PKLITE

PKLITE is an executable compression utility, from the makers of PKZIP (see ZIP). There was a free-for-noncommercial-use version, and a "Professional" version. There was a separate PKLITE32 product for 32-bit Windows.

It supports mainly DOS .EXE and .COM formats. Version 2.01 added the ability to compress Windows 3.x executables.

Many files compressed by PKLITE can be decompressed by PKLITE, using the  option. The main exception is files compressed with, an option only available in the Professional version.

Version number
For pristine PKLITE-compressed EXE files, the 16-bit little-endian integer at offset 28 characterizes, in broad terms, the version of PKLITE that was used, and the type of compression. The low 12 bits are the version number; for example, 0x10f means version 1.15. The 0x1000 bit is set if "extra" compression was used. The 0x2000 bit is another compression setting.

Version 1.20
There was no free v1.20 release, but legitimate files do exist with that version number. Most of them are self-extracting ZIP files made by PKZIP v2.04's ZIP2EXE utility.

There is also a fake version that claims to be v1.20, but is actually a hacked copy of v1.12 Professional. The files it creates are (correctly) labeled as v1.12.

Identification
Robust identification of PKLITE-compressed files is challenging, due to the many versions and options, and the fact that PKLITE files were often modified to make them more difficult to identify and/or decompress.

Note that PKLITE includes CHK4LITE, a utility that tries to identify PKLITE-compressed files, and the version of PKLITE they were created with. Different versions of CHK4LITE work differently, but it is fairly rudimentary, and never stood much chance in the arms race over disguising PKLITE files.

Identification of DOS COM
Based on the start of the copyright message near the beginning of the file...


 * v1.00β has "" at offset 38.
 * v1.00 has "" at offset 44.
 * v1.03-1.14 has "" at offset 44.
 * v1.15-2.01 has "" at offset 46.

Identification of DOS EXE
There is a copyright message at offset 30 that starts with "" (v2.01) or "" (all other versions).

It's likely that all files (except those from v1.00β) have bytes or  at offset 6, and  at offset 20 (refer to MS-DOS EXE). This is fairly distinctive, though false positives are possible.

Identification of Windows EXE
There is a copyright message at offset 66 that starts with "".

Specifications

 * ModdingWiki: PKLite
 * PKLITE V1.12 compression format

Software

 * PKLITE freeware/shareware, for DOS
 * (1990-12-01)
 * (1990-12-20)
 * (1991-03-20)
 * (1991-06-15)
 * (1991-08-01)
 * (1992-06-01)
 * (1992-07-30)
 * (1995-04-10)
 * (1996-03-15)
 * PKLITE - other/various
 * PKLite at old-dos.ru - various versions
 * (1990-05-29) (not an authorized release)
 * fake v1.20 (1992-08-20): [], ,
 * XADIP201.ZIP (at vetusware.com) - Hacked "XADi" version of PKLITE 2.01-shareware. Claims to support the  option, but it only does a little of what the real software does.

Decompression, general:
 * depklite (Not a complete decompression utility, but maybe useful.)
 * mz-explode
 * (with  option)

Decompression, for DOS:
 * PKLITE (with  option)
 * DISLITE by JohnPC & CV-Tassle: · another copy · source code
 * See Executable compression for some multi-format utilities that support PKLITE, e.g. UNP.
 * UnPKLite (archived) by Tenth Planet Software / Clive Turvey
 * by Montgomery Engineering
 * by The Software Surgeon & Electronic Rats
 * Universal PKLITE Unpacker (UNPKLITE.EXE) by PReDaTor 666: → Executable Tools Pack → unpackers/universal pklite unpacker.*
 * AVPACK
 * by Inbar Raz (COM files only, includes source code)

Protectors (utilities that modify a PKLITE-compressed file to make it more difficult to identify and/or decompress):
 * (requires BRUN45.EXE, not included)
 * [ UN²PACK v2.0]
 * [ UN²PACK v2.0]

Other:
 * - Patches v1.00-1.05 to fix bugs, and changes the version number to 1.06.
 * See also MEGALITE
 * See also PKTINY

Sample files

 * https://github.com/camoto-project/testexe/tree/master/compress

Links

 * Archived copy of PKLITE web page