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Compression and encryption algorithms

 


 

Compression algorithms

Easy Compression Library (ECL) provides 3 main compression algorithms:

  • ZLIB algorithm (modified by Davide Moretti dave@rimini.com)
  • BZIP algorithm (by Julian Seward, jseward@acm.org.)
  • PPM algorithm, variant G (by Dmitry Shkarin, shkarin@arstel.ru)
  •  

    ECL has 3 levels for each of above algorithms: Fastest, Normal and Max.

    Level

    Meaning

    eclNone

     

    No compression

    zlibFastest

    ZLib algorithm, Fastest compression

    zlibNormal

    ZLib algorithm, Normal balance between speed and compression rate

    zlibMax

     

    ZLib algorithm, Maximum compression, rather slow speed

    ppmFastest

    PPM algorithm, Fastest compression

    ppmNormal

    PPM algorithm, Normal balance between speed and compression rate

    ppmMax

     

    PPM algorithm, Maximum compression, rather slow speed

    bzipFastest

    BZIP algorithm, Fastest compression

    bzipNormal

    BZIP algorithm, Normal balance between speed and compression rate

    bzipMax

    BZIP algorithm, Maximum compression, rather slow speed

     

    Typically ZLib is the fastest algorithm, BZIP is fast and has a good rate, PPM provides the maximum rate with rather low speed.

    But it also depends on compression level: i.e. for some files bzipNormal could give you both better compression rate and higher speed than zlibMax.

    So we strongly recommend you to test the above compression levels with your application data, to make an optimal choice.

     

    The most advanced users of ECL editions with source code could also tune the parameters of compression algorithms to achieve the best result for their specific tasks.

     

    Encryption algorithm

    Password protection is provided by the Rijndael encryption algorithm (AES), 128/256 bit key.Hash algorithm is RipeMD-128 / RipeMD-256.

    Implementation of encryption routines is provided by well-known cryptography expert Hagen Reddmann (HaReddmann@AOL.COM), DEC Part I.

    Users of the Pro version can switch between a 128-bit and 256-bit key encryption.

    See Tuning ECL for more details.

     

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