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QUIC M. Thomson, Ed.
Internet-Draft Mozilla
Intended status: Standards Track S. Turner, Ed.
Expires: July 18, 2017 sn3rd
January 14, 2017
Using Transport Layer Security (TLS) to Secure QUIC
draft-ietf-quic-tls-01
Abstract
This document describes how Transport Layer Security (TLS) can be
used to secure QUIC.
Note to Readers
Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/search/?email_list=quic .
Working Group information can be found at https://github.com/quicwg ;
source code and issues list for this draft can be found at
https://github.com/quicwg/base-drafts/labels/tls .
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 18, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4
3.1. TLS Overview . . . . . . . . . . . . . . . . . . . . . . 5
3.2. TLS Handshake . . . . . . . . . . . . . . . . . . . . . . 6
4. TLS Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Handshake and Setup Sequence . . . . . . . . . . . . . . 7
4.2. Interface to TLS . . . . . . . . . . . . . . . . . . . . 9
4.2.1. Handshake Interface . . . . . . . . . . . . . . . . . 9
4.2.2. Key Ready Events . . . . . . . . . . . . . . . . . . 10
4.2.3. Secret Export . . . . . . . . . . . . . . . . . . . . 11
4.2.4. TLS Interface Summary . . . . . . . . . . . . . . . . 11
5. QUIC Packet Protection . . . . . . . . . . . . . . . . . . . 11
5.1. Installing New Keys . . . . . . . . . . . . . . . . . . . 12
5.2. QUIC Key Expansion . . . . . . . . . . . . . . . . . . . 12
5.2.1. 0-RTT Secret . . . . . . . . . . . . . . . . . . . . 12
5.2.2. 1-RTT Secrets . . . . . . . . . . . . . . . . . . . . 13
5.2.3. Packet Protection Key and IV . . . . . . . . . . . . 14
5.3. QUIC AEAD Usage . . . . . . . . . . . . . . . . . . . . . 15
5.4. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 15
6. Key Phases . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Packet Protection for the TLS Handshake . . . . . . . . . 17
6.1.1. Initial Key Transitions . . . . . . . . . . . . . . . 17
6.1.2. Retransmission and Acknowledgment of Unprotected
Packets . . . . . . . . . . . . . . . . . . . . . . . 18
6.2. Key Update . . . . . . . . . . . . . . . . . . . . . . . 19
7. Pre-handshake QUIC Messages . . . . . . . . . . . . . . . . . 21
7.1. Unprotected Packets Prior to Handshake Completion . . . . 22
7.1.1. STREAM Frames . . . . . . . . . . . . . . . . . . . . 22
7.1.2. ACK Frames . . . . . . . . . . . . . . . . . . . . . 22
7.1.3. WINDOW_UPDATE Frames . . . . . . . . . . . . . . . . 23
7.1.4. Denial of Service with Unprotected Packets . . . . . 23
7.2. Use of 0-RTT Keys . . . . . . . . . . . . . . . . . . . . 24
7.3. Protected Packets Prior to Handshake Completion . . . . . 24
8. QUIC-Specific Additions to the TLS Handshake . . . . . . . . 25
8.1. Protocol and Version Negotiation . . . . . . . . . . . . 25
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8.2. QUIC Extension . . . . . . . . . . . . . . . . . . . . . 26
8.3. Source Address Validation . . . . . . . . . . . . . . . . 26
8.4. Priming 0-RTT . . . . . . . . . . . . . . . . . . . . . . 26
9. Security Considerations . . . . . . . . . . . . . . . . . . . 27
9.1. Packet Reflection Attack Mitigation . . . . . . . . . . . 27
9.2. Peer Denial of Service . . . . . . . . . . . . . . . . . 27
10. Error codes . . . . . . . . . . . . . . . . . . . . . . . . . 28
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
12.1. Normative References . . . . . . . . . . . . . . . . . . 30
12.2. Informative References . . . . . . . . . . . . . . . . . 31
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 31
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 31
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 32
C.1. Since draft-ietf-quic-tls-00: . . . . . . . . . . . . . . 32
C.2. Since draft-thomson-quic-tls-01: . . . . . . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
1. Introduction
QUIC [QUIC-TRANSPORT] provides a multiplexed transport. When used
for HTTP [RFC7230] semantics [QUIC-HTTP] it provides several key
advantages over HTTP/1.1 [RFC7230] or HTTP/2 [RFC7540] over TCP
[RFC0793].
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
critical latency improvements for connection establishment over
previous versions. Absent packet loss, most new connections can be
established and secured within a single round trip; on subsequent
connections between the same client and server, the client can often
send application data immediately, that is, zero round trip setup.
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,
though few of the benefits QUIC provides would be realized due to the
handshake latency in versions of TLS prior to 1.3.
2. Notational Conventions
The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this
document. It's not shouting; when they are capitalized, they have
the special meaning defined in [RFC2119].
This document uses the terminology established in [QUIC-TRANSPORT].
For brevity, the acronym TLS is used to refer to TLS 1.3.
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TLS terminology is used when referring to parts of TLS. Though TLS
assumes a continuous stream of octets, it divides that stream into
_records_. Most relevant to QUIC are the records that contain TLS
_handshake messages_, which are discrete messages that are used for
key agreement, authentication and parameter negotiation. Ordinarily,
TLS records can also contain _application data_, though in the QUIC
usage there is no use of TLS application data.
3. Protocol Overview
QUIC [QUIC-TRANSPORT] assumes responsibility for the confidentiality
and integrity protection of packets. For this it uses keys derived
from a TLS 1.3 connection [I-D.ietf-tls-tls13]; QUIC also relies on
TLS 1.3 for authentication and negotiation of parameters that are
critical to security and performance.
Rather than a strict layering, these two protocols are co-dependent:
QUIC uses the TLS handshake; TLS uses the reliability and ordered
delivery provided by QUIC streams.
This document defines how QUIC interacts with TLS. This includes a
description of how TLS is used, how keying material is derived from
TLS, and the application of that keying material to protect QUIC
packets. Figure 1 shows the basic interactions between TLS and QUIC,
with the QUIC packet protection being called out specially.
