Microsoft KWAJ installation compression

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File Format
Name Microsoft KWAJ installation compression
Ontology
Extension(s) .??_, .??$
PRONOM fmt/469
Wikidata ID Q105850885

Microsoft KWAJ installation compression refers to a compressed file format used for software installation by Microsoft and their installer tools. "KWAJ" refers to the signature bytes at the beginning of a compressed file.

KWAJ is a relative of some similar formats, most importantly the one known as "SZDD". For the other formats, see MS-DOS installation compression and Microsoft SZ installation compression.

KWAJ is more sophisticated than SZDD, though the relationship between them is not clear.

Contents

Format details

There is a 16-bit field at offset 8 that specifies the compression or encoding method.

Compression code Description
0 Uncompressed (rare)
1 XOR (rare)
2 Okumura's LZSS
3 LZ77 + Huffman
4 MSZIP (based on DEFLATE)

Identification

Files begin with bytes 4b 57 41 4a 88 f0 27 d1.

Specifications

Software

  • MSDN Library - April 1996 → MSDN15_1.iso → MSDNSMPL/PROD/EISPAK11/DECOMP.EXE - Decompression utility for DOS; supports compression methods 2, 3, 4
  • libmspack → msexpand (decompress only)
  • Deark

See also MS-DOS installation compression#Software.

Sample files

Compression method 2:

Compression method 3:

Compression method 4:

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