop and end-to-end security guarantees. Both the to provide hop-by-hop and end-to-end security guarantees. Both the
end-to-end and hop-by-hop cryptographic algorithms can utilize an end-to-end and hop-by-hop cryptographic algorithms can utilize an
authenticated encryption with associated data scheme or take authenticated encryption with associated data scheme or take
skipping to change at page 1, line 40 skipping to change at page 1, line 40
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 9, 2018. This Internet-Draft will expire on March 5, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 9, line 23 skipping to change at page 9, line 23
7.2. RED 7.2. RED
TODO - Add text to explain how to use RED as described in Option A of TODO - Add text to explain how to use RED as described in Option A of
slides presented at IETF 99. slides presented at IETF 99.
7.3. FEC 7.3. FEC
When using Flex FEC [I-D.ietf-payload-flexible-fec-scheme] with When using Flex FEC [I-D.ietf-payload-flexible-fec-scheme] with
double, the negotiation of double for the crypto is the out of band double, the negotiation of double for the crypto is the out of band
signaling that indicates that the repair packets MUST use the order signalling that indicates that the repair packets MUST use the order
of operations of SRTP followed by FEC when encrypting. This is to of operations of SRTP followed by FEC when encrypting. This is to
ensure that the original media is not reveled to the Media ensure that the original media is not revealed to the Media
Distributor but at the same time allow the Media Distributor to Distributor but at the same time allow the Media Distributor to
repair media. When encrypting a packet that contains the Flex FEC repair media. When encrypting a packet that contains the Flex FEC
data, which is already encrypted, it MUST be encrypted in repair mode data, which is already encrypted, it MUST be encrypted in repair mode
packet. packet.
The algorithm recommend in [I-D.ietf-rtcweb-fec] for repair of video The algorithm recommend in [I-D.ietf-rtcweb-fec] for repair of video
is Flex FEC [I-D.ietf-payload-flexible-fec-scheme]. Note that for is Flex FEC [I-D.ietf-payload-flexible-fec-scheme]. Note that for
interoperability with WebRTC, [I-D.ietf-rtcweb-fec] recommends not interoperability with WebRTC, [I-D.ietf-rtcweb-fec] recommends not
using additional FEC only m-line in SDP for the repair packets. using additional FEC only m-line in SDP for the repair packets.
7.4. DTMF 7.4. DTMF
When DTMF is sent with [RFC4733], it is end-to-end encrypted and the When DTMF is sent with [RFC4733], it is end-to-end encrypted and the
relay can not read it so it can not be used to controll the relay. relay can not read it so it can not be used to control the relay.
Other out of band methods to controll the relay need to be used Other out of band methods to control the relay need to be used
instead. instead.
8. Recommended Inner and Outer Cryptographic Algorithms 8. Recommended Inner and Outer Cryptographic Algorithms
This specification recommends and defines AES-GCM as both the inner This specification recommends and defines AES-GCM as both the inner
and outer cryptographic algorithms, identified as and outer cryptographic algorithms, identified as
DOUBLE_AEAD_AES_128_GCM_AEAD_AES_128_GCM and DOUBLE_AEAD_AES_128_GCM_AEAD_AES_128_GCM and
DOUBLE_AEAD_AES_256_GCM_AEAD_AES_256_GCM. These algorithm provide DOUBLE_AEAD_AES_256_GCM_AEAD_AES_256_GCM. These algorithm provide
for authenticated encryption and will consume additional processing for authenticated encryption and will consume additional processing
time double-encrypting for hop-by-hop and end-to-end. However, the time double-encrypting for hop-by-hop and end-to-end. However, the
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auth_tag_length: N/A auth_tag_length: N/A
maximum lifetime: at most 2^31 SRTCP packets and maximum lifetime: at most 2^31 SRTCP packets and
at most 2^48 SRTP packets at most 2^48 SRTP packets
The first half of the key and salt is used for the inner (end-to-end) The first half of the key and salt is used for the inner (end-to-end)
algorithm and the second half is used for the outer (hop-by-hop) algorithm and the second half is used for the outer (hop-by-hop)
algorithm. algorithm.
11. Acknowledgments 11. Acknowledgments
Many thanks to Richard Barnes for sending significant text for this Thank you for reviews and improvements to this specification from
specification. Thank you for reviews and improvements from David Alex Gouaillard, David Benham, Magnus Westerlund, Nils Ohlmeier, Paul
Benham, Paul Jones, Suhas Nandakumar, Nils Ohlmeier, and Magnus Jones, Roni Even, and Suhas Nandakumar. In addition, thank you to
Westerlund. Sergio Garcia Murillo proposed the change of transporting the OHB
information in the RTP payload instead of the RTP header.
