PKZIP

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PKZIP 2.04g for DOS, circa 1993.

PKZIP is an archiving tool originally written by Phil Katz and marketed by his company PKWARE, Inc. PKZIP is an acronym for Phil Katz's ZIP program.

Contents

[edit] History

File compression routines date back to at least the 1960s: IBM had a compression program called SQUOZE that was commonly used to pack programs on the 709 and 7090 mainframes as part of the SHARE operating system. Previous programs almost certainly existed.

By the 1970s file archiving programs were distributed as standard utilities with operating systems. They include the Unix utilities ar, shar, and tar. These utilities were designed to gather a number of separate files into a single archive file for easier copying and distribution.

Other archivers also appeared during the 1980s, including Rahul Dhesi's ZOO, Dean W. Cooper's DWC, LHarc by Haruhiko Okomura and Haruyasu Yoshizaki and ARJ which stands for Archived by Robert Jung.

The devlopment of PKZIP was first announced in a the file SOFTDEV.DOC from within the PKPAK 3.61 package, stating it would develop a new and yet unnamed compression program. The announcement had been made following the ARC lawsuit between System Enhancement Associates, Inc. and PKWARE, Inc.

The first version was released in 1989 as a DOS command-line tool, distributed under shareware model with a $25US registration fee ($47US with manual).

[edit] Version history

PKZIP 0.9 (1989-02-01) supports Reducing algorithm (from SCRNCH by Graeme McRae)[1] with 4 compression settings and shrinking. In addition to PKZIP and PKUNZIP, it also included ZIP2EXE, which reqires an external self-extracting executable header created by MAKESFX from the PKZIP executable package.

PKZIP 0.92 (1989-03-06): In addition to bug fixes, PKZIP now includes an option to automatically choose the best compression method for each file. New tools included with PKZIP include PKZipFix.

PKZIP 1.01 (1989-07-21) added Implode compression, while Reduced files can only be extracted from ZIP archive. Impoding was chosen based on the characteristics of the file being compressed.[2] New utility includes Thomas Atkinson's REZIP conversion utilty (part of ZIP-KIT). PKZIP's default compression behaviour was changed to fastest (Shrink) to best (Implode). Supported platforms include OS/2, DOS.

PKZIP 1.02 (1989-10-01) includes new utility BIOSFIX.COM, which preserves the entire 80386 register set during any mode switches via INT 15H. OS/2 version added ZIP2EXE and 2 self-extracting archive headers.

PKZIP 1.10 (1990-03-15): New features include Authenticity Verification, "mini" PKSFX self-extracting module, integrating self-extracting module into ZIP2EXE, ability to save & restore volume labels. Imploding is up to 5X faster and compression ratio is improved over 1.02. EAX register is always saved on 80386 or above CPU. Removed tools include BIOSFIX, REZIP, MAKESFX.

In 1993, PKWARE released PKZIP 2.0. This new version dispensed with the miscellaneous compression methods of PKZIP 1.x and replaced them with a single new compression method which Katz called "deflating" (although several compression levels of deflating were provided by the program). The resulting file format has since become ubiquitous on Microsoft Windows and on the Internet - almost all files with the .ZIP (or .zip) extension are in PKZIP 2.x format, and utilities to read and write these files are available on all common platforms. PKZIP 2.x also supports spanning archives to multiple disk, which simply splits the files into multiple pieces, and using volume label on each drive to differentiate each other. A new Authenticity Verification (AV) signature format is used. Registered version includes PKUNZJR, PK Safe ANSI, PKCFG utilities.

PKZIP 2.06 was released in 1994. It is a version of PKZIP 2.04g licensed to IBM.[3]

PKZIP 2.50 was the first version released for Windows 3.1, 95, NT platforms. DOS version of PKZIP 2.50 was released on 1999-03-01, as its final MS-DOS product. PKZIP 2.50 supports long file names on all builds, and Deflate64 extraction. DCL Implode extraction is supported on non-DOS ports. A new command-line product is debuted in Windows 95, OS/2, UNIX platforms, called "PKZIP Command Line" (later expanded to "PKZIP Server"), which features new command line syntax.

PKZIP 2.6 is the last version supporting Windows 3.1, Windows NT for DEC Alpha and PowerPC platforms.

PKZIP 2.70 adds Email MAPI (i.e. Send To) Support. Registered version include creation of configurable self-extracted archives, adds Authenticity Verification (AV) Information. Distribution Licensed versions include enhanced self-extractors. Professional Distribution Licensed version can create Self-Extracting Patch Files, and includes Self-Extractors for Several New Platforms.

PKZIP 4.0 is an updated version of PKZIP 2.7. Version 3 was skipped as a result of PKZIP 3.0 trojan.[4] It supports Deflate64 and DCL Implode compression, and the use of X.509 v3 certificate-based authentication.[5], creation of Span or Split large .ZIP archives. Old PKZIP command line conversion tools are introduced.

On 2001-08-21, PKWARE announced the availability of PKZIP 4.5.[6] PKZIP 4.5 includes ZIP64 archives support, which allows more than 65535 files per ZIP archives, and storing files larger than 4 gigabytes into .ZIP archive. A version called PKZIP Suite 4.5 also includes PKZIP Command Line 4.5, PKZIP Explorer 1.5, PKZIP Attachments 1.1, and PKZIP Plug-In 1.0.

PKZIP 5.0 was announced in 2002[7], which introduced Strong Encryption Specification (SES) for the Professional version of the product, which initially included DES, 3DES, RC2, RC4 encryption formats, and the use of using X.509 v3 certificate-based encryption.

