Internet DRAFT - draft-levine-application-gzip
draft-levine-application-gzip
Network Working Group J.R. Levine
Internet-Draft Taughannock Networks
Intended status: Informational June 2012
Expires: December 13, 2012
The application/zlib and application/gzip media types
draft-levine-application-gzip-03
Abstract
This document defines the 'application/gzip' and 'application/zlib'
media types for compressed data using the gzip and zlib compression
formats.
Status of this Memo
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This Internet-Draft will expire on December 13, 2012.
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document authors. All rights reserved.
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1. Introduction
The Zlib [RFC1950] and gzip [RFC1952] formats are widely used
compression formats. Zlib is a stream format, while gzip adds header
and trailer fields more appropriate for a file format. Both
implement the DEFLATE compression scheme described in [RFC1951].
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They are used to compress a wide variety of material, from
unstructured text to structured data to executable code.
Some applications have informally used media types including
application/gzip-compressed, application/gzipped, application/
x-gunzip, application/x-gzip, application/x-gzip-compressed, and gzip
/document to describe data compressed with gzip. The media types
defined in this document should replace those media types in future
applications.
2. The Application/Zlib Media Type
The application/zlib media type describes a block of data that is
compressed using Zlib [RFC1950] compression. The data is a stream of
bytes as described in RFC 1950.
2.1. Registration Details
Type name: application
Subtype name: zlib
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: Binary.
Security considerations: See section [security] below
Interoperability considerations: N/A
Published specification: [RFC1950]
Applications that use this media type: anywhere data size is an issue
Additional information:
Magic number(s): first byte is usually 0x78 but can also be 0x08,
0x18, 0x28, 0x38, 0x48, 0x58, or 0x68. The first two bytes when
interpreted as an unsigned 16-bit number in big-endian byte order
contain a value that is a multiple of 31.
File extension(s): N/A
Macintosh file type code(s): N/A
Person and email address to contact for further information: see
http://www.zlib.net/
Intended usage: COMMON
Restrictions on usage: N/A
Author: John Levine
Change controller: IETF
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3. The Application/Gzip Media Type
The application/gzip media type describes a block of data that is
compressed using gzip [RFC1952] compression. The data is a stream of
bytes as described in RFC 1952.
3.1. Registration Details
Type name: application
Subtype name: gzip
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: Binary.
Security considerations: See section [security] below
Interoperability considerations: N/A
Published specification: [RFC1952]
Applications that use this media type: anywhere data size is an issue
Additional information:
Magic number(s): first two bytes are 0x1f, 0x8b.
File extension(s): gz
Macintosh file type code(s): N/A
Person and email address to contact for further information: see
http://www.gzip.org/
Intended usage: COMMON
Restrictions on usage: N/A
Author: John Levine
Change controller: IETF
4. Security Considerations
Zlib and gzip compression can be used to compress arbitrary binary
data such as hostile executable code. Also, data that purports to be
in zlib or gzip format may not be, and fields that are supposed to be
flags, lengths, or pointers could contain anything. Applications
should treat any data with due skepticism.
Also see the security considerations in the underlying format
documents, Section 5 of [RFC1950], Section 6 of [RFC1951], and
Section 4 of [RFC1952].
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5. IANA Considerations
IANA is requested to update the MIME Media Types registry to include
application/zlib as described in Section [zlib] and application/gzip
as described in Section [gzip].
6. References
[RFC1950] Deutsch, L.P. and J-L. Gailly, "ZLIB Compressed Data
Format Specification version 3.3", RFC 1950, May 1996.
[RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification
version 1.3", RFC 1951, May 1996.
[RFC1952] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L.P. and G.
Randers-Pehrson, "GZIP file format specification version
4.3", RFC 1952, May 1996.
Appendix A. Change log
Note to editor: Please remove this section before publication.
Appendix A.1. Changes from -02 to -03
Add IANA considerations
Simplify encoding: binary and fix typos
Appendix A.2. Changes from -01 to -02
Fix gzip.org
Note other former names
Appendix A.3. Changes from -00 to -01
Note former x-gzip
Refer to security sections in underlying format docs
Author's Address
John Levine
Taughannock Networks
PO Box 727
Trumansburg, NY 14886
Phone: +1 831 480 2300
Email: standards@taugh.com
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