+------------+ +------------+
| |----- Handshake ---->| |
| |<---- Handshake -----| |
| QUIC | | TLS |
| |<----- 0-RTT OK -----| |
| |<----- 1-RTT OK -----| |
| |<-- Handshake Done --| |
+------------+ +------------+
| ^ ^ |
| Protect | Protected | |
v | Packet | |
+------------+ / /
| QUIC | / /
| Packet |------ Get Secret ------' /
| Protection |<------ Secret ----------'
+------------+
Figure 1: QUIC and TLS Interactions
The initial state of a QUIC connection has packets exchanged without
any form of protection. In this state, QUIC is limited to using
stream 1 and associated packets. Stream 1 is reserved for a TLS
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connection. This is a complete TLS connection as it would appear
when layered over TCP; the only difference is that QUIC provides the
reliability and ordering that would otherwise be provided by TCP.
At certain points during the TLS handshake, keying material is
exported from the TLS connection for use by QUIC. This keying
material is used to derive packet protection keys. Details on how
and when keys are derived and used are included in Section 5.
This arrangement means that some TLS messages receive redundant
protection from both the QUIC packet protection and the TLS record
protection. These messages are limited in number; the TLS connection
is rarely needed once the handshake completes.
3.1. TLS Overview
TLS provides two endpoints a way to establish a means of
communication over an untrusted medium (that is, the Internet) that
ensures that messages they exchange cannot be observed, modified, or
forged.
TLS features can be separated into two basic functions: an
authenticated key exchange and record protection. QUIC primarily
uses the authenticated key exchange provided by TLS; QUIC provides
its own packet protection.
The TLS authenticated key exchange occurs between two entities:
client and server. The client initiates the exchange and the server
responds. If the key exchange completes successfully, both client
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
0-RTT; the latter provides perfect forward secrecy (PFS) when the DH
keys are destroyed.
After completing the TLS handshake, the client will have learned and
authenticated an identity for the server and the server is optionally
able to learn and authenticate an identity for the client. TLS
supports X.509 certificate-based authentication [RFC5280] for both
server and client.
The TLS key exchange is resistent to tampering by attackers and it
produces shared secrets that cannot be controlled by either
participating peer.
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3.2. TLS Handshake
TLS 1.3 provides two basic handshake modes of interest to QUIC:
o A full, 1-RTT handshake in which the client is able to send
application data after one round trip and the server immediately
after receiving the first handshake message from the client.
o A 0-RTT handshake in which the client uses information it has
previously learned about the server to send immediately. This
data can be replayed by an attacker so it MUST NOT carry a self-
contained trigger for any non-idempotent action.
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.
Client Server
ClientHello
(0-RTT Application Data) -------->
ServerHello
{EncryptedExtensions}
{ServerConfiguration}
{Certificate}
{CertificateVerify}
{Finished}
<-------- [Application Data]
(EndOfEarlyData)
{Finished} -------->
[Application Data] <-------> [Application Data]
Figure 2: TLS Handshake with 0-RTT
This 0-RTT handshake is only possible if the client and server have
previously communicated. In the 1-RTT handshake, the client is
unable to send protected application data until it has received all
of the handshake messages sent by the server.
Two additional variations on this basic handshake exchange are
relevant to this document:
o The server can respond to a ClientHello with a HelloRetryRequest,
which adds an additional round trip prior to the basic exchange.
This is needed if the server wishes to request a different key
exchange key from the client. HelloRetryRequest is also used to
verify that the client is correctly able to receive packets on the
address it claims to have (see Section 8.3).
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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,
even if the remainder of the connection is protected by a new
Diffie-Hellman exchange.
4. TLS Usage
QUIC reserves stream 1 for a TLS connection. Stream 1 contains a
complete TLS connection, which includes the TLS record layer. Other
than the definition of a QUIC-specific extension (see Section-TBD),
TLS is unmodified for this use. This means that TLS will apply
confidentiality and integrity protection to its records. In
particular, TLS record protection is what provides confidentiality
protection for the TLS handshake messages sent by the server.
QUIC permits a client to send frames on streams starting from the
first packet. The initial packet from a client contains a stream
frame for stream 1 that contains the first TLS handshake messages
from the client. This allows the TLS handshake to start with the
first packet that a client sends.
QUIC packets are protected using a scheme that is specific to QUIC,
see Section 5. Keys are exported from the TLS connection when they
become available using a TLS exporter (see Section 7.3.3 of
[I-D.ietf-tls-tls13] and Section 5.2). After keys are exported from
TLS, QUIC manages its own key schedule.
4.1. Handshake and Setup Sequence
The integration of QUIC with a TLS handshake is shown in more detail
in Figure 3. QUIC "STREAM" frames on stream 1 carry the TLS
handshake. QUIC performs loss recovery [QUIC-RECOVERY] for this
stream and ensures that TLS handshake messages are delivered in the
correct order.
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Client Server
@C QUIC STREAM Frame(s) <1>:
ClientHello
+ QUIC Extension
-------->
0-RTT Key => @0
@0 QUIC STREAM Frame(s) <any stream>:
Replayable QUIC Frames
-------->
QUIC STREAM Frame <1>: @C
ServerHello
{TLS Handshake Messages}
<--------
1-RTT Key => @1
QUIC Frames <any> @1
<--------
@1 QUIC STREAM Frame(s) <1>:
(EndOfEarlyData)
{Finished}
-------->
@1 QUIC Frames <any> <-------> QUIC Frames <any> @1
Figure 3: QUIC over TLS Handshake
In Figure 3, symbols mean:
o "<" and ">" enclose stream numbers.
o "@" indicates the key phase that is currently used for protecting
QUIC packets.
o "(" and ")" enclose messages that are protected with TLS 0-RTT
handshake or application keys.
o "{" and "}" enclose messages that are protected by the TLS
Handshake keys.
If 0-RTT is not attempted, then the client does not send packets
protected by the 0-RTT key (@0). In that case, the only key
transition on the client is from unprotected packets (@C) to 1-RTT
protection (@1), which happens before it sends its final set of TLS
handshake messages.
