draft-ietf-quic-tls-01.txt   draft-ietf-quic-tls-latest.txt 
QUIC Working Group M. Thomson, Ed. QUIC Working Group M. Thomson, Ed.
Internet-Draft Mozilla Internet-Draft Mozilla
Intended status: Standards Track S. Turner, Ed. Intended status: Standards Track S. Turner, Ed.
Expires: July 18, 2017 sn3rd Expires: August 27, 2017 sn3rd
January 14, 2017 February 23, 2017
Using Transport Layer Security (TLS) to Secure QUIC Using Transport Layer Security (TLS) to Secure QUIC
draft-ietf-quic-tls-01 draft-ietf-quic-tls-latest
Abstract Abstract
This document describes how Transport Layer Security (TLS) can be This document describes how Transport Layer Security (TLS) can be
used to secure QUIC. used to secure QUIC.
Note to Readers Note to Readers
Discussion of this draft takes place on the QUIC working group Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org), which is archived at mailing list (quic@ietf.org), which is archived at
skipping to change at page 2, line 30 skipping to change at page 2, line 30
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 July 18, 2017. This Internet-Draft will expire on August 27, 2017.
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
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 6 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 6
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7
3.1. TLS Overview . . . . . . . . . . . . . . . . . . . . . . . 8 3.1. TLS Overview . . . . . . . . . . . . . . . . . . . . . . . 8
3.2. TLS Handshake . . . . . . . . . . . . . . . . . . . . . . 8 3.2. TLS Handshake . . . . . . . . . . . . . . . . . . . . . . 8
4. TLS Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4. TLS Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1. Handshake and Setup Sequence . . . . . . . . . . . . . . . 10 4.1. Handshake and Setup Sequence . . . . . . . . . . . . . . . 10
4.2. Interface to TLS . . . . . . . . . . . . . . . . . . . . . 12 4.2. Interface to TLS . . . . . . . . . . . . . . . . . . . . . 12
4.2.1. Handshake Interface . . . . . . . . . . . . . . . . . 12 4.2.1. Handshake Interface . . . . . . . . . . . . . . . . . 12
4.2.2. Key Ready Events . . . . . . . . . . . . . . . . . . . 13 4.2.2. Source Address Validation . . . . . . . . . . . . . . 13
4.2.3. Secret Export . . . . . . . . . . . . . . . . . . . . 14 4.2.3. Key Ready Events . . . . . . . . . . . . . . . . . . . 14
4.2.4. TLS Interface Summary . . . . . . . . . . . . . . . . 14 4.2.4. Secret Export . . . . . . . . . . . . . . . . . . . . 15
5. QUIC Packet Protection . . . . . . . . . . . . . . . . . . . . 15 4.2.5. TLS Interface Summary . . . . . . . . . . . . . . . . 15
5.1. Installing New Keys . . . . . . . . . . . . . . . . . . . 15 4.3. TLS Version . . . . . . . . . . . . . . . . . . . . . . . 15
5.2. QUIC Key Expansion . . . . . . . . . . . . . . . . . . . . 15 4.4. Peer Authentication . . . . . . . . . . . . . . . . . . . 16
5.2.1. 0-RTT Secret . . . . . . . . . . . . . . . . . . . . . 15 5. QUIC Packet Protection . . . . . . . . . . . . . . . . . . . . 17
5.2.2. 1-RTT Secrets . . . . . . . . . . . . . . . . . . . . 16 5.1. Installing New Keys . . . . . . . . . . . . . . . . . . . 17
5.2.3. Packet Protection Key and IV . . . . . . . . . . . . . 17 5.2. QUIC Key Expansion . . . . . . . . . . . . . . . . . . . . 17
5.3. QUIC AEAD Usage . . . . . . . . . . . . . . . . . . . . . 18 5.2.1. 0-RTT Secret . . . . . . . . . . . . . . . . . . . . . 17
5.4. Packet Numbers . . . . . . . . . . . . . . . . . . . . . . 19 5.2.2. 1-RTT Secrets . . . . . . . . . . . . . . . . . . . . 18
6. Key Phases . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.2.3. Packet Protection Key and IV . . . . . . . . . . . . . 19
6.1. Packet Protection for the TLS Handshake . . . . . . . . . 20 5.3. QUIC AEAD Usage . . . . . . . . . . . . . . . . . . . . . 20
6.1.1. Initial Key Transitions . . . . . . . . . . . . . . . 21 5.4. Packet Numbers . . . . . . . . . . . . . . . . . . . . . . 21
6. Key Phases . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.1. Packet Protection for the TLS Handshake . . . . . . . . . 22
6.1.1. Initial Key Transitions . . . . . . . . . . . . . . . 23
6.1.2. Retransmission and Acknowledgment of Unprotected 6.1.2. Retransmission and Acknowledgment of Unprotected
Packets . . . . . . . . . . . . . . . . . . . . . . . 22 Packets . . . . . . . . . . . . . . . . . . . . . . . 24
6.2. Key Update . . . . . . . . . . . . . . . . . . . . . . . . 23 6.2. Key Update . . . . . . . . . . . . . . . . . . . . . . . . 25
7. Pre-handshake QUIC Messages . . . . . . . . . . . . . . . . . 25 7. Client Address Validation . . . . . . . . . . . . . . . . . . 27
7.1. Unprotected Packets Prior to Handshake Completion . . . . 26 7.1. HelloRetryRequest Address Validation . . . . . . . . . . . 27
7.1.1. STREAM Frames . . . . . . . . . . . . . . . . . . . . 26 7.2. NewSessionTicket Address Validation . . . . . . . . . . . 28
7.1.2. ACK Frames . . . . . . . . . . . . . . . . . . . . . . 26 7.3. Address Validation Token Integrity . . . . . . . . . . . . 28
7.1.3. WINDOW_UPDATE Frames . . . . . . . . . . . . . . . . . 27 8. Pre-handshake QUIC Messages . . . . . . . . . . . . . . . . . 29
7.1.4. Denial of Service with Unprotected Packets . . . . . . 27 8.1. Unprotected Packets Prior to Handshake Completion . . . . 30
7.2. Use of 0-RTT Keys . . . . . . . . . . . . . . . . . . . . 28 8.1.1. STREAM Frames . . . . . . . . . . . . . . . . . . . . 30
7.3. Protected Packets Prior to Handshake Completion . . . . . 28 8.1.2. ACK Frames . . . . . . . . . . . . . . . . . . . . . . 30
8. QUIC-Specific Additions to the TLS Handshake . . . . . . . . . 29 8.1.3. WINDOW_UPDATE Frames . . . . . . . . . . . . . . . . . 31
8.1. Protocol and Version Negotiation . . . . . . . . . . . . . 29 8.1.4. Denial of Service with Unprotected Packets . . . . . . 31
8.2. QUIC Extension . . . . . . . . . . . . . . . . . . . . . . 29 8.2. Use of 0-RTT Keys . . . . . . . . . . . . . . . . . . . . 32
8.3. Source Address Validation . . . . . . . . . . . . . . . . 30 8.3. Receiving Out-of-Order Protected Frames . . . . . . . . . 32
8.4. Priming 0-RTT . . . . . . . . . . . . . . . . . . . . . . 30 9. QUIC-Specific Additions to the TLS Handshake . . . . . . . . . 33
9. Security Considerations . . . . . . . . . . . . . . . . . . . 31 9.1. Protocol and Version Negotiation . . . . . . . . . . . . . 33
9.1. Packet Reflection Attack Mitigation . . . . . . . . . . . 31 9.2. QUIC Transport Parameters Extension . . . . . . . . . . . 33
9.2. Peer Denial of Service . . . . . . . . . . . . . . . . . . 31 9.3. Priming 0-RTT . . . . . . . . . . . . . . . . . . . . . . 34
10. Error codes . . . . . . . . . . . . . . . . . . . . . . . . . 33 10. Security Considerations . . . . . . . . . . . . . . . . . . . 35
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 10.1. Packet Reflection Attack Mitigation . . . . . . . . . . . 35
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36 10.2. Peer Denial of Service . . . . . . . . . . . . . . . . . . 35
12.1. Normative References . . . . . . . . . . . . . . . . . . . 36 11. Error codes . . . . . . . . . . . . . . . . . . . . . . . . . 37
12.2. Informative References . . . . . . . . . . . . . . . . . . 36 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 38 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 39 13.1. Normative References . . . . . . . . . . . . . . . . . . . 40
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 40 13.2. Informative References . . . . . . . . . . . . . . . . . . 40
C.1. Since draft-ietf-quic-tls-00: . . . . . . . . . . . . . . 40 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 42
C.2. Since draft-thomson-quic-tls-01: . . . . . . . . . . . . . 40 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 44
C.1. Since draft-ietf-quic-tls-00: . . . . . . . . . . . . . . 44
C.2. Since draft-thomson-quic-tls-01: . . . . . . . . . . . . . 44
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 45
1. Introduction 1. Introduction
QUIC [QUIC-TRANSPORT] provides a multiplexed transport. When used QUIC [QUIC-TRANSPORT] provides a multiplexed transport. When used
for HTTP [RFC7230] semantics [QUIC-HTTP] it provides several key for HTTP [RFC7230] semantics [QUIC-HTTP] it provides several key
advantages over HTTP/1.1 [RFC7230] or HTTP/2 [RFC7540] over TCP advantages over HTTP/1.1 [RFC7230] or HTTP/2 [RFC7540] over TCP
[RFC0793]. [RFC0793].
