Extended Key Update for QUIC
draft-ietf-quic-extended-key-update-01
| Document | Type | Active Internet-Draft (quic WG) | |
|---|---|---|---|
| Authors | Yaroslav Rosomakho , Hannes Tschofenig , Tirumaleswar Reddy.K | ||
| Last updated | 2025-07-07 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
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draft-ietf-quic-extended-key-update-01
QUIC Y. Rosomakho
Internet-Draft Zscaler
Updates: 9001 (if approved) H. Tschofenig
Intended status: Standards Track H-BRS
Expires: 8 January 2026 T. Reddy
Nokia
7 July 2025
Extended Key Update for QUIC
draft-ietf-quic-extended-key-update-01
Abstract
This document specifies an Extended Key Update mechanism for the QUIC
protocol, building on the foundation of the TLS Extended Key Update.
The TLS Extended Key Update specification enhances the TLS protocol
by introducing key updates with forward secrecy, eliminating the need
to perform a full handshake. This feature is particularly beneficial
for maintaining security in scenarios involving long-lived
connections.
This specification replaces the QUIC Key Update mechanism described
in the "Using TLS to Secure QUIC" specification.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at https://quicwg.org/
extended-key-update/draft-ietf-quic-extended-key-update.html. Status
information for this document may be found at
https://datatracker.ietf.org/doc/draft-ietf-quic-extended-key-
update/.
Discussion of this document takes place on the QUIC Working Group
mailing list (mailto:quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/quic/. Subscribe at
https://www.ietf.org/mailman/listinfo/quic/.
Source for this draft and an issue tracker can be found at
https://github.com/quicwg/extended-key-update.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 8 January 2026.
Copyright Notice
Copyright (c) 2025 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
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Extended Key Update Negotiation . . . . . . . . . . . . . . . 4
4. Extended Key Update Messages . . . . . . . . . . . . . . . . 4
5. Updating the Traffic Secrets . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The QUIC protocol [QUIC] provides a secure, versatile transport for
various applications, suitable for long-lived sessions in
environments like industrial IoT, telecommunication networks or
Virtual Private Networks (VPN), as specified in [RFC9484].
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The TLS Extended Key Update [I-D.ietf-tls-extended-key-update]
introduces a mechanism to enhance the security and flexibility of
encrypted communication protocols by enabling frequent key updates
without requiring a full handshake renegotiation. This approach
allows applications to refresh their encryption keys more often using
ephemeral keys, improving forward secrecy and reducing the risk of
key compromise over long-lived connections. By separating key
updates from the computationally expensive handshake process, the
specification provides a lightweight method for maintaining robust
encryption in scenarios where connections need to remain secure for
extended periods.
The TLS Extended Key Update mechanism is particularly valuable in
environments where interruptions to perform a full key exchange would
cause significant disruption. Other encrypted communication
protocols, such as IPsec [IKEv2] and SSH [SSH-TRANSPORT], include
mechanisms for rekeying without interrupting active sessions. The
TLS Extended Key Update specification helps protect sensitive data
even in the event of a potential key compromise by enabling frequent
key rotation and leveraging forward secrecy.
This specification builds on concepts from
[I-D.ietf-tls-extended-key-update] and applies them to the QUIC
protocol context. It thereby replaces the QUIC Key Update mechanism
described in Section 6 of [QUIC-TLS]. Unlike the previous QUIC key
update process, which independently updated keys based on the Key
Phase bit, the extended key update mechanism derives a new shared
secret using the TLS Extended Key Update procedure. This approach
enables a coordinated key transition, integrating TLS for key
exchange while refining the QUIC key update process to maintain QUIC-
specific key derivation.
2. Conventions and Definitions
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Readers are assumed to be familiar with
[I-D.ietf-tls-extended-key-update].
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3. Extended Key Update Negotiation
QUIC peers negotiate Extended Key Update through the TLS handshake
process, as outlined in Section 4 of
[I-D.ietf-tls-extended-key-update]. Extended Key Update MUST NOT be
used unless both QUIC peers include the TLS flags extension
[I-D.ietf-tls-tlsflags] in the handshake and set the
"Extended_Key_Update" flag.