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The server sends TLS handshake messages without protection (@C). The
server transitions from no protection (@C) to full 1-RTT protection
(@1) after it sends the last of its handshake messages.
Some TLS handshake messages are protected by the TLS handshake record
protection. These keys are not exported from the TLS connection for
use in QUIC. QUIC packets from the server are sent in the clear
until the final transition to 1-RTT keys.
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
second flight of TLS handshake messages. This creates the potential
for unprotected packets to be received by a server in close proximity
to packets that are protected with 1-RTT keys.
More information on key transitions is included in Section 6.1.
4.2. Interface to TLS
As shown in Figure 1, the interface from QUIC to TLS consists of
three primary functions: Handshake, Key Ready Events, and Secret
Export.
Additional functions might be needed to configure TLS.
4.2.1. Handshake Interface
In order to drive the handshake, TLS depends on being able to send
and receive handshake messages on stream 1. There are two basic
functions on this interface: one where QUIC requests handshake
messages and one where QUIC provides handshake packets.
A QUIC client starts TLS by requesting TLS handshake octets from TLS.
The client acquires handshake octets before sending its first packet.
A QUIC server starts the process by providing TLS with stream 1
octets.
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
data, new handshake octets are requested from TLS. TLS might not
provide any octets if the handshake messages it has received are
incomplete or it has no data to send.
Once the TLS handshake is complete, this is indicated to QUIC along
with any final handshake octets that TLS needs to send. Once the
handshake is complete, TLS becomes passive. TLS can still receive
data from its peer and respond in kind that data, but it will not
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need to send more data unless specifically requested - either by an
application or QUIC. One reason to send data is that the server
might wish to provide additional or updated session tickets to a
client.
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
during the handshake, new data is requested from TLS after providing
received data.
Important: Until the handshake is reported as complete, the
connection and key exchange are not properly authenticated at the
server. Even though 1-RTT keys are available to a server after
receiving the first handshake messages from a client, the server
cannot consider the client to be authenticated until it receives
and validates the client's Finished message.
4.2.2. Key Ready Events
TLS provides QUIC with signals when 0-RTT and 1-RTT keys are ready
for use. These events are not asynchronous, they always occur
immediately after TLS is provided with new handshake octets, or after
TLS produces handshake octets.
When TLS has enough information to generate 1-RTT keys, it indicates
their availability. On the client, this occurs after receiving the
entirety of the first flight of TLS handshake messages from the
server. A server indicates that 1-RTT keys are available after it
sends its handshake messages.
This ordering ensures that a client sends its second flight of
handshake messages protected with 1-RTT keys. More importantly, it
ensures that the server sends its flight of handshake messages
without protection.
If 0-RTT is possible, it is ready after the client sends a TLS
ClientHello message or the server receives that message. After
providing a QUIC client with the first handshake octets, the TLS
stack might signal that 0-RTT keys are ready. On the server, after
receiving handshake octets that contain a ClientHello message, a TLS
server might signal that 0-RTT keys are available.
1-RTT keys are used for both sending and receiving packets. 0-RTT
keys are only used to protect packets that the client sends.
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4.2.3. Secret Export
Details how secrets are exported from TLS are included in
Section 5.2.
4.2.4. TLS Interface Summary
Figure 4 summarizes the exchange between QUIC and TLS for both client
and server.
Client Server
Get Handshake
0-RTT Key Ready
--- send/receive --->
Handshake Received
0-RTT Key Ready
Get Handshake
1-RTT Keys Ready
<--- send/receive ---
Handshake Received
1-RTT Keys Ready
Get Handshake
Handshake Complete
--- send/receive --->
Handshake Received
Get Handshake
Handshake Complete
<--- send/receive ---
Handshake Received
Get Handshake
Figure 4: Interaction Summary between QUIC and TLS
5. QUIC Packet Protection
QUIC packet protection provides authenticated encryption of packets.
This provides confidentiality and integrity protection for the
content of packets (see Section 5.3). Packet protection uses keys
that are exported from the TLS connection (see Section 5.2).
Different keys are used for QUIC packet protection and TLS record
protection. Having separate QUIC and TLS record protection means
that TLS records can be protected by two different keys. This
redundancy is limited to a only a few TLS records, and is maintained
for the sake of simplicity.
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5.1. Installing New Keys
As TLS reports the availability of keying material, the packet
protection keys and initialization vectors (IVs) are updated (see
Section 5.2). The selection of AEAD function is also updated to
match the AEAD negotiated by TLS.
For packets other than any unprotected handshake packets (see
Section 6.1), once a change of keys has been made, packets with
higher packet numbers MUST use the new keying material. The
KEY_PHASE bit on these packets is inverted each time new keys are
installed to signal the use of the new keys to the recipient (see
Section 6 for details).
An endpoint retransmits stream data in a new packet. New packets
have new packet numbers and use the latest packet protection keys.
This simplifies key management when there are key updates (see
Section 6.2).
5.2. QUIC Key Expansion
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
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]).
QUIC uses the Pseudo-Random Function (PRF) hash function negotiated
by TLS for key derivation. For example, if TLS is using the
TLS_AES_128_GCM_SHA256, the SHA-256 hash function is used.
5.2.1. 0-RTT Secret
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
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
ClientHello.
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
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
secret is only used for protection of packets sent by the client.
client_0rtt_secret
= TLS-Exporter("EXPORTER-QUIC 0-RTT Secret"
"", Hash.length)
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5.2.2. 1-RTT Secrets
1-RTT keys are used by both client and server after the TLS handshake
completes. There are two secrets used at any time: one is used to
derive packet protection keys for packets sent by the client, the
other for protecting packets sent by the server.
The initial client packet protection secret is exported from TLS
using the exporter label "EXPORTER-QUIC client 1-RTT Secret"; the
initial server packet protection secret uses the exporter label
"EXPORTER-QUIC server 1-RTT Secret". Both exporters use an empty
context. The size of the secret MUST be the size of the hash output
for the PRF hash function negotiated by TLS.
client_pp_secret_0
= TLS-Exporter("EXPORTER-QUIC client 1-RTT Secret"
"", Hash.length)
server_pp_secret_0
= TLS-Exporter("EXPORTER-QUIC server 1-RTT Secret"
"", Hash.length)
These secrets are used to derive the initial client and server packet
protection keys.