PKZIP 6.0 was released in 2003, which supports BZip2 (based on Burrows-Wheeler transform) compression, with Professional Edition supporting 256-bit AES.[8]

PKZIP 7.0 changed SES to use non-OAEP key wrapping. Support of creating AV authenticity verification archives was dropped. PKZIP can now create archives of the following types: ZIP, BZIP2, GZIP, TAR, UUEncoded, XXEncoded.

PKZIP 8.0 was released on 2004-04-27.[9] In addition, PKWARE renamed its PKZip Professional to SecureZIP.[10] Creation of ZIP archives with encrypted headers is available.

PKZIP 9.0 is the first version to unofficially support Windows Vista (as administrator).[11] Creation of RC2, DES-encrypted ZIP archives are dropped.

PKZIP 10 Enterprise Edition and SecureZIP 10 were released on i5/OS. It offered the ability to create ZIP64 archives for the target platform.[12] Desktop PKZIP version was no longer developed beyond version 9.

On 2007-04-24, PKWARE announced the release of SecureZIP Standard Version 11 as freeware, available on www.securezip.com. [13] SecureZIP comes with SecureZIP Standard (SecureZIP for Windows Desktop), SecureZIP Enterprise, SecureZIP Command Line Interface, SecureZIP for Server, SecureZIP for Server with Directory Integration Module. At this point, only PKZIP for server remained in development. It added UTF-8 file name support, secure exchange of emails and attachments directly from Outlook or Office applications.

SecureZIP 11.2 added SHA-2 hashing (SHA-256, SHA-384, SHA-512 supported), FIPS-140 security mode.[14]

SecureZIP 12 was released on 2008-2[15].

SecureZIP 12.1 was released on 2008-06-03[16] Freeware SecureZIP includes a free digital certificate and inclusion in the SecureZIP Global Directory. The certificate was supplied by Comodo.[17] Registration key was changed so keys from versions 8 or earlier no longer work.

SecureZIP 12.2 introduced SecureZIP Express, while SecureZIP Standard became shareware. SecureZIP Express does not include the Microsoft Office integration, but the registration cost was reduced to $19.95. Registration key was changed so previous keys no longer work.

SecureZIP 12.3 added support of PPMd, LZMA compressions. Desktop version added Federal Desktop Core Configuration compatibility, 64-bit OS support, ability to rename a ZIP attachment when sending email, improved support for Windows Vista dialogs. Enterprise version added expanded support for setting policy for 64-bit systems.[18]

[edit] .ZIP file format

Main article: ZIP (file format)

To help ensure the interoperability of the ZIP format, Phil Katz published the original .ZIP File Format Specification in the APPNOTE.TXT documentation file. PKWARE continued to maintain this document and periodically published updates. Originally only bundled with registered versions of PKZIP, it was later available on the PKWARE site.

The specification has its own version number, which does not necessarily correspond to the PKZIP version numbers, especially with PKZIP 6 or later. At various times, PKWARE adds preliminary features that allows PKZIP products to extract archives using advanced features, but PKZIP products that create such archives won't be available until the next major release.

[edit] Compatibility

Although popular at the time, ZIP archives utilizing PKZIP 1.0 compression methods are now rare, and many modern unzip tools are unable to handle "shrinking" and "reducing", although "imploding" is usually supported.

[edit] Patents

Shrinking uses dynamic LZW, which Unisys held patents; the patent for the Reduce algorithm had also been filed on June 19, 1984, long before PKZIP had been produced.[19]

[edit] Other products

PKWARE also used its PKZIP standards on following products:

  • PartnerLink (including SecureZIP/PartnerLink, SecureZIP Partner)
  • PKZIP Explorer

[edit] See also

[edit] References

  1. ^ PKZIP 0.90 review (1989-02-21)
  2. ^ How to Become LZW Free
  3. ^ comp.compression FAQ: What is the latest PKZIP version?
  4. ^ Malicious Code 101 Definitions and Background
  5. ^ A new look for an old friend: PKZip Suite 4.5
  6. ^ PKWARE Improves Efficiency and Security of Internet and Enterprise Network File Distribution
  7. ^ PKWARE Announces Security-Enabled PKZIP 5.0
  8. ^ PKZIP Professional Edition 6.0 with Secure Desktop: Secure and compact
  9. ^ PKWare PKZip for Windows 8.0
  10. ^ PKWARE Releases New Version of PKZIP for Windows
  11. ^ PKWARE Responses to Vista Readiness
  12. ^ SecureZIP for i5/OS - FAQs
  13. ^ PKWARE Announces Free-For-Life Simplified Personal Data Security Software
  14. ^ SecureZIP for Windows Desktop v11
  15. ^ New version of SecureZip
  16. ^ New SecureZIP for Windows Desktop Brings Public Key Cryptography to Every Type of User
  17. ^ SecureZIP Standard Edition for Windows Desktop 12.1
  18. ^ Product Updates
  19. ^ 8 What about patents on data compression algorithms?

[edit] External links

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Data compression software implementations
Video compression
(Comparison)
Others
CineForm · Dirac · Indeo · libavcodec · SBC · Sorenson · VP7 · libtheora · WMV
Audio compression
(Comparison)
Archivers
(Comparison)
7-Zip · Ark · bzip2 · compress · File Roller · gzip · Info-ZIP · KGB Archiver · lzop · PAQ · PeaZip · The Unarchiver · tar · Xarchiver
ARC · ALZip · Archive Utility · ARJ · JAR · MacBinary · PKZIP/SecureZIP · PowerArchiver · Squeez · StuffIt · WinAce · WinRAR · WinZip
ARC · ARJ · JAR · Info-ZIP · LHA · lzop · PAQ · PKZIP · RAR · UPX · UHarc · tar
See Compression Methods for methods and Compression Formats and Standards for formats
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