Lzip Compressed Format and the application/lzip Media Type
draft-diaz-lzip-02
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Antonio Diaz
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2020-10-23
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Internet Engineering Task Force (IETF) A. Diaz
INTERNET-DRAFT draft-diaz-lzip-02 GNU Project
Category: Informational October 2020
Expiration date: 2021-04-26
Lzip Compressed Format and the application/lzip Media Type
Abstract
Lzip is a lossless compressed data format designed for data sharing,
long-term archiving, and parallel compression/decompression. Lzip
uses a simplified form of the Lempel-Ziv-Markov chain-Algorithm
(LZMA) stream format, chosen to maximize safety and interoperability.
Lzip can achieve higher compression ratios than gzip. This document
describes the lzip format and registers a media type and content
encoding to be used when transporting lzip-compressed content via
Multipurpose Internet Mail Extensions (MIME).
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc<rfc-no>.
Comments are solicited and should be addressed to the lzip's mailing
list at lzip-bug@nongnu.org and/or the author.
Diaz Informational [Page 1]
draft-diaz-lzip-02 application/lzip October 2020
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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
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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.
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provisions of BCP 78 and BCP 79. Internet-Drafts are working
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Compliance . . . . . . . . . . . . . . . . . . . . . . . 4
2. File Format . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Format of the LZMA stream in lzip files . . . . . . . . . . . 5
3.1. What is coded . . . . . . . . . . . . . . . . . . . . . 6
3.2. The coding contexts . . . . . . . . . . . . . . . . . . 8
3.3. The range decoder . . . . . . . . . . . . . . . . . . . 10
3.4. Decoding and verifying the LZMA stream . . . . . . . . . 10
3.5. Compression . . . . . . . . . . . . . . . . . . . . . . 10
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
4.1. The 'application/lzip' Media Type . . . . . . . . . . . 11
4.2. Content Encoding . . . . . . . . . . . . . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. Normative References . . . . . . . . . . . . . . . . . . 13
6.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Reference Source Code . . . . . . . . . . . . . . . 13
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 23
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 23
Diaz Informational [Page 2]
draft-diaz-lzip-02 application/lzip October 2020
1. Introduction
Lzip is a lossless compressed data format similar to gzip [RFC1952].
Lzip is designed for data sharing, long-term archiving, parallel
compression/decompression, and limited random access to the data.
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