This document describes how QUIC can be secured using Transport Layer This document describes how QUIC can be secured using Transport Layer
Security (TLS) version 1.3 [I-D.ietf-tls-tls13]. TLS 1.3 provides Security (TLS) version 1.3 [I-D.ietf-tls-tls13]. TLS 1.3 provides
critical latency improvements for connection establishment over critical latency improvements for connection establishment over
previous versions. Absent packet loss, most new connections can be previous versions. Absent packet loss, most new connections can be
established and secured within a single round trip; on subsequent established and secured within a single round trip; on subsequent
connections between the same client and server, the client can often connections between the same client and server, the client can often
send application data immediately, that is, zero round trip setup. send application data immediately, that is, using a zero round trip
setup.
This document describes how the standardized TLS 1.3 can act a This document describes how the standardized TLS 1.3 can act a
security component of QUIC. The same design could work for TLS 1.2, security component of QUIC. The same design could work for TLS 1.2,
though few of the benefits QUIC provides would be realized due to the though few of the benefits QUIC provides would be realized due to the
handshake latency in versions of TLS prior to 1.3. handshake latency in versions of TLS prior to 1.3.
2. Notational Conventions 2. Notational Conventions
The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this
document. It's not shouting; when they are capitalized, they have document. It's not shouting; when they are capitalized, they have
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Rather than a strict layering, these two protocols are co-dependent: Rather than a strict layering, these two protocols are co-dependent:
QUIC uses the TLS handshake; TLS uses the reliability and ordered QUIC uses the TLS handshake; TLS uses the reliability and ordered
delivery provided by QUIC streams. delivery provided by QUIC streams.
This document defines how QUIC interacts with TLS. This includes a This document defines how QUIC interacts with TLS. This includes a
description of how TLS is used, how keying material is derived from description of how TLS is used, how keying material is derived from
TLS, and the application of that keying material to protect QUIC TLS, and the application of that keying material to protect QUIC
packets. Figure 1 shows the basic interactions between TLS and QUIC, packets. Figure 1 shows the basic interactions between TLS and QUIC,
with the QUIC packet protection being called out specially. with the QUIC packet protection being called out specially.
+------------+ +------------+ +------------+ +------------+
| |----- Handshake ---->| | | |------ Handshake ------>| |
| |<---- Handshake -----| | | |<-- Validate Address ---| |
| QUIC | | TLS | | |-- OK/Error/Validate -->| |
| |<----- 0-RTT OK -----| | | |<----- Handshake -------| |
| |<----- 1-RTT OK -----| | | QUIC |------ Validate ------->| TLS |
| |<-- Handshake Done --| | | | | |
+------------+ +------------+ | |<------ 0-RTT OK -------| |
| ^ ^ | | |<------ 1-RTT OK -------| |
| Protect | Protected | | | |<--- Handshake Done ----| |
v | Packet | | +------------+ +------------+
+------------+ / / | ^ ^ |
| QUIC | / / | Protect | Protected | |
| Packet |------ Get Secret ------' / v | Packet | |
| Protection |<------ Secret ----------' +------------+ / /
| QUIC | / /
| Packet |-------- Get Secret -------' /
| Protection |<-------- Secret -----------'
+------------+ +------------+
Figure 1: QUIC and TLS Interactions Figure 1: QUIC and TLS Interactions
The initial state of a QUIC connection has packets exchanged without The initial state of a QUIC connection has packets exchanged without
any form of protection. In this state, QUIC is limited to using any form of protection. In this state, QUIC is limited to using
stream 1 and associated packets. Stream 1 is reserved for a TLS stream 1 and associated packets. Stream 1 is reserved for a TLS
connection. This is a complete TLS connection as it would appear connection. This is a complete TLS connection as it would appear
when layered over TCP; the only difference is that QUIC provides the when layered over TCP; the only difference is that QUIC provides the
reliability and ordering that would otherwise be provided by TCP. reliability and ordering that would otherwise be provided by TCP.
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3.1. TLS Overview 3.1. TLS Overview
TLS provides two endpoints a way to establish a means of TLS provides two endpoints a way to establish a means of
communication over an untrusted medium (that is, the Internet) that communication over an untrusted medium (that is, the Internet) that
ensures that messages they exchange cannot be observed, modified, or ensures that messages they exchange cannot be observed, modified, or
forged. forged.
TLS features can be separated into two basic functions: an TLS features can be separated into two basic functions: an
authenticated key exchange and record protection. QUIC primarily authenticated key exchange and record protection. QUIC primarily
uses the authenticated key exchange provided by TLS; QUIC provides uses the authenticated key exchange provided by TLS but provides its
its own packet protection. own packet protection.
The TLS authenticated key exchange occurs between two entities: The TLS authenticated key exchange occurs between two entities:
client and server. The client initiates the exchange and the server client and server. The client initiates the exchange and the server
responds. If the key exchange completes successfully, both client responds. If the key exchange completes successfully, both client
and server will agree on a secret. TLS supports both pre-shared key and server will agree on a secret. TLS supports both pre-shared key
(PSK) and Diffie-Hellman (DH) key exchange. PSK is the basis for (PSK) and Diffie-Hellman (DH) key exchanges. PSK is the basis for
0-RTT; the latter provides perfect forward secrecy (PFS) when the DH 0-RTT; the latter provides perfect forward secrecy (PFS) when the DH
keys are destroyed. keys are destroyed.
After completing the TLS handshake, the client will have learned and After completing the TLS handshake, the client will have learned and
authenticated an identity for the server and the server is optionally authenticated an identity for the server and the server is optionally
able to learn and authenticate an identity for the client. TLS able to learn and authenticate an identity for the client. TLS
supports X.509 certificate-based authentication [RFC5280] for both supports X.509 certificate-based authentication [RFC5280] for both
server and client. server and client.
The TLS key exchange is resistent to tampering by attackers and it The TLS key exchange is resistent to tampering by attackers and it
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A simplified TLS 1.3 handshake with 0-RTT application data is shown A simplified TLS 1.3 handshake with 0-RTT application data is shown
in Figure 2, see [I-D.ietf-tls-tls13] for more options and details. in Figure 2, see [I-D.ietf-tls-tls13] for more options and details.
Client Server Client Server
ClientHello ClientHello
(0-RTT Application Data) --------> (0-RTT Application Data) -------->
ServerHello ServerHello
{EncryptedExtensions} {EncryptedExtensions}
{ServerConfiguration}
{Certificate}
{CertificateVerify}
{Finished} {Finished}
<-------- [Application Data] <-------- [Application Data]
(EndOfEarlyData) (EndOfEarlyData)
{Finished} --------> {Finished} -------->
[Application Data] <-------> [Application Data] [Application Data] <-------> [Application Data]
Figure 2: TLS Handshake with 0-RTT Figure 2: TLS Handshake with 0-RTT
This 0-RTT handshake is only possible if the client and server have This 0-RTT handshake is only possible if the client and server have
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of the handshake messages sent by the server. of the handshake messages sent by the server.
Two additional variations on this basic handshake exchange are Two additional variations on this basic handshake exchange are
relevant to this document: relevant to this document:
o The server can respond to a ClientHello with a HelloRetryRequest, o The server can respond to a ClientHello with a HelloRetryRequest,
which adds an additional round trip prior to the basic exchange. which adds an additional round trip prior to the basic exchange.
This is needed if the server wishes to request a different key This is needed if the server wishes to request a different key
exchange key from the client. HelloRetryRequest is also used to exchange key from the client. HelloRetryRequest is also used to
verify that the client is correctly able to receive packets on the verify that the client is correctly able to receive packets on the
address it claims to have (see Section 8.3). address it claims to have (see [QUIC-TRANSPORT]).
o A pre-shared key mode can be used for subsequent handshakes to o A pre-shared key mode can be used for subsequent handshakes to
avoid public key operations. This is the basis for 0-RTT data, avoid public key operations. This is the basis for 0-RTT data,
even if the remainder of the connection is protected by a new even if the remainder of the connection is protected by a new
Diffie-Hellman exchange. Diffie-Hellman exchange.
