Lzip Compressed Format and the application/lzip Media Type
draft-diaz-lzip-00

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 00

Internet Engineering Task Force (IETF)                           A. Diaz
INTERNET-DRAFT  draft-diaz-lzip-00                           GNU Project
Category: Informational                                     October 2019
Expiration date: 2020-04-26

       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 (de)compression.  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-00          application/lzip                October 2019

Copyright Notice

   Copyright (c) 2019 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
   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.

Internet-Draft Boilerplate

   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."

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-00          application/lzip                October 2019

1.  Introduction

   Lzip is a lossless compressed data format similar to gzip [RFC1952].
   Lzip is designed for data sharing, long-term archiving, parallel
   (de)compression, and limited random access to the data.  Lzip can