12. References 12. References
12.1. Normative References 12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119,
RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc2119>. editor.org/info/rfc2119>.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004, RFC 3711, DOI 10.17487/RFC3711, March 2004,
<http://www.rfc-editor.org/info/rfc3711>. <https://www.rfc-editor.org/info/rfc3711>.
[RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP
Header Extensions", RFC 5285, DOI 10.17487/RFC5285, July Header Extensions", RFC 5285, DOI 10.17487/RFC5285, July
2008, <http://www.rfc-editor.org/info/rfc5285>. 2008, <https://www.rfc-editor.org/info/rfc5285>.
[RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer [RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer
Security (DTLS) Extension to Establish Keys for the Secure Security (DTLS) Extension to Establish Keys for the Secure
Real-time Transport Protocol (SRTP)", RFC 5764, DOI Real-time Transport Protocol (SRTP)", RFC 5764,
10.17487/RFC5764, May 2010, DOI 10.17487/RFC5764, May 2010, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc5764>. editor.org/info/rfc5764>.
[RFC6904] Lennox, J., "Encryption of Header Extensions in the Secure [RFC6904] Lennox, J., "Encryption of Header Extensions in the Secure
Real-time Transport Protocol (SRTP)", RFC 6904, DOI Real-time Transport Protocol (SRTP)", RFC 6904,
10.17487/RFC6904, April 2013, DOI 10.17487/RFC6904, April 2013, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc6904>. editor.org/info/rfc6904>.
[RFC7714] McGrew, D. and K. Igoe, "AES-GCM Authenticated Encryption [RFC7714] McGrew, D. and K. Igoe, "AES-GCM Authenticated Encryption
in the Secure Real-time Transport Protocol (SRTP)", RFC in the Secure Real-time Transport Protocol (SRTP)",
7714, DOI 10.17487/RFC7714, December 2015, RFC 7714, DOI 10.17487/RFC7714, December 2015,
<http://www.rfc-editor.org/info/rfc7714>. <https://www.rfc-editor.org/info/rfc7714>.
12.2. Informative References 12.2. Informative References
[I-D.ietf-payload-flexible-fec-scheme] [I-D.ietf-payload-flexible-fec-scheme]
Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP
Payload Format for Flexible Forward Error Correction Payload Format for Flexible Forward Error Correction
(FEC)", draft-ietf-payload-flexible-fec-scheme-05 (work in (FEC)", draft-ietf-payload-flexible-fec-scheme-05 (work in
progress), July 2017. progress), July 2017.
[I-D.ietf-perc-dtls-tunnel] [I-D.ietf-perc-dtls-tunnel]
skipping to change at page 14, line 23 skipping to change at page 14, line 23
"Encrypted Key Transport for DTLS and Secure RTP", draft- "Encrypted Key Transport for DTLS and Secure RTP", draft-
ietf-perc-srtp-ekt-diet-05 (work in progress), June 2017. ietf-perc-srtp-ekt-diet-05 (work in progress), June 2017.
[I-D.ietf-rtcweb-fec] [I-D.ietf-rtcweb-fec]
Uberti, J., "WebRTC Forward Error Correction Uberti, J., "WebRTC Forward Error Correction
Requirements", draft-ietf-rtcweb-fec-06 (work in Requirements", draft-ietf-rtcweb-fec-06 (work in
progress), July 2017. progress), July 2017.
[RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. [RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
Hakenberg, "RTP Retransmission Payload Format", RFC 4588, Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
DOI 10.17487/RFC4588, July 2006, DOI 10.17487/RFC4588, July 2006, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc4588>. editor.org/info/rfc4588>.
[RFC4733] Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF [RFC4733] Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF
Digits, Telephony Tones, and Telephony Signals", RFC 4733, Digits, Telephony Tones, and Telephony Signals", RFC 4733,
DOI 10.17487/RFC4733, December 2006, DOI 10.17487/RFC4733, December 2006, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc4733>. editor.org/info/rfc4733>.
[RFC6465] Ivov, E., Ed., Marocco, E., Ed., and J. Lennox, "A Real- [RFC6465] Ivov, E., Ed., Marocco, E., Ed., and J. Lennox, "A Real-
time Transport Protocol (RTP) Header Extension for Mixer- time Transport Protocol (RTP) Header Extension for Mixer-
to-Client Audio Level Indication", RFC 6465, DOI 10.17487/ to-Client Audio Level Indication", RFC 6465,
RFC6465, December 2011, DOI 10.17487/RFC6465, December 2011, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc6465>. editor.org/info/rfc6465>.
Appendix A. Encryption Overview Appendix A. Encryption Overview
The following figure shows a double encrypted SRTP packet. The sides The following figure shows a double encrypted SRTP packet. The sides
indicate the parts of the packet that are encrypted and authenticated indicate the parts of the packet that are encrypted and authenticated
by the hob-by-hop and end-to-end operations. by the hob-by-hop and end-to-end operations.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<+<+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<+<+
 End of changes. 17 change blocks. 
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