4. TLS Usage 4. TLS Usage
QUIC reserves stream 1 for a TLS connection. Stream 1 contains a QUIC reserves stream 1 for a TLS connection. Stream 1 contains a
complete TLS connection, which includes the TLS record layer. Other complete TLS connection, which includes the TLS record layer. Other
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The client transitions from cleartext (@C) to 0-RTT keys (@0) when The client transitions from cleartext (@C) to 0-RTT keys (@0) when
sending 0-RTT data, and subsequently to to 1-RTT keys (@1) for its sending 0-RTT data, and subsequently to to 1-RTT keys (@1) for its
second flight of TLS handshake messages. This creates the potential second flight of TLS handshake messages. This creates the potential
for unprotected packets to be received by a server in close proximity for unprotected packets to be received by a server in close proximity
to packets that are protected with 1-RTT keys. to packets that are protected with 1-RTT keys.
More information on key transitions is included in Section 6.1. More information on key transitions is included in Section 6.1.
4.2. Interface to TLS 4.2. Interface to TLS
As shown in Figure 1, the interface from QUIC to TLS consists of As shown in Figure 1, the interface from QUIC to TLS consists of four
three primary functions: Handshake, Key Ready Events, and Secret primary functions: Handshake, Source Address Validation, Key Ready
Export. Events, and Secret Export.
Additional functions might be needed to configure TLS. Additional functions might be needed to configure TLS.
4.2.1. Handshake Interface 4.2.1. Handshake Interface
In order to drive the handshake, TLS depends on being able to send In order to drive the handshake, TLS depends on being able to send
and receive handshake messages on stream 1. There are two basic and receive handshake messages on stream 1. There are two basic
functions on this interface: one where QUIC requests handshake functions on this interface: one where QUIC requests handshake
messages and one where QUIC provides handshake packets. messages and one where QUIC provides handshake packets.
Before starting the handshake QUIC provides TLS with the transport
parameters (see Section 9.2) that it wishes to carry.
A QUIC client starts TLS by requesting TLS handshake octets from TLS. A QUIC client starts TLS by requesting TLS handshake octets from TLS.
The client acquires handshake octets before sending its first packet. The client acquires handshake octets before sending its first packet.
A QUIC server starts the process by providing TLS with stream 1 A QUIC server starts the process by providing TLS with stream 1
octets. octets.
Each time that an endpoint receives data on stream 1, it delivers the Each time that an endpoint receives data on stream 1, it delivers the
octets to TLS if it is able. Each time that TLS is provided with new octets to TLS if it is able. Each time that TLS is provided with new
data, new handshake octets are requested from TLS. TLS might not data, new handshake octets are requested from TLS. TLS might not
provide any octets if the handshake messages it has received are provide any octets if the handshake messages it has received are
incomplete or it has no data to send. incomplete or it has no data to send.
Once the TLS handshake is complete, this is indicated to QUIC along Once the TLS handshake is complete, this is indicated to QUIC along
with any final handshake octets that TLS needs to send. Once the with any final handshake octets that TLS needs to send. TLS also
handshake is complete, TLS becomes passive. TLS can still receive provides QUIC with the transport parameters that the peer advertised
data from its peer and respond in kind that data, but it will not during the handshake.
need to send more data unless specifically requested - either by an
Once the handshake is complete, TLS becomes passive. TLS can still
receive data from its peer and respond in kind, but it will not need
to send more data unless specifically requested - either by an
application or QUIC. One reason to send data is that the server application or QUIC. One reason to send data is that the server
might wish to provide additional or updated session tickets to a might wish to provide additional or updated session tickets to a
client. client.
When the handshake is complete, QUIC only needs to provide TLS with When the handshake is complete, QUIC only needs to provide TLS with
any data that arrives on stream 1. In the same way that is done any data that arrives on stream 1. In the same way that is done
during the handshake, new data is requested from TLS after providing during the handshake, new data is requested from TLS after providing
received data. received data.
Important: Until the handshake is reported as complete, the Important: Until the handshake is reported as complete, the
connection and key exchange are not properly authenticated at the connection and key exchange are not properly authenticated at the
server. Even though 1-RTT keys are available to a server after server. Even though 1-RTT keys are available to a server after
receiving the first handshake messages from a client, the server receiving the first handshake messages from a client, the server
cannot consider the client to be authenticated until it receives cannot consider the client to be authenticated until it receives
and validates the client's Finished message. and validates the client's Finished message.
4.2.2. Key Ready Events The requirement for the server to wait for the client Finished
message creates a dependency on that message being delivered. A
client can avoid the potential for head-of-line blocking that this
implies by sending a copy of the STREAM frame that carries the
Finished message in multiple packets. This enables immediate
server processing for those packets.
4.2.2. Source Address Validation
During the processing of the TLS ClientHello, TLS requests that the
transport make a decision about whether to request source address
validation from the client.
An initial TLS ClientHello that resumes a session includes an address
validation token in the session ticket; this includes all attempts at
0-RTT. If the client does not attempt session resumption, no token
will be present. While processing the initial ClientHello, TLS
provides QUIC with any token that is present. In response, QUIC
provides one of three responses:
o proceed with the connection,
o ask for client address validation, or
o abort the connection.
If QUIC requests source address validation, it also provides a new
address validation token. TLS includes that along with any
information it requires in the cookie extension of a TLS
HelloRetryRequest message. In the other cases, the connection either
proceeds or terminates with a handshake error.
The client echoes the cookie extension in a second ClientHello. A
ClientHello that contains a valid cookie extension will be always be
in response to a HelloRetryRequest. If address validation was
requested by QUIC, then this will include an address validation
token. TLS makes a second address validation request of QUIC,
including the value extracted from the cookie extension. In response
to this request, QUIC cannot ask for client address validation, it
can only abort or permit the connection attempt to proceed.
QUIC can provide a new address validation token for use in session
resumption at any time after the handshake is complete. Each time a
new token is provided TLS generates a NewSessionTicket message, with
the token included in the ticket.
See Section 7 for more details on client address validation.
4.2.3. Key Ready Events
TLS provides QUIC with signals when 0-RTT and 1-RTT keys are ready TLS provides QUIC with signals when 0-RTT and 1-RTT keys are ready
for use. These events are not asynchronous, they always occur for use. These events are not asynchronous, they always occur
immediately after TLS is provided with new handshake octets, or after immediately after TLS is provided with new handshake octets, or after
TLS produces handshake octets. TLS produces handshake octets.
When TLS has enough information to generate 1-RTT keys, it indicates When TLS has enough information to generate 1-RTT keys, it indicates
their availability. On the client, this occurs after receiving the their availability. On the client, this occurs after receiving the
entirety of the first flight of TLS handshake messages from the entirety of the first flight of TLS handshake messages from the
server. A server indicates that 1-RTT keys are available after it server. A server indicates that 1-RTT keys are available after it
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ensures that the server sends its flight of handshake messages ensures that the server sends its flight of handshake messages
without protection. without protection.
If 0-RTT is possible, it is ready after the client sends a TLS If 0-RTT is possible, it is ready after the client sends a TLS
ClientHello message or the server receives that message. After ClientHello message or the server receives that message. After
providing a QUIC client with the first handshake octets, the TLS providing a QUIC client with the first handshake octets, the TLS
stack might signal that 0-RTT keys are ready. On the server, after stack might signal that 0-RTT keys are ready. On the server, after
receiving handshake octets that contain a ClientHello message, a TLS receiving handshake octets that contain a ClientHello message, a TLS
server might signal that 0-RTT keys are available. server might signal that 0-RTT keys are available.
1-RTT keys are used for both sending and receiving packets. 0-RTT 1-RTT keys are used for packets in both directions. 0-RTT keys are
keys are only used to protect packets that the client sends. only used to protect packets sent by the client.
4.2.3. Secret Export 4.2.4. Secret Export
Details how secrets are exported from TLS are included in Details how secrets are exported from TLS are included in
Section 5.2. Section 5.2.
4.2.4. TLS Interface Summary 4.2.5. TLS Interface Summary
Figure 4 summarizes the exchange between QUIC and TLS for both client Figure 4 summarizes the exchange between QUIC and TLS for both client
and server. and server.
