Results 1 to 7 of 7

Thread: Hash Zip

  1. #1
    Member
    Join Date
    Dec 2006
    Posts
    611
    Thanks
    0
    Thanked 1 Time in 1 Post
    I came over interesting compression program called Hash Zip. The most recent version divides file targeted for compression into 256-byte chunks, computes SHA hash of each chunk and stores some statistics about each one. Author claims that each chunk is compressed to 30 bytes (I'm aware that this could result in lossy compression, but I want to try it anyway).

    However, I am not able to compile its sources, could someone compile them please? There are all three versions in the archive.
    Hash Zip sources

  2. #2
    The Founder encode's Avatar
    Join Date
    May 2006
    Location
    Moscow, Russia
    Posts
    3,982
    Thanks
    377
    Thanked 351 Times in 139 Posts
    I also had problems with compiling under win32.

    Anyway, I think even if this program works correctly, it must show extremely slow decompression speed...

    In other words, this is a Bullshit & co.


  3. #3
    Member
    Join Date
    Dec 2006
    Posts
    611
    Thanks
    0
    Thanked 1 Time in 1 Post
    Quote Originally Posted by author
    string abcde
    v0.1 Total hash calls for block 1: 5746167
    85.98s real 41.78s user 0.01s system
    v0.2 Total hash calls for block 1: 4460925
    105.59s real 49.71s user 0.00s system
    If hes brute-forcing SHA hashes, then it is first "compressor", which has compression speed marginally higher than decompression speed

  4. #4
    The Founder encode's Avatar
    Join Date
    May 2006
    Location
    Moscow, Russia
    Posts
    3,982
    Thanks
    377
    Thanked 351 Times in 139 Posts
    A la CRC32 zip. A file can be compressed to eight bytes (four bytes for uncompressed size, plus four bytes for checksum). It will be pretty cool - just compress any mp3 song to eight bytes... How much music I can store on my 200 GB HDD when. One problem, how to get the original data back...

    Even brute-force password cracking tooks forever, and it's about only 8-12 symbols. Imagine now 5 MB at least...

  5. #5
    Member
    Join Date
    Dec 2006
    Posts
    611
    Thanks
    0
    Thanked 1 Time in 1 Post
    Quote Originally Posted by encode
    Even brute-force password cracking tooks forever, and its about only 8-12 symbols. Imagine now 5 MB at least...
    Depends, how effectively are those "statistics bytes" used, but I agree they will tighten the decompression times mostly, like, from ten bilion years to hundred milion years

    Quote Originally Posted by encode
    this is a Bullshit & co
    Author replied me in a very similar manner. I just wonder why is he offering the sources then

  6. #6
    The Founder encode's Avatar
    Join Date
    May 2006
    Location
    Moscow, Russia
    Posts
    3,982
    Thanks
    377
    Thanked 351 Times in 139 Posts
    I think the author wanted to make some noise around the web. Just created super-compressor with super newly invented and revolutionary compression...

  7. #7
    Programmer
    Join Date
    Feb 2007
    Location
    Germany
    Posts
    420
    Thanks
    28
    Thanked 153 Times in 18 Posts
    Quote Originally Posted by Black_Fox
    The most recent version divides file targeted for compression into 256-byte chunks, computes SHA hash of each chunk and stores some statistics about each one.
    Just assume itd be possible to find a collision for a cryptographic hash-function in a reasonable amount of time. Even under this purely hypothetical assumption there wouldnt be any guarantee that the collision represents the original data... bijective function anyone?
    I do NOT want to badmouth the author - but at least hes a funny guy.

Similar Threads

  1. QuickLZ ZIP - new zip/deflate library
    By Lasse Reinhold in forum Forum Archive
    Replies: 23
    Last Post: 1st October 2007, 23:08

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •