draft-ietf-tls-compression-04.txt   draft-ietf-tls-compression-05.txt 
Network Working Group S. Hollenbeck Network Working Group S. Hollenbeck
Internet-Draft VeriSign, Inc. Internet-Draft VeriSign, Inc.
Updates: 2246 (if approved) December 2, 2002 Updates: 2246 (if approved) May 27, 2003
Expires: June 2, 2003 Expires: November 25, 2003
Transport Layer Security Protocol Compression Methods Transport Layer Security Protocol Compression Methods
draft-ietf-tls-compression-04.txt draft-ietf-tls-compression-05.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
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This Internet-Draft will expire on June 2, 2003. This Internet-Draft will expire on November 25, 2003.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract Abstract
The Transport Layer Security (TLS) protocol (RFC 2246) includes The Transport Layer Security (TLS) protocol (RFC 2246) includes
features to negotiate selection of a lossless data compression method features to negotiate selection of a lossless data compression method
as part of the TLS Handshake Protocol and to then apply the algorithm as part of the TLS Handshake Protocol and to then apply the algorithm
associated with the selected method as part of the TLS Record associated with the selected method as part of the TLS Record
Protocol. TLS defines one standard compression method which Protocol. TLS defines one standard compression method which
specifies that data exchanged via the record protocol will not be specifies that data exchanged via the record protocol will not be
compressed. This document describes an additional compression method compressed. This document describes an additional compression method
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Conventions Used In This Document Conventions Used In This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [1]. document are to be interpreted as described in RFC 2119 [1].
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Compression Methods . . . . . . . . . . . . . . . . . . . . . 3 2. Compression Methods . . . . . . . . . . . . . . . . . . . . . 4
2.1 Compression History and Packet Processing . . . . . . . . . . 4 2.1 Compression History and Packet Processing . . . . . . . . . . 5
2.2 ZLIB Compression . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 ZLIB Compression . . . . . . . . . . . . . . . . . . . . . . . 5
3. Intellectual Property Considerations . . . . . . . . . . . . . 5 3. Intellectual Property Considerations . . . . . . . . . . . . . 6
4. Internationalization Considerations . . . . . . . . . . . . . 5 4. Internationalization Considerations . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
Normative References . . . . . . . . . . . . . . . . . . . . . 6 Normative References . . . . . . . . . . . . . . . . . . . . . 11
Informative References . . . . . . . . . . . . . . . . . . . . 6 Informative References . . . . . . . . . . . . . . . . . . . . 12
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 12
Full Copyright Statement . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . 13
1. Introduction 1. Introduction
The Transport Layer Security (TLS) protocol (RFC 2246, [2]) includes The Transport Layer Security (TLS) protocol (RFC 2246, [2]) includes
features to negotiate selection of a lossless data compression method features to negotiate selection of a lossless data compression method
as part of the TLS Handshake Protocol and to then apply the algorithm as part of the TLS Handshake Protocol and to then apply the algorithm
associated with the selected method as part of the TLS Record associated with the selected method as part of the TLS Record
Protocol. TLS defines one standard compression method, Protocol. TLS defines one standard compression method,
CompressionMethod.null, which specifies that data exchanged via the CompressionMethod.null, which specifies that data exchanged via the
record protocol will not be compressed. While this single record protocol will not be compressed. While this single
compression method helps ensure that TLS implementations are compression method helps ensure that TLS implementations are
interoperable, the lack of additional standard compression methods interoperable, the lack of additional standard compression methods
has limited the ability of implementers to develop interoperable has limited the ability of implementers to develop interoperable
implementations that include data compression. implementations that include data compression.
TLS is used extensively to secure client-server connections on the TLS is used extensively to secure client-server connections on the
World Wide Web. While these connections can often be characterized World Wide Web. While these connections can often be characterized
as short-lived and exchanging relatively small amounts of data, TLS as short-lived and exchanging relatively small amounts of data, TLS
is also being used in environments where connections can be long- is also being used in environments where connections can be
lived and the amount of data exchanged can extend into thousands or long-lived and the amount of data exchanged can extend into thousands
millions of octets. XML [4], for example, is increasingly being used or millions of octets. XML [4], for example, is increasingly being
as a data representation method on the Internet, and XML tends to be used as a data representation method on the Internet, and XML tends
verbose. Compression within TLS is one way to help reduce the to be verbose. Compression within TLS is one way to help reduce the
bandwidth and latency requirements associated with exchanging large bandwidth and latency requirements associated with exchanging large
amounts of data while preserving the security services provided by amounts of data while preserving the security services provided by
TLS. TLS.
This document describes an additional compression method associated This document describes an additional compression method associated
with a lossless data compression algorithm for use with TLS. with a lossless data compression algorithm for use with TLS.
Standardization of the compressed data formats and compression Standardization of the compressed data formats and compression
algorithms associated with this compression method is beyond the algorithms associated with this compression method is beyond the
scope of this document. scope of this document.
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needed to completely decompress data contained in a different packet. needed to completely decompress data contained in a different packet.
History maintenance thus requires both a reliable link and sequenced History maintenance thus requires both a reliable link and sequenced
packet delivery. Since TLS and lower-layer protocols provide packet delivery. Since TLS and lower-layer protocols provide
reliable, sequenced packet delivery, compression history information reliable, sequenced packet delivery, compression history information
MAY be maintained and exploited if supported by the compression MAY be maintained and exploited if supported by the compression
method. method.
2.2 ZLIB Compression 2.2 ZLIB Compression
The ZLIB compression method and encoding format is described in RFC The ZLIB compression method and encoding format is described in RFC
1950 [5] and RFC 1951 [6]. Examples of ZLIB use in IETF protocols 1950 [5] and RFC 1951 [6]. Examples of ZLIB use in IETF protocols can
can be found in RFC 1979 [7], RFC 2394 [8], and RFC 3274 [9]. be found in RFC 1979 [7], RFC 2394 [8], and RFC 3274 [9].
ZLIB allows the sending compressor to select from among several ZLIB allows the sending compressor to select from among several
options to provide varying compression ratios, processing speeds, and options to provide varying compression ratios, processing speeds, and
memory requirements. The receiving decompressor MUST automatically memory requirements. The receiving decompressor MUST automatically
adjust to the parameters selected by the sender. All data that was adjust to the parameters selected by the sender. All data that was
submitted for compression MUST be included in the compressed output, submitted for compression MUST be included in the compressed output,
with no data retained to be included in a later output payload. with no data retained to be included in a later output payload.
Flushing ensures that each compressed packet payload can be Flushing ensures that each compressed packet payload can be
decompressed completely. decompressed completely.
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Author's Address Author's Address
Scott Hollenbeck Scott Hollenbeck
VeriSign, Inc. VeriSign, Inc.
21345 Ridgetop Circle 21345 Ridgetop Circle
Dulles, VA 20166-6503 Dulles, VA 20166-6503
US US
EMail: shollenbeck@verisign.com EMail: shollenbeck@verisign.com
Intellectual Property Statement
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Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
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Acknowledgement Acknowledgement
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