Client Server Client Server
Get Handshake Get Handshake
0-RTT Key Ready 0-RTT Key Ready
--- send/receive ---> --- send/receive --->
Handshake Received Handshake Received
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--- send/receive ---> --- send/receive --->
Handshake Received Handshake Received
Get Handshake Get Handshake
Handshake Complete Handshake Complete
<--- send/receive --- <--- send/receive ---
Handshake Received Handshake Received
Get Handshake Get Handshake
Figure 4: Interaction Summary between QUIC and TLS Figure 4: Interaction Summary between QUIC and TLS
4.3. TLS Version
This document describes how TLS 1.3 [I-D.ietf-tls-tls13] is used with
QUIC.
In practice, the TLS handshake will negotiate a version of TLS to
use. This could result in a newer version of TLS than 1.3 being
negotiated if both endpoints support that version. This is
acceptable provided that the features of TLS 1.3 that are used by
QUIC are supported by the newer version.
A badly configured TLS implementation could negotiate TLS 1.2 or
another older version of TLS. An endpoint MUST terminate the
connection if a version of TLS older than 1.3 is negotiated.
4.4. Peer Authentication
The requirements for authentication depend on the application
protocol that is in use. TLS provides server authentication and
permits the server to request client authentication.
A client MUST authenticate the identity of the server. This
typically involves verification that the identity of the server is
included in a certificate and that the certificate is issued by a
trusted entity (see for example [RFC2818]).
A server MAY request that the client authenticate during the
handshake. A server MAY refuse a connection if the client is unable
to authenticate when requested. The requirements for client
authentication vary based on application protocol and deployment.
A server MUST NOT use post-handshake client authentication (see
Section 4.6.2 of [I-D.ietf-tls-tls13]).
5. QUIC Packet Protection 5. QUIC Packet Protection
QUIC packet protection provides authenticated encryption of packets. QUIC packet protection provides authenticated encryption of packets.
This provides confidentiality and integrity protection for the This provides confidentiality and integrity protection for the
content of packets (see Section 5.3). Packet protection uses keys content of packets (see Section 5.3). Packet protection uses keys
that are exported from the TLS connection (see Section 5.2). that are exported from the TLS connection (see Section 5.2).
Different keys are used for QUIC packet protection and TLS record Different keys are used for QUIC packet protection and TLS record
protection. Having separate QUIC and TLS record protection means protection. Having separate QUIC and TLS record protection means
that TLS records can be protected by two different keys. This that TLS records can be protected by two different keys. This
redundancy is limited to a only a few TLS records, and is maintained redundancy is limited to only a few TLS records, and is maintained
for the sake of simplicity. for the sake of simplicity.
5.1. Installing New Keys 5.1. Installing New Keys
As TLS reports the availability of keying material, the packet As TLS reports the availability of keying material, the packet
protection keys and initialization vectors (IVs) are updated (see protection keys and initialization vectors (IVs) are updated (see
Section 5.2). The selection of AEAD function is also updated to Section 5.2). The selection of AEAD function is also updated to
match the AEAD negotiated by TLS. match the AEAD negotiated by TLS.
For packets other than any unprotected handshake packets (see For packets other than any unprotected handshake packets (see
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This simplifies key management when there are key updates (see This simplifies key management when there are key updates (see
Section 6.2). Section 6.2).
5.2. QUIC Key Expansion 5.2. QUIC Key Expansion
QUIC uses a system of packet protection secrets, keys and IVs that QUIC uses a system of packet protection secrets, keys and IVs that
are modelled on the system used in TLS [I-D.ietf-tls-tls13]. The are modelled on the system used in TLS [I-D.ietf-tls-tls13]. The
secrets that QUIC uses as the basis of its key schedule are obtained secrets that QUIC uses as the basis of its key schedule are obtained
using TLS exporters (see Section 7.3.3 of [I-D.ietf-tls-tls13]). using TLS exporters (see Section 7.3.3 of [I-D.ietf-tls-tls13]).
QUIC uses the Pseudo-Random Function (PRF) hash function negotiated QUIC uses HKDF with the same hash function negotiated by TLS for key
by TLS for key derivation. For example, if TLS is using the derivation. For example, if TLS is using the TLS_AES_128_GCM_SHA256,
TLS_AES_128_GCM_SHA256, the SHA-256 hash function is used. the SHA-256 hash function is used.
5.2.1. 0-RTT Secret 5.2.1. 0-RTT Secret
0-RTT keys are those keys that are used in resumed connections prior 0-RTT keys are those keys that are used in resumed connections prior
to the completion of the TLS handshake. Data sent using 0-RTT keys to the completion of the TLS handshake. Data sent using 0-RTT keys
might be replayed and so has some restrictions on its use, see might be replayed and so has some restrictions on its use, see
Section 7.2. 0-RTT keys are used after sending or receiving a Section 8.2. 0-RTT keys are used after sending or receiving a
ClientHello. ClientHello.
The secret is exported from TLS using the exporter label "EXPORTER- The secret is exported from TLS using the exporter label "EXPORTER-
QUIC 0-RTT Secret" and an empty context. The size of the secret MUST QUIC 0-RTT Secret" and an empty context. The size of the secret MUST
be the size of the hash output for the PRF hash function negotiated be the size of the hash output for the PRF hash function negotiated
by TLS. This uses the TLS early_exporter_secret. The QUIC 0-RTT by TLS. This uses the TLS early_exporter_secret. The QUIC 0-RTT
secret is only used for protection of packets sent by the client. secret is only used for protection of packets sent by the client.
client_0rtt_secret client_0rtt_secret
= TLS-Exporter("EXPORTER-QUIC 0-RTT Secret" = TLS-Exporter("EXPORTER-QUIC 0-RTT Secret"
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"", Hash.length) "", Hash.length)
server_pp_secret_0 server_pp_secret_0
= TLS-Exporter("EXPORTER-QUIC server 1-RTT Secret" = TLS-Exporter("EXPORTER-QUIC server 1-RTT Secret"
"", Hash.length) "", Hash.length)
These secrets are used to derive the initial client and server packet These secrets are used to derive the initial client and server packet
protection keys. protection keys.
After a key update (see Section 6.2), these secrets are updated using After a key update (see Section 6.2), these secrets are updated using
the HKDF-Expand-Label function defined in Section 7.1 of the HKDF-Expand-Label function defined in Section 7.1 of
[I-D.ietf-tls-tls13]. HKDF-Expand-Label uses the the PRF hash [I-D.ietf-tls-tls13]. HKDF-Expand-Label uses the PRF hash function
function negotiated by TLS. The replacement secret is derived using negotiated by TLS. The replacement secret is derived using the
the existing Secret, a Label of "QUIC client 1-RTT Secret" for the existing Secret, a Label of "QUIC client 1-RTT Secret" for the client
client and "QUIC server 1-RTT Secret" for the server, an empty and "QUIC server 1-RTT Secret" for the server, an empty HashValue,
HashValue, and the same output Length as the hash function selected and the same output Length as the hash function selected by TLS for
by TLS for its PRF. its PRF.
client_pp_secret_<N+1> client_pp_secret_<N+1>
= HKDF-Expand-Label(client_pp_secret_<N>, = HKDF-Expand-Label(client_pp_secret_<N>,
"QUIC client 1-RTT Secret", "QUIC client 1-RTT Secret",
"", Hash.length) "", Hash.length)
server_pp_secret_<N+1> server_pp_secret_<N+1>
= HKDF-Expand-Label(server_pp_secret_<N>, = HKDF-Expand-Label(server_pp_secret_<N>,
"QUIC server 1-RTT Secret", "QUIC server 1-RTT Secret",
"", Hash.length) "", Hash.length)
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(client_pp_key_n) or the server packet protection key (client_pp_key_n) or the server packet protection key
(server_pp_key_n), derived as defined in Section 5.2. (server_pp_key_n), derived as defined in Section 5.2.
The nonce, N, for the AEAD is formed by combining either the packet The nonce, N, for the AEAD is formed by combining either the packet
protection IV (either client_pp_iv_n or server_pp_iv_n) with packet protection IV (either client_pp_iv_n or server_pp_iv_n) with packet
numbers. The 64 bits of the reconstructed QUIC packet number in numbers. The 64 bits of the reconstructed QUIC packet number in
network byte order is left-padded with zeros to the size of the IV. network byte order is left-padded with zeros to the size of the IV.
The exclusive OR of the padded packet number and the IV forms the The exclusive OR of the padded packet number and the IV forms the
AEAD nonce. AEAD nonce.
The associated data, A, for the AEAD is an empty sequence. The associated data, A, for the AEAD is the contents of the QUIC
header, starting from the flags octet in the common header.
The input plaintext, P, for the AEAD is the contents of the QUIC The input plaintext, P, for the AEAD is the contents of the QUIC
frame following the packet number, as described in [QUIC-TRANSPORT]. frame following the packet number, as described in [QUIC-TRANSPORT].
