Internet DRAFT - draft-banks-quic-disable-encryption
draft-banks-quic-disable-encryption
Network Working Group N. Banks
Internet-Draft Microsoft Corporation
Intended status: Experimental August 11, 2020
Expires: February 12, 2021
QUIC Disable Encryption
draft-banks-quic-disable-encryption-00
Abstract
The disable_1rtt_encryption transport parameter can be used to
negotiate the disablement of encryption on 1-RTT packets, allowing
for reduced CPU load and improved performance. This extension is
only meant to be used in environments where both endpoints completely
trust the path between themselves; not, for instance, on the open
internet.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on February 12, 2021.
Copyright Notice
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terms and Definitions . . . . . . . . . . . . . . . . . . 2
1.2. Applicable Scenarios for Use . . . . . . . . . . . . . . 2
2. Specification . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Disable 1-RTT Encryption Transport Parameter . . . . . . 3
2.2. Negotiating the Extension . . . . . . . . . . . . . . . . 3
2.3. Disabling 1-RTT Encryption . . . . . . . . . . . . . . . 4
2.4. Interactions with Path Changes . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Normative References . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
By default QUIC Transport Protocol [I-D.ietf-quic-transport] provides
secured (authenticated and encrypted) connections via a TLS
handshake. The handshake allows for the endpoints to be
authenticated by a certificate and then securely generates shared
secrets to encrypt the QUIC packet traffic. Post-handshake, this
packet encryption can occupy a considerable percentage of CPU usage,
depending on the scenario. Additionally, there are scenarios where
the protections given by this encryption are either unnecessary or
unwanted. For these scenarios, this document defines an extension to
the QUIC protocol to allow for mutually participating endpoints to
negotiate the disablement of encryption for the 1-RTT packets sent
after the handshake.
1.1. Terms and Definitions
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. Applicable Scenarios for Use
QUIC connections are generally meant to always be encrypted, to
prevent unauthenticated middleboxes from reading or modifying the
QUIC packets. This is the desired behavior for most environments;
especially any that go over the open internet. There are two
possible scenarios where disabling packet encryption makes sense:
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o Trusted Environment/Path - There are scenarios or environments
where there is no need for the additional security measures of
QUIC encryption; such as walled-gardens or tunneled connections.
These scenarios are either already trusted or secured by other
means.
o Performance Testing - When the actual contents of the QUIC packets
are unimportant and the goal is purely to measure the performance
characteristics of either the network, machine or QUIC
implementation without encryption.
2. Specification
The disable_1rtt_encryption transport parameter used for negotiating
the use of the extension is defined below.
2.1. Disable 1-RTT Encryption Transport Parameter
The disable_1rtt_encryption transport parameter can be sent by both a
client and server. The transport parameter is sent with an optional
variable-length value by the client and an empty value by the server;
a client that understands this transport parameter MUST treat the
receipt of a non-empty value as a connection error of type
TRANSPORT_PARAMETER_ERROR.
Advertising the disable_1rtt_encryption transport parameter indicates
that the endpoint wishes to disable encryption for 1-RTT packets.
Both sides must advertise support for the feature for it to be
considered successfully negotiated.
If successfully negotiated, all packets that would normally be
encrypted with the 1-RTT key are instead sent as cleartext; both
header and packet protections are disabled.
2.2. Negotiating the Extension
The payload sent in the transport parameter by the client, along with
any other information the server has about the client (such as IP
address) may be used to negotiate the extension on the server side.
The TP payload could be considered a key or identifier used by the
server to verify the client should be allowed to disable encryption.
These additional security measures are optional, but RECOMMENDED to
ensure encryption is not accidentally enabled when it should not be.
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2.3. Disabling 1-RTT Encryption
When the extension is negotiated, all aspects of encryption on 1-RTT
packets are removed:
o Header protection
o Payload protection
o AEAD tag
This effectively gives the transport an additional 16 bytes per
packet to be used for payload, since it is no longer including an
AEAD tag.
Because the AEAD tag is removed along with the encryption, the UDP
checksum must be relied upon to determine any packet corruption.
2.4. Interactions with Path Changes
When making the trust determination about the path, each endpoints
must take into account possible path changes; NAT rebinding for
instance. An endpoint MUST NOT enable enable this extension if it is
possible for the path to change during the connection to some
untrusted state.
Additionally, a client MUST NOT try to migrate to any path that is
untrusted if this extension is negotiated. If a server receives a
packet for a connection with this extension negotiated on an
untrusted path, it MUST silently drop the packet.
3. Security Considerations
Disabling encryption for 1-RTT packets has some fairly obvious
security drawbacks:
o Packets can be read, modified and injected by any middleboxes
This extension is not meant to be used for any practical application
protocol on the open internet. Internet facing servers MUST NOT
enable this extension. Clients that do not trust their network and
path to the server MUST NOT enable this extension.
This extension does not modify the packet protections used during the
handshake, so the handshake can still be securely authenticated.
This prevents scenarios where one endpoint might trust (or think it
trusts) the path, but the other endpoint does not, and a man-in-the-
middle tries to force this extension to be used.
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To prevent accidental use of the feature on production systems it is
RECOMMENDED for servers to have additional measures such as IP
filtering or a security key.
4. IANA Considerations
This document registers a new value in the QUIC Transport Parameter
Registry:
Value: TBD (using value 0xBAAD in early deployments)
Parameter Name: disable_1rtt_encryption
Specification: Indicates disabled 1-RTT encryption is being
negotiated
5. Normative References
[I-D.ietf-quic-transport]
Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", draft-ietf-quic-transport-29 (work
in progress), June 2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Author's Address
Nick Banks
Microsoft Corporation
Email: nibanks@microsoft.com
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