World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0000093769
Reproduction Date:

Title: Pkzip  
Author: World Heritage Encyclopedia
Language: English
Subject: Phil Katz, ARJ, Data compression, WinZip, WavPack
Collection: Data Compression Software, File Archivers, Windows Compression Software
Publisher: World Heritage Encyclopedia


PKZIP 2.04g for DOS, circa 1993
Original author(s) Phil Katz
Developer(s) PKWARE Inc
Type archiving and data compression tool

PKZIP is a file archiving computer program, notable for introducing the popular ZIP file format. PKZIP was first introduced for MS-DOS on the IBM-PC compatible platform in 1989. Since then versions have been released for a number of other architectures and operating systems. PKZIP was originally written by Phil Katz and marketed by his company PKWARE, Inc, with both of them bearing his initials: 'PK'.


  • History 1
    • Version history 1.1
      • PKZIP 1.1.1
      • SecureZIP 1.1.2
  • .ZIP file format 2
  • Compatibility 3
  • Patents 4
  • Other products 5
  • See also 6
  • References 7
  • External links 8
    • Official 8.1
    • Other 8.2


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. These archives could optionally be passed through a stream compressor utility, such as compress and others.

Other archivers also appeared during the 1980s, including ARC by System Enhancement Associates, Inc. (SEA), 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 development of PKZIP was first announced in 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 lawsuit between SEA and PKWARE, Inc. Although SEA won the suit, it lost the compression war, as the user base migrated to PKZIP as the compressor of choice. Led by BBS sysops who refused to accept or offer files compressed as .ARC files, users began recompressing any old archives that were currently stored in .ARC format into .ZIP files.

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).

Version history


  • PKZIP 0.8 (1989-01-11) initial version
  • PKZIP 0.9 (1989-02-10) supported 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 required 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 included 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. Imploding was chosen based on the characteristics of the file being compressed.[2] New utility included Thomas Atkinson's REZIP conversion utility (part of ZIP-KIT). PKZIP's default compression behavior was changed from fastest (Shrink) to best (Implode). Supported platforms include OS/2, DOS.
  • PKZIP 1.02 (1989-10-01) includes new utility BIOSFIX.COM, which preserved 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 included Authenticity Verification, "mini" PKSFX self-extracting module, integrating self-extracting module into ZIP2EXE, ability to save & restore volume labels. Imploding was up to 5X faster and compression ratio was improved over 1.02. EAX register was always saved on 80386 or above CPU. Removed tools included 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 supported spanning archives to multiple disk, which simply split the files into multiple pieces, and using volume label on each drive to differentiate each other. A new Authenticity Verification (AV) signature format was used. Registered version included PKUNZJR, PK Safe ANSI, PKCFG utilities.
  • PKZIP 2.06 was released in 1994. It was a version of PKZIP 2.04g licensed to IBM.[3]
  • PKZIP 2.50 (1998-04-15) 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 supported long file names on all builds, and Deflate64 extraction. DCL Implode extraction was supported on non-DOS ports. A new command-line product was introduced in Windows 95, OS/2, UNIX platforms, called "PKZIP Command Line" (later expanded to "PKZIP Server"), which featured new command line syntax.
  • PKZIP 2.6 was the last version to support Windows 3.1 and Windows NT for the Alpha and PowerPC platforms.
  • PKZIP 2.70 added Email MAPI (i.e. Send To) Support. Registered version included creation of configurable self-extracted archives, added Authenticity Verification (AV) Information. Distribution Licensed versions included enhanced self-extractors. Professional Distribution Licensed version could create Self-Extracting Patch Files, and includes Self-Extractors for Several New Platforms.
  • PKZIP 4.0 was an updated version of PKZIP 2.7. Version 3 was skipped as a result of PKZIP 3.0 trojan.[4] It supported 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 were introduced.
  • On 2001-08-21, PKWARE announced the availability of PKZIP 4.5.[6] PKZIP 4.5 included ZIP64 archives support, which allowed 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 included 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 7.0 changed SES to use non-OAEP key wrapping for compatibility with smart cards and USB tokens. Support of creating AV authenticity verification archives was dropped. PKZIP could 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 was available.
  • PKZIP 9.0 was 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[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 did 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.
  • SecureZIP 12.4 was released on 2009-12-14 now supports operation on Windows 7, option to switch to "Office fluent"-style ribbon GUI, 64-bit edition for use with 64-bit versions of Windows Vista and Windows 7.
  • SecureZIP 12.5 (released on 2010-05-12) added integration with Microsoft Office 2010, custom alternative extensions for mailed .ZIP archives, extracting WavPack files within ZIP archives, extracting files from archives created on IBM z/OS using hardware compression tools, changes in FIPS Mode to support NIST algorithm changes affective end of 2010.[18]
  • SecureZIP 14 (released on 2011-10) added support to create and extract OpenPGP files, support for digital time stamping of signed archives, support for processors with AES-NI instruction for faster AES encryption, ability to extract 7-Zip files and CD/DVD Data Image files, new Auto Select View, ability to preserve Zone Identifier information in downloaded files, support to add and extract NTFS alternate streams, added file search logic.
  • SecureZIP and PKZIP 15 for z/OS (released 2013-11-13) added features to expand offloading capabilities for z/OS and mainframe hardware, as well as compression capabilities based on a partnership with IBM.

.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.


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.


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

Other products

PKWARE also used its PKZIP standards on following products:

  • SecureZIP (including SecureZIP PartnerLink)
  • PKZIP Explorer

See also


  1. ^ PKZIP 0.90 review (1989-02-21)
  2. ^ How to Become LZW Free
  3. ^ "comp.compression Frequently Asked Questions (part 1/3)Section - [3] What is the latest PKZIP version?". 
  4. ^ "Malicious Code 101 Definitions and Background". Archived from the original on 22 March 2010. 
  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". ZDNet. 
  9. ^ Bruce Stewart (21 June 2004). "PKWare PKZip for Windows 8.0 review - CNET". CNET. CBS Interactive. 
  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. ^ "PKWARE SecureZIP for Windows Desktop - v11". 
  15. ^ "New version of SecureZip - Security - DSLReports Forums". DSL Reports. 
  16. ^ New SecureZIP for Windows Desktop Brings Public Key Cryptography to Every Type of User
  17. ^ "SecureZIP Standard Edition for Windows Desktop 12.1". PCMAG. 
  18. ^ Matt Little. "Product Updates". 
  19. ^ "comp.compression Frequently Asked Questions (part 1/3)Section - [8] What about patents on data compression algorithms?". 

External links


  • Official website , PKWARE
  • PKZIP 2.50 for DOS
  • SecureZIP from PKWARE


  • SecureZIP Homepage
  • Commentary from SEA owner about Phil Katz, the lawsuit, and his death
    • SEA v. PKWARE and Phil KatzJudgment in favor of SEA in
  • How to Use PKZIP From the Command Line
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.