The output ciphertext, C, of the AEAD is transmitted in place of P. The output ciphertext, C, of the AEAD is transmitted in place of P.
Prior to TLS providing keys, no record protection is performed and Prior to TLS providing keys, no record protection is performed and
the plaintext, P, is transmitted unmodified. the plaintext, P, is transmitted unmodified.
5.4. Packet Numbers 5.4. Packet Numbers
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initial ClientHello. A HelloRetryRequest handshake message and any initial ClientHello. A HelloRetryRequest handshake message and any
second ClientHello that is sent in response MUST also be sent without second ClientHello that is sent in response MUST also be sent without
packet protection. This is natural, because no new keying material packet protection. This is natural, because no new keying material
will be available when these messages need to be sent. Upon receipt will be available when these messages need to be sent. Upon receipt
of a HelloRetryRequest, a client SHOULD cease any transmission of of a HelloRetryRequest, a client SHOULD cease any transmission of
0-RTT data; 0-RTT data will only be discarded by any server that 0-RTT data; 0-RTT data will only be discarded by any server that
sends a HelloRetryRequest. sends a HelloRetryRequest.
Note: TLS handshake data that needs to be sent without protection is Note: TLS handshake data that needs to be sent without protection is
all the handshake data acquired from TLS before the point that all the handshake data acquired from TLS before the point that
1-RTT keys are provided by TLS (see Section 4.2.2). 1-RTT keys are provided by TLS (see Section 4.2.3).
The KEY_PHASE and VERSION bits ensure that protected packets are The KEY_PHASE and VERSION bits ensure that protected packets are
clearly distinguished from unprotected packets. Loss or reordering clearly distinguished from unprotected packets. Loss or reordering
might cause unprotected packets to arrive once 1-RTT keys are in use, might cause unprotected packets to arrive once 1-RTT keys are in use,
unprotected packets are easily distinguished from 1-RTT packets. unprotected packets are easily distinguished from 1-RTT packets.
Once 1-RTT keys are available to an endpoint, it no longer needs the Once 1-RTT keys are available to an endpoint, it no longer needs the
TLS handshake messages that are carried in unprotected packets. TLS handshake messages that are carried in unprotected packets.
However, a server might need to retransmit its TLS handshake messages However, a server might need to retransmit its TLS handshake messages
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there are more than two different sets of keying material that might there are more than two different sets of keying material that might
be received by a peer. Once both sending and receiving keys have be received by a peer. Once both sending and receiving keys have
been updated, been updated,
A server cannot initiate a key update until it has received the A server cannot initiate a key update until it has received the
client's Finished message. Otherwise, packets protected by the client's Finished message. Otherwise, packets protected by the
updated keys could be confused for retransmissions of handshake updated keys could be confused for retransmissions of handshake
messages. A client cannot initiate a key update until all of its messages. A client cannot initiate a key update until all of its
handshake messages have been acknowledged by the server. handshake messages have been acknowledged by the server.
7. Pre-handshake QUIC Messages 7. Client Address Validation
Two tools are provided by TLS to enable validation of client source
addresses at a server: the cookie in the HelloRetryRequest message,
and the ticket in the NewSessionTicket message.
7.1. HelloRetryRequest Address Validation
The cookie extension in the TLS HelloRetryRequest message allows a
server to perform source address validation during the handshake.
When QUIC requests address validation during the processing of the
first ClientHello, the token it provides is included in the cookie
extension of a HelloRetryRequest. As long as the cookie cannot be
successfully guessed by a client, the server can be assured that the
client received the HelloRetryRequest if it includes the value in a
second ClientHello.
An initial ClientHello never includes a cookie extension. Thus, if a
server constructs a cookie that contains all the information
necessary to reconstruct state, it can discard local state after
sending a HelloRetryRequest. Presence of a valid cookie in a
ClientHello indicates that the ClientHello is a second attempt from
the client.
An address validation token can be extracted from a second
ClientHello and passed to the transport for further validation. If
that validation fails, the server MUST fail the TLS handshake and
send an illegal_parameter alert.
Combining address validation with the other uses of HelloRetryRequest
ensures that there are fewer ways in which an additional round-trip
can be added to the handshake. In particular, this makes it possible
to combine a request for address validation with a request for a
different client key share.
If TLS needs to send a HelloRetryRequest for other reasons, it needs
to ensure that it can correctly identify the reason that the
HelloRetryRequest was generated. During the processing of a second
ClientHello, TLS does not need to consult the transport protocol
regarding address validation if address validation was not requested
originally. In such cases, the cookie extension could either be
absent or it could indicate that an address validation token is not
present.
7.2. NewSessionTicket Address Validation
The ticket in the TLS NewSessionTicket message allows a server to
provide a client with a similar sort of token. When a client resumes
a TLS connection - whether or not 0-RTT is attempted - it includes
the ticket in the handshake message. As with the HelloRetryRequest
cookie, the server includes the address validation token in the
ticket. TLS provides the token it extracts from the session ticket
to the transport when it asks whether source address validation is
needed.
If both a HelloRetryRequest cookie and a session ticket are present
in the ClientHello, only the token from the cookie is passed to the
transport. The presence of a cookie indicates that this is a second
ClientHello - the token from the session ticket will have been
provided to the transport when it appeared in the first ClientHello.
A server can send a NewSessionTicket message at any time. This
allows it to update the state - and the address validation token -
that is included in the ticket. This might be done to refresh the
ticket or token, or it might be generated in response to changes in
the state of the connection. QUIC can request that a
NewSessionTicket be sent by providing a new address validation token.
A server that intends to support 0-RTT SHOULD provide an address
validation token immediately after completing the TLS handshake.
7.3. Address Validation Token Integrity
TLS MUST provide integrity protection for address validation token
unless the transport guarantees integrity protection by other means.
For a NewSessionTicket that includes confidential information - such
as the resumption secret - including the token under authenticated
encryption ensures that the token gains both confidentiality and
integrity protection without duplicating the overheads of that
protection.
8. Pre-handshake QUIC Messages
Implementations MUST NOT exchange data on any stream other than Implementations MUST NOT exchange data on any stream other than
stream 1 without packet protection. QUIC requires the use of several stream 1 without packet protection. QUIC requires the use of several
types of frame for managing loss detection and recovery during this types of frame for managing loss detection and recovery during this
phase. In addition, it might be useful to use the data acquired phase. In addition, it might be useful to use the data acquired
during the exchange of unauthenticated messages for congestion during the exchange of unauthenticated messages for congestion
control. control.
This section generally only applies to TLS handshake messages from This section generally only applies to TLS handshake messages from
both peers and acknowledgments of the packets carrying those both peers and acknowledgments of the packets carrying those
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if they can't be authenticated if they can't be authenticated
o save them and use them when they can be properly authenticated o save them and use them when they can be properly authenticated
o treat them as a fatal error o treat them as a fatal error
Different strategies are appropriate for different types of data. Different strategies are appropriate for different types of data.
This document proposes that all strategies are possible depending on This document proposes that all strategies are possible depending on
the type of message. the type of message.
o Transport parameters and options are made usable and authenticated o Transport parameters are made usable and authenticated as part of
as part of the TLS handshake (see Section 8.2). the TLS handshake (see Section 9.2).
o Most unprotected messages are treated as fatal errors when o Most unprotected messages are treated as fatal errors when
received except for the small number necessary to permit the received except for the small number necessary to permit the
handshake to complete (see Section 7.1). handshake to complete (see Section 8.1).
o Protected packets can either be discarded or saved and later used o Protected packets can either be discarded or saved and later used
(see Section 7.3). (see Section 8.3).
7.1. Unprotected Packets Prior to Handshake Completion 8.1. Unprotected Packets Prior to Handshake Completion
This section describes the handling of messages that are sent and This section describes the handling of messages that are sent and
received prior to the completion of the TLS handshake. received prior to the completion of the TLS handshake.
Sending and receiving unprotected messages is hazardous. Unless Sending and receiving unprotected messages is hazardous. Unless
expressly permitted, receipt of an unprotected message of any kind expressly permitted, receipt of an unprotected message of any kind
MUST be treated as a fatal error. MUST be treated as a fatal error.
7.1.1. STREAM Frames 8.1.1. STREAM Frames
"STREAM" frames for stream 1 are permitted. These carry the TLS "STREAM" frames for stream 1 are permitted. These carry the TLS
handshake messages. Once 1-RTT keys are available, unprotected handshake messages. Once 1-RTT keys are available, unprotected
"STREAM" frames on stream 1 can be ignored. "STREAM" frames on stream 1 can be ignored.
Receiving unprotected "STREAM" frames for other streams MUST be Receiving unprotected "STREAM" frames for other streams MUST be
treated as a fatal error. treated as a fatal error.
