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7-Zip method IDs for 7z and xz archives

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Version: 15.06

Date: 2015-06-23



Each compression or crypto method in 7z is associated with unique binary value (ID).

The length of ID in bytes is arbitrary but it can not exceed 63 bits (8 bytes).



xz and 7z formats use same ID map.



If you want to add some new ID, you have two ways:

  1) Write request for allocating IDs to 7-Zip developers.

  2) Generate 8-bytes ID:



    3F ZZ ZZ ZZ ZZ ZZ MM MM 



    3F              - Prefix for random IDs (1 byte)

    ZZ ZZ ZZ ZZ ZZ  - Developer ID (5 bytes). Use real random bytes. 

                      

    MM MM           - Method ID (2 bytes)



    You can notify 7-Zip developers about your Developer ID / Method ID.



    Note: Use new ID, if old codec can not decode data encoded with new version.





List of defined IDs

-------------------

      

00 - Copy



03 - Delta

04 - BCJ (x86)

05 - PPC (big-endian)

06 - IA64

07 - ARM (little-endian)

08 - ARMT (little-endian)

09 - SPARC



21 - LZMA2

          

02.. - Common

   03 [Swap]

      - 2 Swap2

      - 4 Swap4



03.. - 7z

   01 - 

      01 - LZMA

  

   03 - [Branch Codecs]

      01 - [x86 Codecs]

         03  - BCJ

         1B  - BCJ2 (4 packed streams)

      02 - 

         05 - PPC (big-endian)

      03 - 

         01 - Alpha

      04 - 

         01 - IA64

      05 - 

         01 - ARM (little-endian)

      06 - 

         05 - M68 (big-endian)

      07 - 

         01 - ARMT (little-endian)

      08 - 

         05 - SPARC



   04 - 

      01 - PPMD



   7F -

      01 - experimental method.





04.. - Misc codecs



   00 - Reserved



   01 - [Zip]

      00 - Copy (not used. Use {00} instead)

      01 - Shrink

      06 - Implode

      08 - Deflate

      09 - Deflate64

      0A - Imploding

      0C - BZip2 (not used. Use {040202} instead)

      0E - LZMA (LZMA-zip)

      5F - xz

      60 - Jpeg

      61 - WavPack

      62 - PPMd (PPMd-zip)

      63 - wzAES



   02 - 

      02 - BZip2



   03 - [Rar]

      01 - Rar1

      02 - Rar2

      03 - Rar3

      05 - Rar5



   04 - [Arj]

      01 - Arj(1,2,3)

      02 - Arj4



   05 - [Z]



   06 - [Lzh]



   07 - Reserved for 7z



   08 - [Cab]



   09 - [NSIS]

      01 - DeflateNSIS

      02 - BZip2NSIS



   F7 - External codecs (that are not included to 7-Zip)



      0x xx - reserved

      10 xx - reserved





06.. - Crypto 



   F0 - Ciphers without hashing algo



      01 - [AES]

         0x - AES-128

         4x - AES-192

         8x - AES-256

         Cx - AES



         x0 - ECB

         x1 - CBC

         x2 - CFB

         x3 - OFB

         x4 - CTR



   F1 - Combine Ciphers



      01 - [Zip]

         01 - ZipCrypto (Main Zip crypto algo)



      03 - [RAR]

         02 - 

         03 - Rar29AES (AES-128 + modified SHA-1)



      07 - [7z]

         01 - 7zAES (AES-256 + SHA-256)





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