Network Working Group A. Langley
Internet-Draft Google Inc
Expires: May 5, 2014 Nov 2013
A TLS padding extension
draft-agl-tls-padding-00
Abstract
This memo describes the a TLS extension that can be used to pad
ClientHello messages to a desired size.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 5, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . . 4
3. Padding Extension . . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Successive TLS [RFC5246] versions have added support for more cipher
suites and, over time, more TLS extensions have been defined. This
has caused the size of the TLS ClientHello to grow and the additional
size has caused some implementation bugs to come to light. At least
some of these implementation bugs can be ameliorated by making the
ClientHello even larger.
This memo describes a TLS extension that can be used to pad a
ClientHello to a desired size in order to avoid implementation bugs
caused by certain ClientHello sizes.
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2. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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3. Padding Extension
A new extension type (""padding(TBD)"") is defined and MAY be
included by the client in its ClientHello message.
enum {
padding(TBD), (65535)
} ExtensionType
The server MUST ignore the presence of the extension and its
contents. As a consequence, the server MUST NOT echo the extension.
The client MAY fill the padding extension with zero or more,
arbitrary bytes. As the contents of the extension are completely
arbitrary, no structure is defined here.
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4. IANA Considerations
IANA is requested to assign an extension value for the padding
extension from its ExtensionType registry.
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5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
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Author's Address
Adam Langley
Google Inc
Email: agl@google.com
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