ZLIB Compressed Data Format Specification version 3.3
RFC 1950
Document | Type |
RFC - Informational
(May 1996; No errata)
Was draft-deutsch-zlib-spec (individual)
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Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf ps htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 1950 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group P. Deutsch Request for Comments: 1950 Aladdin Enterprises Category: Informational J-L. Gailly Info-ZIP May 1996 ZLIB Compressed Data Format Specification version 3.3 Status of This Memo This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited. IESG Note: The IESG takes no position on the validity of any Intellectual Property Rights statements contained in this document. Notices Copyright (c) 1996 L. Peter Deutsch and Jean-Loup Gailly Permission is granted to copy and distribute this document for any purpose and without charge, including translations into other languages and incorporation into compilations, provided that the copyright notice and this notice are preserved, and that any substantive changes or deletions from the original are clearly marked. A pointer to the latest version of this and related documentation in HTML format can be found at the URL <ftp://ftp.uu.net/graphics/png/documents/zlib/zdoc-index.html>. Abstract This specification defines a lossless compressed data format. The data can be produced or consumed, even for an arbitrarily long sequentially presented input data stream, using only an a priori bounded amount of intermediate storage. The format presently uses the DEFLATE compression method but can be easily extended to use other compression methods. It can be implemented readily in a manner not covered by patents. This specification also defines the ADLER-32 checksum (an extension and improvement of the Fletcher checksum), used for detection of data corruption, and provides an algorithm for computing it. Deutsch & Gailly Informational [Page 1] RFC 1950 ZLIB Compressed Data Format Specification May 1996 Table of Contents 1. Introduction ................................................... 2 1.1. Purpose ................................................... 2 1.2. Intended audience ......................................... 3 1.3. Scope ..................................................... 3 1.4. Compliance ................................................ 3 1.5. Definitions of terms and conventions used ................ 3 1.6. Changes from previous versions ............................ 3 2. Detailed specification ......................................... 3 2.1. Overall conventions ....................................... 3 2.2. Data format ............................................... 4 2.3. Compliance ................................................ 7 3. References ..................................................... 7 4. Source code .................................................... 8 5. Security Considerations ........................................ 8 6. Acknowledgements ............................................... 8 7. Authors' Addresses ............................................. 8 8. Appendix: Rationale ............................................ 9 9. Appendix: Sample code ..........................................10 1. Introduction 1.1. Purpose The purpose of this specification is to define a lossless compressed data format that: * Is independent of CPU type, operating system, file system, and character set, and hence can be used for interchange; * Can be produced or consumed, even for an arbitrarily long sequentially presented input data stream, using only an a priori bounded amount of intermediate storage, and hence can be used in data communications or similar structures such as Unix filters; * Can use a number of different compression methods; * Can be implemented readily in a manner not covered by patents, and hence can be practiced freely. The data format defined by this specification does not attempt to allow random access to compressed data. Deutsch & Gailly Informational [Page 2] RFC 1950 ZLIB Compressed Data Format Specification May 1996 1.2. Intended audience This specification is intended for use by implementors of software to compress data into zlib format and/or decompress data from zlib format. The text of the specification assumes a basic background in programming at the level of bits and other primitive data representations. 1.3. Scope The specification specifies a compressed data format that can be used for in-memory compression of a sequence of arbitrary bytes.Show full document text