After a key update (see Section 6.2), these secrets are updated using
the HKDF-Expand-Label function defined in Section 7.1 of
[I-D.ietf-tls-tls13]. HKDF-Expand-Label uses the the PRF hash
function negotiated by TLS. The replacement secret is derived using
the existing Secret, a Label of "QUIC client 1-RTT Secret" for the
client and "QUIC server 1-RTT Secret" for the server, an empty
HashValue, and the same output Length as the hash function selected
by TLS for its PRF.
client_pp_secret_<N+1>
= HKDF-Expand-Label(client_pp_secret_<N>,
"QUIC client 1-RTT Secret",
"", Hash.length)
server_pp_secret_<N+1>
= HKDF-Expand-Label(server_pp_secret_<N>,
"QUIC server 1-RTT Secret",
"", Hash.length)
This allows for a succession of new secrets to be created as needed.
HKDF-Expand-Label uses HKDF-Expand [RFC5869] with a specially
formatted info parameter. The info parameter that includes the
output length (in this case, the size of the PRF hash output) encoded
on two octets in network byte order, the length of the prefixed Label
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as a single octet, the value of the Label prefixed with "TLS 1.3, ",
and a zero octet to indicate an empty HashValue. For example, the
client packet protection secret uses an info parameter of:
info = (HashLen / 256) || (HashLen % 256) || 0x21 ||
"TLS 1.3, QUIC client 1-RTT secret" || 0x00
5.2.3. Packet Protection Key and IV
The complete key expansion uses an identical process for key
expansion as defined in Section 7.3 of [I-D.ietf-tls-tls13], using
different values for the input secret. QUIC uses the AEAD function
negotiated by TLS.
The packet protection key and IV used to protect the 0-RTT packets
sent by a client use the QUIC 0-RTT secret. This uses the HKDF-
Expand-Label with the PRF hash function negotiated by TLS.
The length of the output is determined by the requirements of the
AEAD function selected by TLS. The key length is the AEAD key size.
As defined in Section 5.3 of [I-D.ietf-tls-tls13], the IV length is
the larger of 8 or N_MIN (see Section 4 of [RFC5116]).
client_0rtt_key = HKDF-Expand-Label(client_0rtt_secret,
"key", "", key_length)
client_0rtt_iv = HKDF-Expand-Label(client_0rtt_secret,
"iv", "", iv_length)
Similarly, the packet protection key and IV used to protect 1-RTT
packets sent by both client and server use the current packet
protection secret.
client_pp_key_<N> = HKDF-Expand-Label(client_pp_secret_<N>,
"key", "", key_length)
client_pp_iv_<N> = HKDF-Expand-Label(client_pp_secret_<N>,
"iv", "", iv_length)
server_pp_key_<N> = HKDF-Expand-Label(server_pp_secret_<N>,
"key", "", key_length)
server_pp_iv_<N> = HKDF-Expand-Label(server_pp_secret_<N>,
"iv", "", iv_length)
The client protects (or encrypts) packets with the client packet
protection key and IV; the server protects packets with the server
packet protection key.
The QUIC record protection initially starts without keying material.
When the TLS state machine reports that the ClientHello has been
sent, the 0-RTT keys can be generated and installed for writing.
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When the TLS state machine reports completion of the handshake, the
1-RTT keys can be generated and installed for writing.
5.3. QUIC AEAD Usage
The Authentication Encryption with Associated Data (AEAD) [RFC5116]
function used for QUIC packet protection is AEAD that is negotiated
for use with the TLS connection. For example, if TLS is using the
TLS_AES_128_GCM_SHA256, the AEAD_AES_128_GCM function is used.
Regular QUIC packets are protected by an AEAD [RFC5116]. Version
negotiation and public reset packets are not protected.
Once TLS has provided a key, the contents of regular QUIC packets
immediately after any TLS messages have been sent are protected by
the AEAD selected by TLS.
The key, K, for the AEAD is either the client packet protection key
(client_pp_key_n) or the server packet protection key
(server_pp_key_n), derived as defined in Section 5.2.
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
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.
The exclusive OR of the padded packet number and the IV forms the
AEAD nonce.
The associated data, A, for the AEAD is an empty sequence.
The input plaintext, P, for the AEAD is the contents of the QUIC
frame following the packet number, as described in [QUIC-TRANSPORT].
The output ciphertext, C, of the AEAD is transmitted in place of P.
Prior to TLS providing keys, no record protection is performed and
the plaintext, P, is transmitted unmodified.
5.4. Packet Numbers
QUIC has a single, contiguous packet number space. In comparison,
TLS restarts its sequence number each time that record protection
keys are changed. The sequence number restart in TLS ensures that a
compromise of the current traffic keys does not allow an attacker to
truncate the data that is sent after a key update by sending
additional packets under the old key (causing new packets to be
discarded).
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QUIC does not assume a reliable transport and is required to handle
attacks where packets are dropped in other ways. QUIC is therefore
not affected by this form of truncation.
The packet number is not reset and it is not permitted to go higher
than its maximum value of 2^64-1. This establishes a hard limit on
the number of packets that can be sent.
Some AEAD functions have limits for how many packets can be encrypted
under the same key and IV (see for example [AEBounds]). This might
be lower than the packet number limit. An endpoint MUST initiate a
key update (Section 6.2) prior to exceeding any limit set for the
AEAD that is in use.
TLS maintains a separate sequence number that is used for record
protection on the connection that is hosted on stream 1. This
sequence number is not visible to QUIC.
6. Key Phases
As TLS reports the availability of 0-RTT and 1-RTT keys, new keying
material can be exported from TLS and used for QUIC packet
protection. At each transition during the handshake a new secret is
exported from TLS and packet protection keys are derived from that
secret.
Every time that a new set of keys is used for protecting outbound
packets, the KEY_PHASE bit in the public flags is toggled. The
exception is the transition from 0-RTT keys to 1-RTT keys, where the
presence of the version field and its associated bit is used (see
Section 6.1.1).