Once the Extended Key Update has been successfully negotiated, QUIC
peers MUST use only the Extended Key Update process defined in this
document. The standard QUIC Key Update mechanism from Section 6 of
[QUIC-TLS] MUST NOT be used for the duration of the session, as both
Key Update and Extended Key Update use the Key Phase bit to signal
the use of updated keys. The Key Phase bit is initially set to 0 and
toggled to indicate a key update following the successful post-
handshake exchange of Extended Key Update messages.
4. Extended Key Update Messages
Either party MAY initiate the Extended Key Update process by sending
an ExtendedKeyUpdateRequest TLS handshake message in a QUIC CRYPTO
frame. This message MUST NOT be sent before the QUIC handshake is
confirmed, as described in Section 4.1.2 of [QUIC-TLS]. If a QUIC
endpoint receives an ExtendedKeyUpdateRequest message before the
handshake is complete, it MUST terminate the connection with an error
of type 0x010a, equivalent to the TLS unexpected_message alert, as
specified in Section 4.8 of [QUIC-TLS].
If both QUIC peers independently initiate an Extended Key Update and
their ExtendedKeyUpdateRequest messages cross in flight, the conflict
MUST be resolved following the clash error handling defined in
[I-D.ietf-tls-extended-key-update]. Specifically, the lexicographic
order of the key_exchange value in the KeyShareEntry determines which
request is rejected, ensuring a coordinated key update process
without advancing by two key generations.
Upon receiving an ExtendedKeyUpdateRequest, the recipient MUST
respond with an ExtendedKeyUpdateResponse TLS handshake message
within a QUIC CRYPTO frame. If a QUIC endpoint receives an
ExtendedKeyUpdateResponse without having previously sent an
ExtendedKeyUpdateRequest, it MUST treat this as a TLS protocol error
and terminate the connection with an error of type 0x010a, equivalent
to the TLS unexpected_message alert, as specified in Section 4.8 of
[QUIC-TLS].
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The ExtendedKeyUpdateRequest and ExtendedKeyUpdateResponse messages
are defined in Section 5 of [I-D.ietf-tls-extended-key-update]. Any
mismatch between the negotiated NamedGroup during the initial
handshake and the group used in the Extended Key Update message, or
an incorrect length of the encapsulated key MUST result in connection
termination with error of type 0x012f, equivalent to TLS
illegal_parameter alert.
If the Extended Key Update initiator receives a retry status in the
ExtendedKeyUpdateResponse message, it MUST wait for the duration
specified in the response before attempting another key update. The
ExtendedKeyUpdateResponse message contains a delay value (in seconds)
indicating how long the initiator MUST wait before retrying. The
initiator MUST NOT retry within this interval and SHOULD retry once
it has lapsed. If the initiator cannot proceed without an immediate
Extended Key Update, it MUST terminate the connection with an error
of type TBD1, equivalent to the TLS extended_key_update_required
alert.
If the initiator receives a rejected status, it MAY terminate the
connection with an error of type TBD1, equivalent to the TLS
extended_key_update_required alert.
5. Updating the Traffic Secrets
After sending an ExtendedKeyUpdateResponse with accepted status, the
responder derives new packet protection traffic secrets. The
responder MUST continue using the previous secrets until it has
received a packet with the Key Phase bit flipped and has successfully
decrypted it using the new keys.
After receiving and succesfully processing an
ExtendedKeyUpdateResponse with accepted status, the initiator derives
new packet protection traffic secrets, flips the Key Phase bit for
new packets, and uses the new write secret to protect them. The
initiator MUST retain the old read secret until it has received a
packet with a flipped Key Phase bit from the responder and
succesfully decrypted it using the new read secret.
Both endpoints SHOULD retain old read secrets for some time after
unprotecting a packet encrypted with the new keys. Discarding old
secret too early may cause delayed packets to be discarded, which the
peer may interpreted as packet loss, potentially impacting
performance.
Both endpoints SHOULD retain old read secrets for some time after
successfully decrypting a packet encrypted with the new keys.
Discarding old secrets too early may cause delayed packets to be
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discarded, which the peer may interpret as packet loss, potentially
impacting performance. However, implementations may choose to
discard old secrets sooner in environments where memory limitations
or security policies require minimizing the lifetime of old keys.
The retention period should be chosen carefully to mitigate the risk
of cryptographic attacks while still allowing late-arriving packets
to be processed.