7.1.2. ACK Frames 8.1.2. ACK Frames
"ACK" frames are permitted prior to the handshake being complete. "ACK" frames are permitted prior to the handshake being complete.
Information learned from "ACK" frames cannot be entirely relied upon, Information learned from "ACK" frames cannot be entirely relied upon,
since an attacker is able to inject these packets. Timing and packet since an attacker is able to inject these packets. Timing and packet
retransmission information from "ACK" frames is critical to the retransmission information from "ACK" frames is critical to the
functioning of the protocol, but these frames might be spoofed or functioning of the protocol, but these frames might be spoofed or
altered. altered.
Endpoints MUST NOT use an unprotected "ACK" frame to acknowledge data Endpoints MUST NOT use an unprotected "ACK" frame to acknowledge data
that was protected by 0-RTT or 1-RTT keys. An endpoint MUST ignore that was protected by 0-RTT or 1-RTT keys. An endpoint MUST ignore
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problem if the handshake completes without loss, but it could mean problem if the handshake completes without loss, but it could mean
that 0-RTT stalls when a handshake packet disappears for any that 0-RTT stalls when a handshake packet disappears for any
reason. reason.
An endpoint SHOULD use data from unprotected or 0-RTT-protected "ACK" An endpoint SHOULD use data from unprotected or 0-RTT-protected "ACK"
frames only during the initial handshake and while they have frames only during the initial handshake and while they have
insufficient information from 1-RTT-protected "ACK" frames. Once insufficient information from 1-RTT-protected "ACK" frames. Once
sufficient information has been obtained from protected messages, sufficient information has been obtained from protected messages,
information obtained from less reliable sources can be discarded. information obtained from less reliable sources can be discarded.
7.1.3. WINDOW_UPDATE Frames 8.1.3. WINDOW_UPDATE Frames
"WINDOW_UPDATE" frames MUST NOT be sent unprotected. "WINDOW_UPDATE" frames MUST NOT be sent unprotected.
Though data is exchanged on stream 1, the initial flow control window Though data is exchanged on stream 1, the initial flow control window
is is sufficiently large to allow the TLS handshake to complete. is sufficiently large to allow the TLS handshake to complete. This
This limits the maximum size of the TLS handshake and would prevent a limits the maximum size of the TLS handshake and would prevent a
server or client from using an abnormally large certificate chain. server or client from using an abnormally large certificate chain.
Stream 1 is exempt from the connection-level flow control window. Stream 1 is exempt from the connection-level flow control window.
7.1.4. Denial of Service with Unprotected Packets 8.1.4. Denial of Service with Unprotected Packets
Accepting unprotected - specifically unauthenticated - packets Accepting unprotected - specifically unauthenticated - packets
presents a denial of service risk to endpoints. An attacker that is presents a denial of service risk to endpoints. An attacker that is
able to inject unprotected packets can cause a recipient to drop even able to inject unprotected packets can cause a recipient to drop even
protected packets with a matching sequence number. The spurious protected packets with a matching sequence number. The spurious
packet shadows the genuine packet, causing the genuine packet to be packet shadows the genuine packet, causing the genuine packet to be
ignored as redundant. ignored as redundant.
Once the TLS handshake is complete, both peers MUST ignore Once the TLS handshake is complete, both peers MUST ignore
unprotected packets. From that point onward, unprotected messages unprotected packets. From that point onward, unprotected messages
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ISSUE: This would not be an issue if QUIC had a randomized starting ISSUE: This would not be an issue if QUIC had a randomized starting
sequence number. If we choose to randomize, we fix this problem sequence number. If we choose to randomize, we fix this problem
and reduce the denial of service exposure to on-path attackers. and reduce the denial of service exposure to on-path attackers.
The only possible problem is in authenticating the initial value, The only possible problem is in authenticating the initial value,
so that peers can be sure that they haven't missed an initial so that peers can be sure that they haven't missed an initial
message. message.
In addition to causing valid packets to be dropped, an attacker can In addition to causing valid packets to be dropped, an attacker can
generate packets with an intent of causing the recipient to expend generate packets with an intent of causing the recipient to expend
processing resources. See Section 9.2 for a discussion of these processing resources. See Section 10.2 for a discussion of these
risks. risks.
To avoid receiving TLS packets that contain no useful data, a TLS To avoid receiving TLS packets that contain no useful data, a TLS
implementation MUST reject empty TLS handshake records and any record implementation MUST reject empty TLS handshake records and any record
that is not permitted by the TLS state machine. Any TLS application that is not permitted by the TLS state machine. Any TLS application
data or alerts that is received prior to the end of the handshake data or alerts that is received prior to the end of the handshake
MUST be treated as a fatal error. MUST be treated as a fatal error.
7.2. Use of 0-RTT Keys 8.2. Use of 0-RTT Keys
If 0-RTT keys are available, the lack of replay protection means that If 0-RTT keys are available, the lack of replay protection means that
restrictions on their use are necessary to avoid replay attacks on restrictions on their use are necessary to avoid replay attacks on
the protocol. the protocol.
A client MUST only use 0-RTT keys to protect data that is idempotent. A client MUST only use 0-RTT keys to protect data that is idempotent.
A client MAY wish to apply additional restrictions on what data it A client MAY wish to apply additional restrictions on what data it
sends prior to the completion of the TLS handshake. A client sends prior to the completion of the TLS handshake. A client
otherwise treats 0-RTT keys as equivalent to 1-RTT keys. otherwise treats 0-RTT keys as equivalent to 1-RTT keys.
A client that receives an indication that its 0-RTT data has been A client that receives an indication that its 0-RTT data has been
accepted by a server can send 0-RTT data until it receives all of the accepted by a server can send 0-RTT data until it receives all of the
server's handshake messages. A client SHOULD stop sending 0-RTT data server's handshake messages. A client SHOULD stop sending 0-RTT data
if it receives an indication that 0-RTT data has been rejected. if it receives an indication that 0-RTT data has been rejected.
A server MUST NOT use 0-RTT keys to protect packets. A server MUST NOT use 0-RTT keys to protect packets.
7.3. Protected Packets Prior to Handshake Completion 8.3. Receiving Out-of-Order Protected Frames
Due to reordering and loss, protected packets might be received by an Due to reordering and loss, protected packets might be received by an
endpoint before the final handshake messages are received. If these endpoint before the final TLS handshake messages are received. A
can be decrypted successfully, such packets MAY be stored and used client will be unable to decrypt 1-RTT packets from the server,
once the handshake is complete. whereas a server will be able to decrypt 1-RTT packets from the
client.
Unless expressly permitted below, encrypted packets MUST NOT be used
prior to completing the TLS handshake, in particular the receipt of a
valid Finished message and any authentication of the peer. If
packets are processed prior to completion of the handshake, an
attacker might use the willingness of an implementation to use these
packets to mount attacks.
TLS handshake messages are covered by record protection during the Packets protected with 1-RTT keys MAY be stored and later decrypted
handshake, once key agreement has completed. This means that and used once the handshake is complete. A server MUST NOT use 1-RTT
protected messages need to be decrypted to determine if they are TLS protected packets before verifying either the client Finished message
handshake messages or not. Similarly, "ACK" and "WINDOW_UPDATE" or - in the case that the server has chosen to use a pre-shared key -
frames might be needed to successfully complete the TLS handshake. the pre-shared key binder (see Section 4.2.8 of
[I-D.ietf-tls-tls13]). Verifying these values provides the server
with an assurance that the ClientHello has not been modified.
Any timestamps present in "ACK" frames MUST be ignored rather than A server could receive packets protected with 0-RTT keys prior to
causing a fatal error. Timestamps on protected frames MAY be saved receiving a TLS ClientHello. The server MAY retain these packets for
and used once the TLS handshake completes successfully. later decryption in anticipation of receiving a ClientHello.
An endpoint MAY save the last protected "WINDOW_UPDATE" frame it Receiving and verifying the TLS Finished message is critical in
receives for each stream and apply the values once the TLS handshake ensuring the integrity of the TLS handshake. A server MUST NOT use
completes. Failing to do this might result in temporary stalling of protected packets from the client prior to verifying the client
affected streams. Finished message if its response depends on client authentication.
8. QUIC-Specific Additions to the TLS Handshake 9. QUIC-Specific Additions to the TLS Handshake
QUIC uses the TLS handshake for more than just negotiation of QUIC uses the TLS handshake for more than just negotiation of
cryptographic parameters. The TLS handshake validates protocol cryptographic parameters. The TLS handshake validates protocol
version selection, provides preliminary values for QUIC transport version selection, provides preliminary values for QUIC transport
parameters, and allows a server to perform return routeability checks parameters, and allows a server to perform return routeability checks
on clients. on clients.