Once the connection is fully enabled, the KEY_PHASE bit allows a
recipient to detect a change in keying material without necessarily
needing to receive the first packet that triggered the change. An
endpoint that notices a changed KEY_PHASE bit can update keys and
decrypt the packet that contains the changed bit, see Section 6.2.
The KEY_PHASE bit is the third bit of the public flags (0x04).
Transitions between keys during the handshake are complicated by the
need to ensure that TLS handshake messages are sent with the correct
packet protection.
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6.1. Packet Protection for the TLS Handshake
The initial exchange of packets are sent without protection. These
packets are marked with a KEY_PHASE of 0.
TLS handshake messages that are critical to the TLS key exchange
cannot be protected using QUIC packet protection. A KEY_PHASE of 0
is used for all of these packets, even during retransmission. The
messages critical to key exchange are the TLS ClientHello and any TLS
handshake message from the server, except those that are sent after
the handshake completes, such as NewSessionTicket.
The second flight of TLS handshake messages from the client, and any
TLS handshake messages that are sent after completing the TLS
handshake do not need special packet protection rules. This includes
the EndOfEarlyData message that is sent by a client to mark the end
of its 0-RTT data. Packets containing these messages use the packet
protection keys that are current at the time of sending (or
retransmission).
Like the client, a server MUST send retransmissions of its
unprotected handshake messages or acknowledgments for unprotected
handshake messages sent by the client in unprotected packets
(KEY_PHASE=0).
6.1.1. Initial Key Transitions
Once the TLS key exchange is complete, keying material is exported
from TLS and QUIC packet protection commences.
Packets protected with 1-RTT keys have a KEY_PHASE bit set to 1.
These packets also have a VERSION bit set to 0.
If the client is unable to send 0-RTT data - or it does not have
0-RTT data to send - packet protection with 1-RTT keys starts with
the packets that contain its second flight of TLS handshake messages.
That is, the flight containing the TLS Finished handshake message and
optionally a Certificate and CertificateVerify message.
If the client sends 0-RTT data, it marks packets protected with 0-RTT
keys with a KEY_PHASE of 1 and a VERSION bit of 1. Setting the
version bit means that all packets also include the version field.
The client removes the VERSION bit when it transitions to using 1-RTT
keys, but it does not change the KEY_PHASE bit.
Marking 0-RTT data with the both KEY_PHASE and VERSION bits ensures
that the server is able to identify these packets as 0-RTT data in
case the packet containing the TLS ClientHello is lost or delayed.
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Including the version also ensures that the packet format is known to
the server in this case.
Using both KEY_PHASE and VERSION also ensures that the server is able
to distinguish between cleartext handshake packets (KEY_PHASE=0,
VERSION=1), 0-RTT protected packets (KEY_PHASE=1, VERSION=1), and
1-RTT protected packets (KEY_PHASE=1, VERSION=0). Packets with all
of these markings can arrive concurrently, and being able to identify
each cleanly ensures that the correct packet protection keys can be
selected and applied.
A server might choose to retain 0-RTT packets that arrive before a
TLS ClientHello. The server can then use those packets once the
ClientHello arrives. However, the potential for denial of service
from buffering 0-RTT packets is significant. These packets cannot be
authenticated and so might be employed by an attacker to exhaust
server resources. Limiting the number of packets that are saved
might be necessary.
The server transitions to using 1-RTT keys after sending its first
flight of TLS handshake messages. From this point, the server
protects all packets with 1-RTT keys. Future packets are therefore
protected with 1-RTT keys and marked with a KEY_PHASE of 1.
6.1.2. Retransmission and Acknowledgment of Unprotected Packets
The first flight of TLS handshake messages from both client and
server (ClientHello, or ServerHello through to the server's Finished)
are critical to the key exchange. The contents of these messages
determines the keys used to protect later messages. If these
handshake messages are included in packets that are protected with
these keys, they will be indecipherable to the recipient.
Even though newer keys could be available when retranmitting,
retransmissions of these handshake messages MUST be sent in
unprotected packets (with a KEY_PHASE of 0). An endpoint MUST also
generate ACK frames for these messages that are sent in unprotected
packets.
The TLS handshake messages that are affected by this rule are
specifically:
o A client MUST NOT restransmit a TLS ClientHello with 0-RTT keys.
The server needs this message in order to determine the 0-RTT
keys.
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o A server MUST NOT retransmit any of its TLS handshake messages
with 1-RTT keys. The client needs these messages in order to
determine the 1-RTT keys.
A HelloRetryRequest handshake message might be used to reject an
initial ClientHello. A HelloRetryRequest handshake message and any
second ClientHello that is sent in response MUST also be sent without
packet protection. This is natural, because no new keying material
will be available when these messages need to be sent. Upon receipt
of a HelloRetryRequest, a client SHOULD cease any transmission of
0-RTT data; 0-RTT data will only be discarded by any server that
sends a HelloRetryRequest.
Note: TLS handshake data that needs to be sent without protection is
all the handshake data acquired from TLS before the point that
1-RTT keys are provided by TLS (see Section 4.2.2).
The KEY_PHASE and VERSION bits ensure that protected packets are
clearly distinguished from unprotected packets. Loss or reordering
might cause unprotected packets to arrive once 1-RTT keys are in use,
unprotected packets are easily distinguished from 1-RTT packets.
Once 1-RTT keys are available to an endpoint, it no longer needs the
TLS handshake messages that are carried in unprotected packets.
However, a server might need to retransmit its TLS handshake messages
in response to receiving an unprotected packet that contains ACK
frames. A server MUST process ACK frames in unprotected packets
until the TLS handshake is reported as complete, or it receives an
ACK frame in a protected packet that acknowledges all of its
handshake messages.
To limit the number of key phases that could be active, an endpoint
MUST NOT initiate a key update while there are any unacknowledged
handshake messages, see Section 6.2.
6.2. Key Update
Once the TLS handshake is complete, the KEY_PHASE bit allows for
refreshes of keying material by either peer. Endpoints start using
updated keys immediately without additional signaling; the change in
the KEY_PHASE bit indicates that a new key is in use.