Figure 1 shows this interaction graphically where the initial set of
keys used (identified with @M) are replaced by updated keys
(identified with @N). The value of the Key Phase bit is indicated in
brackets [].
Initiator Responder
@M [0] QUIC Packets
-------->
@M [0] QUIC Packets
<--------
[ ExtendedKeyUpdateRequest ] -------->
<-------- [ ExtendedKeyUpdateResponse ]
... Update to @N
@N [1] QUIC Packets
-------->
Update to @N ...
QUIC Packets [1] @N
<--------
QUIC Packets [1] @N
containing ACK
<--------
... Key Update Permitted
@N [1] QUIC Packets
containing ACK for @N packets
-------->
Key Update Permitted ...
Figure 1: Extended Key Update Process in QUIC.
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QUIC endpoints MUST NOT send NewKeyUpdate TLS handshake messages,
defined in [I-D.ietf-tls-extended-key-update], and instead rely on
the use of the Key Phase bit. Endpoints MUST treat the receipt of a
TLS NewKeyUpdate message as a connection error of type 0x010a. QUIC
endpoints that have agreed to the Extended Key Update process MUST
NOT change the Key Phase bit without a succesful exchange of Extended
Key Update TLS messages. Receiving a packet with the Key Phase bit
changed without a success Extended Key Update exchange MUST be
treated as a connection error of type KEY_UPDATE_ERROR (0x0e).
Key derivation function for computing the next generation of secrets
is described in Section 6 of [I-D.ietf-tls-extended-key-update]. The
corresponding key and IV are derived from the new secret as defined
in Section 5.1 of [QUIC-TLS]. The header protection key is not
updated.
6. Security Considerations
This specification describes an update to the key schedule of QUIC.
Therefore, implementations MUST ensure that peers adhere strictly to
the process described in this document. Packets with higher packet
numbers MUST NOT be protected using an older generation of secrets,
as this could compromise key synchronization and forward security.
As key exchange may be computationally intensive, responders SHOULD
consider rate-limiting Extended Key Exchange requests. This can be
done by responding with retry status as outlined in Section 5 of
[I-D.ietf-tls-extended-key-update] and terminating connections for
initiators that violate the back-off timer. This approach helps
prevent excessive load on endpoints and mitigates the risk of denial-
of-service attacks.
7. IANA Considerations
This document has no IANA actions.
8. References
8.1. Normative References
[I-D.ietf-tls-extended-key-update]
Tschofenig, H., Tüxen, M., Reddy.K, T., Fries, S., and Y.
Rosomakho, "Extended Key Update for Transport Layer
Security (TLS) 1.3", Work in Progress, Internet-Draft,
draft-ietf-tls-extended-key-update-04, 3 March 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-tls-
extended-key-update-04>.
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[I-D.ietf-tls-tlsflags]
Nir, Y., "A Flags Extension for TLS 1.3", Work in
Progress, Internet-Draft, draft-ietf-tls-tlsflags-15, 15
March 2025, <https://datatracker.ietf.org/doc/html/draft-
ietf-tls-tlsflags-15>.
[QUIC] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/rfc/rfc9000>.
[QUIC-TLS] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure
QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021,
<https://www.rfc-editor.org/rfc/rfc9001>.
[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/rfc/rfc2119>.
[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/rfc/rfc8174>.
8.2. Informative References
[IKEv2] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/rfc/rfc7296>.
[RFC9484] Pauly, T., Ed., Schinazi, D., Chernyakhovsky, A.,
Kühlewind, M., and M. Westerlund, "Proxying IP in HTTP",
RFC 9484, DOI 10.17487/RFC9484, October 2023,
<https://www.rfc-editor.org/rfc/rfc9484>.
[SSH-TRANSPORT]
Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
January 2006, <https://www.rfc-editor.org/rfc/rfc4253>.
Acknowledgments
We would like to thank Martin Thomson and Sean Turner for their early
review of this design and their invaluable feedback.
Authors' Addresses
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Yaroslav Rosomakho
Zscaler
Email: yrosomakho@zscaler.com
Hannes Tschofenig
University of Applied Sciences Bonn-Rhein-Sieg
Germany
Email: Hannes.Tschofenig@gmx.net
Tirumaleswar Reddy
Nokia
Bangalore
Karnataka
India
Email: kondtir@gmail.com
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