8.1. Protocol and Version Negotiation 9.1. Protocol and Version Negotiation
The QUIC version negotiation mechanism is used to negotiate the The QUIC version negotiation mechanism is used to negotiate the
version of QUIC that is used prior to the completion of the version of QUIC that is used prior to the completion of the
handshake. However, this packet is not authenticated, enabling an handshake. However, this packet is not authenticated, enabling an
active attacker to force a version downgrade. active attacker to force a version downgrade.
To ensure that a QUIC version downgrade is not forced by an attacker, To ensure that a QUIC version downgrade is not forced by an attacker,
version information is copied into the TLS handshake, which provides version information is copied into the TLS handshake, which provides
integrity protection for the QUIC negotiation. This does not prevent integrity protection for the QUIC negotiation. This does not prevent
version downgrade during the handshake, though it means that such a version downgrade during the handshake, though it means that such a
downgrade causes a handshake failure. downgrade causes a handshake failure.
Protocols that use the QUIC transport MUST use Application Layer TLS uses Application Layer Protocol Negotiation (ALPN) [RFC7301] to
Protocol Negotiation (ALPN) [RFC7301]. The ALPN identifier for the select an application protocol. The application-layer protocol MAY
protocol MUST be specific to the QUIC version that it operates over. restrict the QUIC versions that it can operate over. Servers MUST
When constructing a ClientHello, clients MUST include a list of all select an application protocol compatible with the QUIC version that
the ALPN identifiers that they support, regardless of whether the the client has selected.
QUIC version that they have currently selected supports that
protocol.
Servers SHOULD select an application protocol based solely on the
information in the ClientHello, not using the QUIC version that the
client has selected. If the protocol that is selected is not
supported with the QUIC version that is in use, the server MAY send a
QUIC version negotiation packet to select a compatible version.
If the server cannot select a combination of ALPN identifier and QUIC If the server cannot select a compatible combination of application
version it MUST abort the connection. A client MUST abort a protocol and QUIC version, it MUST abort the connection. A client
connection if the server picks an incompatible version of QUIC MUST abort a connection if the server picks an incompatible
version and ALPN. combination of QUIC version and ALPN identifier.
8.2. QUIC Extension 9.2. QUIC Transport Parameters Extension
QUIC defines an extension for use with TLS. That extension defines QUIC transport parameters are carried in a TLS extension. Different
transport-related parameters. This provides integrity protection for versions of QUIC might define a different format for this struct.
these values. Including these in the TLS handshake also make the
values that a client sets available to a server one-round trip
earlier than parameters that are carried in QUIC packets. This
document does not define that extension.
8.3. Source Address Validation Including transport parameters in the TLS handshake provides
integrity protection for these values.
QUIC implementations describe a source address token. This is an enum {
opaque blob that a server might provide to clients when they first quic_transport_parameters(26), (65535)
use a given source address. The client returns this token in } ExtensionType;
subsequent messages as a return routeability check. That is, the
client returns this token to prove that it is able to receive packets
at the source address that it claims. This prevents the server from
being used in packet reflection attacks (see Section 9.1).
A source address token is opaque and consumed only by the server. The "extension_data" field of the quic_transport_parameters extension
Therefore it can be included in the TLS 1.3 pre-shared key identifier contains a value that is defined by the version of QUIC that is in
for 0-RTT handshakes. Servers that use 0-RTT are advised to provide use. The quic_transport_parameters extension carries a
new pre-shared key identifiers after every handshake to avoid TransportParameters when the version of QUIC defined in
linkability of connections by passive observers. Clients MUST use a
new pre-shared key identifier for every connection that they
initiate; if no pre-shared key identifier is available, then
resumption is not possible.
A server that is under load might include a source address token in [QUIC-TRANSPORT] is used.
the cookie extension of a HelloRetryRequest.
8.4. Priming 0-RTT 9.3. Priming 0-RTT
QUIC uses TLS without modification. Therefore, it is possible to use QUIC uses TLS without modification. Therefore, it is possible to use
a pre-shared key that was obtained in a TLS connection over TCP to a pre-shared key that was obtained in a TLS connection over TCP to
enable 0-RTT in QUIC. Similarly, QUIC can provide a pre-shared key enable 0-RTT in QUIC. Similarly, QUIC can provide a pre-shared key
that can be used to enable 0-RTT in TCP. that can be used to enable 0-RTT in TCP.
All the restrictions on the use of 0-RTT apply, with the exception of All the restrictions on the use of 0-RTT apply, with the exception of
the ALPN label, which MUST only change to a label that is explicitly the ALPN label, which MUST only change to a label that is explicitly
designated as being compatible. The client indicates which ALPN designated as being compatible. The client indicates which ALPN
label it has chosen by placing that ALPN label first in the ALPN label it has chosen by placing that ALPN label first in the ALPN
skipping to change at page 31, line 5 skipping to change at page 35, line 5
Source address validation is not completely portable between Source address validation is not completely portable between
different protocol stacks. Even if the source IP address remains different protocol stacks. Even if the source IP address remains
constant, the port number is likely to be different. Packet constant, the port number is likely to be different. Packet
reflection attacks are still possible in this situation, though the reflection attacks are still possible in this situation, though the
set of hosts that can initiate these attacks is greatly reduced. A set of hosts that can initiate these attacks is greatly reduced. A
server might choose to avoid source address validation for such a server might choose to avoid source address validation for such a
connection, or allow an increase to the amount of data that it sends connection, or allow an increase to the amount of data that it sends
toward the client without source validation. toward the client without source validation.
9. Security Considerations 10. Security Considerations
There are likely to be some real clangers here eventually, but the There are likely to be some real clangers here eventually, but the
current set of issues is well captured in the relevant sections of current set of issues is well captured in the relevant sections of
the main text. the main text.
Never assume that because it isn't in the security considerations Never assume that because it isn't in the security considerations
section it doesn't affect security. Most of this document does. section it doesn't affect security. Most of this document does.
9.1. Packet Reflection Attack Mitigation 10.1. Packet Reflection Attack Mitigation
A small ClientHello that results in a large block of handshake A small ClientHello that results in a large block of handshake
messages from a server can be used in packet reflection attacks to messages from a server can be used in packet reflection attacks to
amplify the traffic generated by an attacker. amplify the traffic generated by an attacker.
Certificate caching [RFC7924] can reduce the size of the server's Certificate caching [RFC7924] can reduce the size of the server's
handshake messages significantly. handshake messages significantly.
A client SHOULD also pad [RFC7685] its ClientHello to at least 1024 A client SHOULD also pad [RFC7685] its ClientHello to at least 1024
octets. A server is less likely to generate a packet reflection octets. A server is less likely to generate a packet reflection
attack if the data it sends is a small multiple of the data it attack if the data it sends is a small multiple of the data it
receives. A server SHOULD use a HelloRetryRequest if the size of the receives. A server SHOULD use a HelloRetryRequest if the size of the
handshake messages it sends is likely to exceed the size of the handshake messages it sends is likely to exceed the size of the
ClientHello. ClientHello.
9.2. Peer Denial of Service 10.2. Peer Denial of Service
QUIC, TLS and HTTP/2 all contain a messages that have legitimate uses QUIC, TLS and HTTP/2 all contain a messages that have legitimate uses
in some contexts, but that can be abused to cause a peer to expend in some contexts, but that can be abused to cause a peer to expend
processing resources without having any observable impact on the processing resources without having any observable impact on the
state of the connection. If processing is disproportionately large state of the connection. If processing is disproportionately large
in comparison to the observable effects on bandwidth or state, then in comparison to the observable effects on bandwidth or state, then
this could allow a malicious peer to exhaust processing capacity this could allow a malicious peer to exhaust processing capacity
without consequence. without consequence.
QUIC prohibits the sending of empty "STREAM" frames unless they are QUIC prohibits the sending of empty "STREAM" frames unless they are
skipping to change at page 33, line 5 skipping to change at page 37, line 5
generate unnecessary work. Once the TLS handshake is complete, generate unnecessary work. Once the TLS handshake is complete,
endpoints SHOULD NOT send TLS application data records unless it is endpoints SHOULD NOT send TLS application data records unless it is
to hide the length of QUIC records. QUIC packet protection does not to hide the length of QUIC records. QUIC packet protection does not
include any allowance for padding; padded TLS application data include any allowance for padding; padded TLS application data
records can be used to mask the length of QUIC frames. records can be used to mask the length of QUIC frames.