An endpoint MUST NOT initiate more than one key update at a time. A
new key cannot be used until the endpoint has received and
successfully decrypted a packet with a matching KEY_PHASE. Note that
when 0-RTT is attempted the value of the KEY_PHASE bit will be
different on packets sent by either peer.
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A receiving endpoint detects an update when the KEY_PHASE bit doesn't
match what it is expecting. It creates a new secret (see
Section 5.2) and the corresponding read key and IV. If the packet
can be decrypted and authenticated using these values, then the keys
it uses for packet protection are also updated. The next packet sent
by the endpoint will then use the new keys.
An endpoint doesn't need to send packets immediately when it detects
that its peer has updated keys. The next packet that it sends will
simply use the new keys. If an endpoint detects a second update
before it has sent any packets with updated keys it indicates that
its peer has updated keys twice without awaiting a reciprocal update.
An endpoint MUST treat consecutive key updates as a fatal error and
abort the connection.
An endpoint SHOULD retain old keys for a short period to allow it to
decrypt packets with smaller packet numbers than the packet that
triggered the key update. This allows an endpoint to consume packets
that are reordered around the transition between keys. Packets with
higher packet numbers always use the updated keys and MUST NOT be
decrypted with old keys.
Keys and their corresponding secrets SHOULD be discarded when an
endpoint has received all packets with sequence numbers lower than
the lowest sequence number used for the new key. An endpoint might
discard keys if it determines that the length of the delay to
affected packets is excessive.
This ensures that once the handshake is complete, packets with the
same KEY_PHASE will have the same packet protection keys, unless
there are multiple key updates in a short time frame succession and
significant packet reordering.
Initiating Peer Responding Peer
@M QUIC Frames
New Keys -> @N
@N QUIC Frames
-------->
QUIC Frames @M
New Keys -> @N
QUIC Frames @N
<--------
Figure 5: Key Update
As shown in Figure 3 and Figure 5, there is never a situation where
there are more than two different sets of keying material that might
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be received by a peer. Once both sending and receiving keys have
been updated,
A server cannot initiate a key update until it has received the
client's Finished message. Otherwise, packets protected by the
updated keys could be confused for retransmissions of handshake
messages. A client cannot initiate a key update until all of its
handshake messages have been acknowledged by the server.
7. Pre-handshake QUIC Messages
Implementations MUST NOT exchange data on any stream other than
stream 1 without packet protection. QUIC requires the use of several
types of frame for managing loss detection and recovery during this
phase. In addition, it might be useful to use the data acquired
during the exchange of unauthenticated messages for congestion
control.
This section generally only applies to TLS handshake messages from
both peers and acknowledgments of the packets carrying those
messages. In many cases, the need for servers to provide
acknowledgments is minimal, since the messages that clients send are
small and implicitly acknowledged by the server's responses.
The actions that a peer takes as a result of receiving an
unauthenticated packet needs to be limited. In particular, state
established by these packets cannot be retained once record
protection commences.
There are several approaches possible for dealing with
unauthenticated packets prior to handshake completion:
o discard and ignore them
o use them, but reset any state that is established once the
handshake completes
o use them and authenticate them afterwards; failing the handshake
if they can't be authenticated
o save them and use them when they can be properly authenticated
o treat them as a fatal error
Different strategies are appropriate for different types of data.
This document proposes that all strategies are possible depending on
the type of message.
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o Transport parameters and options are made usable and authenticated
as part of the TLS handshake (see Section 8.2).
o Most unprotected messages are treated as fatal errors when
received except for the small number necessary to permit the
handshake to complete (see Section 7.1).
o Protected packets can either be discarded or saved and later used
(see Section 7.3).
7.1. Unprotected Packets Prior to Handshake Completion
This section describes the handling of messages that are sent and
received prior to the completion of the TLS handshake.
Sending and receiving unprotected messages is hazardous. Unless
expressly permitted, receipt of an unprotected message of any kind
MUST be treated as a fatal error.
7.1.1. STREAM Frames
"STREAM" frames for stream 1 are permitted. These carry the TLS
handshake messages. Once 1-RTT keys are available, unprotected
"STREAM" frames on stream 1 can be ignored.
Receiving unprotected "STREAM" frames for other streams MUST be
treated as a fatal error.
7.1.2. ACK Frames
"ACK" frames are permitted prior to the handshake being complete.
Information learned from "ACK" frames cannot be entirely relied upon,
since an attacker is able to inject these packets. Timing and packet
retransmission information from "ACK" frames is critical to the
functioning of the protocol, but these frames might be spoofed or
altered.
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
an unprotected "ACK" frame if it claims to acknowledge data that was
sent in a protected packet. Such an acknowledgement can only serve
as a denial of service, since an endpoint that can read protected
data is always able to send protected data.
ISSUE: What about 0-RTT data? Should we allow acknowledgment of
0-RTT with unprotected frames? If we don't, then 0-RTT data will
be unacknowledged until the handshake completes. This isn't a
problem if the handshake completes without loss, but it could mean
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that 0-RTT stalls when a handshake packet disappears for any
reason.
An endpoint SHOULD use data from unprotected or 0-RTT-protected "ACK"
frames only during the initial handshake and while they have
insufficient information from 1-RTT-protected "ACK" frames. Once
sufficient information has been obtained from protected messages,
information obtained from less reliable sources can be discarded.
7.1.3. WINDOW_UPDATE Frames
"WINDOW_UPDATE" frames MUST NOT be sent unprotected.
Though data is exchanged on stream 1, the initial flow control window
is is sufficiently large to allow the TLS handshake to complete.
This limits the maximum size of the TLS handshake and would prevent a
server or client from using an abnormally large certificate chain.
Stream 1 is exempt from the connection-level flow control window.
7.1.4. Denial of Service with Unprotected Packets
Accepting unprotected - specifically unauthenticated - packets
presents a denial of service risk to endpoints. An attacker that is
able to inject unprotected packets can cause a recipient to drop even
protected packets with a matching sequence number. The spurious
packet shadows the genuine packet, causing the genuine packet to be
ignored as redundant.
Once the TLS handshake is complete, both peers MUST ignore
unprotected packets. From that point onward, unprotected messages
can be safely dropped.
Since only TLS handshake packets and acknowledgments are sent in the
clear, an attacker is able to force implementations to rely on
retransmission for packets that are lost or shadowed. Thus, an
attacker that intends to deny service to an endpoint has to drop or
shadow protected packets in order to ensure that their victim
continues to accept unprotected packets. The ability to shadow
packets means that an attacker does not need to be on path.
ISSUE: This would not be an issue if QUIC had a randomized starting
sequence number. If we choose to randomize, we fix this problem
and reduce the denial of service exposure to on-path attackers.
The only possible problem is in authenticating the initial value,
so that peers can be sure that they haven't missed an initial
message.
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In addition to causing valid packets to be dropped, an attacker can
generate packets with an intent of causing the recipient to expend
processing resources. See Section 9.2 for a discussion of these
risks.
To avoid receiving TLS packets that contain no useful data, a TLS
implementation MUST reject empty TLS handshake records and any record
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
MUST be treated as a fatal error.
7.2. Use of 0-RTT Keys
If 0-RTT keys are available, the lack of replay protection means that
restrictions on their use are necessary to avoid replay attacks on
the protocol.
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
sends prior to the completion of the TLS handshake. A client
otherwise treats 0-RTT keys as equivalent to 1-RTT keys.
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
server's handshake messages. A client SHOULD stop sending 0-RTT data
if it receives an indication that 0-RTT data has been rejected.
A server MUST NOT use 0-RTT keys to protect packets.
7.3. Protected Packets Prior to Handshake Completion
Due to reordering and loss, protected packets might be received by an
endpoint before the final handshake messages are received. If these
can be decrypted successfully, such packets MAY be stored and used
once the handshake is complete.
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
handshake, once key agreement has completed. This means that
protected messages need to be decrypted to determine if they are TLS
handshake messages or not. Similarly, "ACK" and "WINDOW_UPDATE"
frames might be needed to successfully complete the TLS handshake.
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Any timestamps present in "ACK" frames MUST be ignored rather than
causing a fatal error. Timestamps on protected frames MAY be saved
and used once the TLS handshake completes successfully.
An endpoint MAY save the last protected "WINDOW_UPDATE" frame it
receives for each stream and apply the values once the TLS handshake
completes. Failing to do this might result in temporary stalling of
affected streams.
8. QUIC-Specific Additions to the TLS Handshake
QUIC uses the TLS handshake for more than just negotiation of
cryptographic parameters. The TLS handshake validates protocol
version selection, provides preliminary values for QUIC transport
parameters, and allows a server to perform return routeability checks
on clients.
8.1. Protocol and Version Negotiation
The QUIC version negotiation mechanism is used to negotiate the
version of QUIC that is used prior to the completion of the
handshake. However, this packet is not authenticated, enabling an
active attacker to force a version downgrade.
To ensure that a QUIC version downgrade is not forced by an attacker,
version information is copied into the TLS handshake, which provides
integrity protection for the QUIC negotiation. This does not prevent
version downgrade during the handshake, though it means that such a
downgrade causes a handshake failure.
Protocols that use the QUIC transport MUST use Application Layer
Protocol Negotiation (ALPN) [RFC7301]. The ALPN identifier for the
protocol MUST be specific to the QUIC version that it operates over.
When constructing a ClientHello, clients MUST include a list of all
the ALPN identifiers that they support, regardless of whether the
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
version it MUST abort the connection. A client MUST abort a
connection if the server picks an incompatible version of QUIC
version and ALPN.
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8.2. QUIC Extension
QUIC defines an extension for use with TLS. That extension defines
transport-related parameters. This provides integrity protection for
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
QUIC implementations describe a source address token. This is an
opaque blob that a server might provide to clients when they first
use a given source address. The client returns this token in
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.
Therefore it can be included in the TLS 1.3 pre-shared key identifier
for 0-RTT handshakes. Servers that use 0-RTT are advised to provide
new pre-shared key identifiers after every handshake to avoid
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
the cookie extension of a HelloRetryRequest.
8.4. Priming 0-RTT
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
enable 0-RTT in QUIC. Similarly, QUIC can provide a pre-shared key
that can be used to enable 0-RTT in TCP.
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
designated as being compatible. The client indicates which ALPN
label it has chosen by placing that ALPN label first in the ALPN
extension.
The certificate that the server uses MUST be considered valid for
both connections, which will use different protocol stacks and could
use different port numbers. For instance, HTTP/1.1 and HTTP/2
operate over TLS and TCP, whereas QUIC operates over UDP.
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Source address validation is not completely portable between
different protocol stacks. Even if the source IP address remains
constant, the port number is likely to be different. Packet
reflection attacks are still possible in this situation, though the
set of hosts that can initiate these attacks is greatly reduced. 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
toward the client without source validation.
9. Security Considerations
There are likely to be some real clangers here eventually, but the
current set of issues is well captured in the relevant sections of
the main text.
Never assume that because it isn't in the security considerations
section it doesn't affect security. Most of this document does.
9.1. Packet Reflection Attack Mitigation
A small ClientHello that results in a large block of handshake
messages from a server can be used in packet reflection attacks to
amplify the traffic generated by an attacker.
Certificate caching [RFC7924] can reduce the size of the server's
handshake messages significantly.
A client SHOULD also pad [RFC7685] its ClientHello to at least 1024
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
receives. A server SHOULD use a HelloRetryRequest if the size of the
handshake messages it sends is likely to exceed the size of the
ClientHello.
9.2. Peer Denial of Service
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
processing resources without having any observable impact on the
state of the connection. If processing is disproportionately large
in comparison to the observable effects on bandwidth or state, then
this could allow a malicious peer to exhaust processing capacity
without consequence.
QUIC prohibits the sending of empty "STREAM" frames unless they are
marked with the FIN bit. This prevents "STREAM" frames from being
sent that only waste effort.