While there are legitimate uses for some redundant packets, While there are legitimate uses for some redundant packets,
implementations SHOULD track redundant packets and treat excessive implementations SHOULD track redundant packets and treat excessive
volumes of any non-productive packets as indicative of an attack. volumes of any non-productive packets as indicative of an attack.
10. Error codes 11. Error codes
The portion of the QUIC error code space allocated for the crypto The portion of the QUIC error code space allocated for the crypto
handshake is 0xB000-0xFFFF. The following error codes are defined handshake is 0xC0000000-0xFFFFFFFF. The following error codes are
when TLS is used for the crypto handshake: defined when TLS is used for the crypto handshake:
TLS_HANDSHAKE_FAILED (0xB01c): Crypto errors. Handshake failed. TLS_HANDSHAKE_FAILED (0xC000001C): Crypto errors. Handshake failed.
TLS_MESSAGE_OUT_OF_ORDER (0xB01d): Handshake message received out of TLS_MESSAGE_OUT_OF_ORDER (0xC000001D): Handshake message received
order. out of order.
TLS_TOO_MANY_ENTRIES (0xB01e): Handshake message contained too many TLS_TOO_MANY_ENTRIES (0xC000001E): Handshake message contained too
entries. many entries.
TLS_INVALID_VALUE_LENGTH (0xB01f): Handshake message contained an TLS_INVALID_VALUE_LENGTH (0xC000001F): Handshake message contained
invalid value length. an invalid value length.
TLS_MESSAGE_AFTER_HANDSHAKE_COMPLETE (0xB020): A handshake message TLS_MESSAGE_AFTER_HANDSHAKE_COMPLETE (0xC0000020): A handshake
was received after the handshake was complete. message was received after the handshake was complete.
TLS_INVALID_RECORD_TYPE (0xB021): A handshake message was received TLS_INVALID_RECORD_TYPE (0xC0000021): A handshake message was
with an illegal record type. received with an illegal record type.
TLS_INVALID_PARAMETER (0xB022): A handshake message was received TLS_INVALID_PARAMETER (0xC0000022): A handshake message was received
with an illegal parameter. with an illegal parameter.
TLS_INVALID_CHANNEL_ID_SIGNATURE (0xB034): An invalid channel id TLS_INVALID_CHANNEL_ID_SIGNATURE (0xC0000034): An invalid channel id
signature was supplied. signature was supplied.
TLS_MESSAGE_PARAMETER_NOT_FOUND (0xB023): A handshake message was TLS_MESSAGE_PARAMETER_NOT_FOUND (0xC0000023): A handshake message
received with a mandatory parameter missing. was received with a mandatory parameter missing.
TLS_MESSAGE_PARAMETER_NO_OVERLAP (0xB024): A handshake message was TLS_MESSAGE_PARAMETER_NO_OVERLAP (0xC0000024): A handshake message
received with a parameter that has no overlap with the local was received with a parameter that has no overlap with the local
parameter. parameter.
TLS_MESSAGE_INDEX_NOT_FOUND (0xB025): A handshake message was TLS_MESSAGE_INDEX_NOT_FOUND (0xC0000025): A handshake message was
received that contained a parameter with too few values. received that contained a parameter with too few values.
TLS_UNSUPPORTED_PROOF_DEMAND (0xB05e): A demand for an unsupported TLS_UNSUPPORTED_PROOF_DEMAND (0xC000005E): A demand for an
proof type was received. unsupported proof type was received.
TLS_INTERNAL_ERROR (0xB026): An internal error occured in handshake TLS_INTERNAL_ERROR (0xC0000026): An internal error occured in
processing. handshake processing.
TLS_VERSION_NOT_SUPPORTED (0xB027): A handshake handshake message TLS_VERSION_NOT_SUPPORTED (0xC0000027): A handshake handshake
specified an unsupported version. message specified an unsupported version.
TLS_HANDSHAKE_STATELESS_REJECT (0xB048): A handshake handshake TLS_HANDSHAKE_STATELESS_REJECT (0xC0000048): A handshake handshake
message resulted in a stateless reject. message resulted in a stateless reject.
TLS_NO_SUPPORT (0xB028): There was no intersection between the TLS_NO_SUPPORT (0xC0000028): There was no intersection between the
crypto primitives supported by the peer and ourselves. crypto primitives supported by the peer and ourselves.
TLS_TOO_MANY_REJECTS (0xB029): The server rejected our client hello TLS_TOO_MANY_REJECTS (0xC0000029): The server rejected our client
messages too many times. hello messages too many times.
TLS_PROOF_INVALID (0xB02a): The client rejected the server's TLS_PROOF_INVALID (0xC000002A): The client rejected the server's
certificate chain or signature. certificate chain or signature.
TLS_DUPLICATE_TAG (0xB02b): A handshake message was received with a TLS_DUPLICATE_TAG (0xC000002B): A handshake message was received
duplicate tag. with a duplicate tag.
TLS_ENCRYPTION_LEVEL_INCORRECT (0xB02c): A handshake message was TLS_ENCRYPTION_LEVEL_INCORRECT (0xC000002C): A handshake message was
received with the wrong encryption level (i.e. it should have been received with the wrong encryption level (i.e. it should have been
encrypted but was not.) encrypted but was not.)
TLS_SERVER_CONFIG_EXPIRED (0xB02d): The server config for a server TLS_SERVER_CONFIG_EXPIRED (0xC000002D): The server config for a
has expired. server has expired.
TLS_SYMMETRIC_KEY_SETUP_FAILED (0xB035): We failed to set up the TLS_SYMMETRIC_KEY_SETUP_FAILED (0xC0000035): We failed to set up the
symmetric keys for a connection. symmetric keys for a connection.
TLS_MESSAGE_WHILE_VALIDATING_CLIENT_HELLO (0xB036): A handshake TLS_MESSAGE_WHILE_VALIDATING_CLIENT_HELLO (0xC0000036): A handshake
message arrived, but we are still validating the previous message arrived, but we are still validating the previous
handshake message. handshake message.
TLS_UPDATE_BEFORE_HANDSHAKE_COMPLETE (0xB041): A server config TLS_UPDATE_BEFORE_HANDSHAKE_COMPLETE (0xC0000041): A server config
update arrived before the handshake is complete. update arrived before the handshake is complete.
TLS_CLIENT_HELLO_TOO_LARGE (0xB05a): ClientHello cannot fit in one TLS_CLIENT_HELLO_TOO_LARGE (0xC000005A): ClientHello cannot fit in
packet. one packet.
11. IANA Considerations 12. IANA Considerations
This document has no IANA actions. Yet. This document has no IANA actions. Yet.
12. References 13. References
12.1. Normative References 13.1. Normative References
[I-D.ietf-tls-tls13] [I-D.ietf-tls-tls13]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", draft-ietf-tls-tls13-18 (work in progress), Version 1.3", draft-ietf-tls-tls13-18 (work in progress),
October 2016. October 2016.
[QUIC-TRANSPORT] [QUIC-TRANSPORT]
Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport". Multiplexed and Secure Transport".
skipping to change at page 36, line 46 skipping to change at page 40, line 46
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <http://www.rfc-editor.org/info/rfc7301>. July 2014, <http://www.rfc-editor.org/info/rfc7301>.
[RFC7685] Langley, A., "A Transport Layer Security (TLS) ClientHello [RFC7685] Langley, A., "A Transport Layer Security (TLS) ClientHello
Padding Extension", RFC 7685, DOI 10.17487/RFC7685, Padding Extension", RFC 7685, DOI 10.17487/RFC7685,
October 2015, <http://www.rfc-editor.org/info/rfc7685>. October 2015, <http://www.rfc-editor.org/info/rfc7685>.
12.2. Informative References 13.2. Informative References
[AEBounds] [AEBounds]
Luykx, A. and K. Paterson, "Limits on Authenticated Luykx, A. and K. Paterson, "Limits on Authenticated
Encryption Use in TLS", March 2016, Encryption Use in TLS", March 2016,
<http://www.isg.rhul.ac.uk/~kp/TLS-AEbounds.pdf>. <http://www.isg.rhul.ac.uk/~kp/TLS-AEbounds.pdf>.
[QUIC-HTTP] [QUIC-HTTP]
Bishop, M., Ed., "Hypertext Transfer Protocol (HTTP) over Bishop, M., Ed., "Hypertext Transfer Protocol (HTTP) over
QUIC". QUIC".
[QUIC-RECOVERY] [QUIC-RECOVERY]
Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection
and Congestion Control". and Congestion Control".
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>. <http://www.rfc-editor.org/info/rfc793>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/
RFC2818, May 2000,
<http://www.rfc-editor.org/info/rfc2818>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>. <http://www.rfc-editor.org/info/rfc5280>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>. <http://www.rfc-editor.org/info/rfc7540>.
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