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TLS records SHOULD always contain at least one octet of a handshake
messages or alert. Records containing only padding are permitted
during the handshake, but an excessive number might be used to
generate unnecessary work. Once the TLS handshake is complete,
endpoints SHOULD NOT send TLS application data records unless it is
to hide the length of QUIC records. QUIC packet protection does not
include any allowance for padding; padded TLS application data
records can be used to mask the length of QUIC frames.
While there are legitimate uses for some redundant packets,
implementations SHOULD track redundant packets and treat excessive
volumes of any non-productive packets as indicative of an attack.
10. Error codes
The portion of the QUIC error code space allocated for the crypto
handshake is 0xB000-0xFFFF. The following error codes are defined
when TLS is used for the crypto handshake:
TLS_HANDSHAKE_FAILED (0xB01c): Crypto errors. Handshake failed.
TLS_MESSAGE_OUT_OF_ORDER (0xB01d): Handshake message received out of
order.
TLS_TOO_MANY_ENTRIES (0xB01e): Handshake message contained too many
entries.
TLS_INVALID_VALUE_LENGTH (0xB01f): Handshake message contained an
invalid value length.
TLS_MESSAGE_AFTER_HANDSHAKE_COMPLETE (0xB020): A handshake message
was received after the handshake was complete.
TLS_INVALID_RECORD_TYPE (0xB021): A handshake message was received
with an illegal record type.
TLS_INVALID_PARAMETER (0xB022): A handshake message was received
with an illegal parameter.
TLS_INVALID_CHANNEL_ID_SIGNATURE (0xB034): An invalid channel id
signature was supplied.
TLS_MESSAGE_PARAMETER_NOT_FOUND (0xB023): A handshake message was
received with a mandatory parameter missing.
TLS_MESSAGE_PARAMETER_NO_OVERLAP (0xB024): A handshake message was
received with a parameter that has no overlap with the local
parameter.
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TLS_MESSAGE_INDEX_NOT_FOUND (0xB025): A handshake message was
received that contained a parameter with too few values.
TLS_UNSUPPORTED_PROOF_DEMAND (0xB05e): A demand for an unsupported
proof type was received.
TLS_INTERNAL_ERROR (0xB026): An internal error occured in handshake
processing.
TLS_VERSION_NOT_SUPPORTED (0xB027): A handshake handshake message
specified an unsupported version.
TLS_HANDSHAKE_STATELESS_REJECT (0xB048): A handshake handshake
message resulted in a stateless reject.
TLS_NO_SUPPORT (0xB028): There was no intersection between the
crypto primitives supported by the peer and ourselves.
TLS_TOO_MANY_REJECTS (0xB029): The server rejected our client hello
messages too many times.
TLS_PROOF_INVALID (0xB02a): The client rejected the server's
certificate chain or signature.
TLS_DUPLICATE_TAG (0xB02b): A handshake message was received with a
duplicate tag.
TLS_ENCRYPTION_LEVEL_INCORRECT (0xB02c): A handshake message was
received with the wrong encryption level (i.e. it should have been
encrypted but was not.)
TLS_SERVER_CONFIG_EXPIRED (0xB02d): The server config for a server
has expired.
TLS_SYMMETRIC_KEY_SETUP_FAILED (0xB035): We failed to set up the
symmetric keys for a connection.
TLS_MESSAGE_WHILE_VALIDATING_CLIENT_HELLO (0xB036): A handshake
message arrived, but we are still validating the previous
handshake message.
TLS_UPDATE_BEFORE_HANDSHAKE_COMPLETE (0xB041): A server config
update arrived before the handshake is complete.
TLS_CLIENT_HELLO_TOO_LARGE (0xB05a): ClientHello cannot fit in one
packet.
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11. IANA Considerations
This document has no IANA actions. Yet.
12. References
12.1. Normative References
[I-D.ietf-tls-tls13]
Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", draft-ietf-tls-tls13-18 (work in progress),
October 2016.
[QUIC-TRANSPORT]
Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport".
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated
Encryption", RFC 5116, DOI 10.17487/RFC5116, January 2008,
<http://www.rfc-editor.org/info/rfc5116>.
[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
Key Derivation Function (HKDF)", RFC 5869,
DOI 10.17487/RFC5869, May 2010,
<http://www.rfc-editor.org/info/rfc5869>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <http://www.rfc-editor.org/info/rfc7301>.
[RFC7685] Langley, A., "A Transport Layer Security (TLS) ClientHello
Padding Extension", RFC 7685, DOI 10.17487/RFC7685,
October 2015, <http://www.rfc-editor.org/info/rfc7685>.
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12.2. Informative References
[AEBounds]
Luykx, A. and K. Paterson, "Limits on Authenticated
Encryption Use in TLS", March 2016,
<http://www.isg.rhul.ac.uk/~kp/TLS-AEbounds.pdf>.
[QUIC-HTTP]
Bishop, M., Ed., "Hypertext Transfer Protocol (HTTP) over
QUIC".
[QUIC-RECOVERY]
Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection
and Congestion Control".
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>.
[RFC7924] Santesson, S. and H. Tschofenig, "Transport Layer Security
(TLS) Cached Information Extension", RFC 7924,
DOI 10.17487/RFC7924, July 2016,
<http://www.rfc-editor.org/info/rfc7924>.
Appendix A. Contributors
Ryan Hamilton was originally an author of this specification.
Appendix B. Acknowledgments
This document has benefited from input from Dragana Damjanovic,
Christian Huitema, Jana Iyengar, Adam Langley, Roberto Peon, Eric
Rescorla, Ian Swett, and many others.
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Appendix C. Change Log
*RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document.
C.1. Since draft-ietf-quic-tls-00:
o Changed bit used to signal key phase.
o Updated key phase markings during the handshake.
o Added TLS interface requirements section.
o Moved to use of TLS exporters for key derivation.
o Moved TLS error code definitions into this document.
C.2. Since draft-thomson-quic-tls-01:
o Adopted as base for draft-ietf-quic-tls.
o Updated authors/editors list.
o Added status note.
Authors' Addresses
Martin Thomson (editor)
Mozilla
Email: martin.thomson@gmail.com
Sean Turner (editor)
sn3rd
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