Beefy Boxes and Bandwidth Generously Provided by pair Networks
Problems? Is your data what you think it is?
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

BrowserUk,

This is an observation sometime from 2005-2008. My handle on PM is because of working on this project at the time I joined, but I have little to due with the project now. It was a project to backup Terabytes of encrypted files to geographically distant off-site computer centers using 'rsync' in close to 'real-time'. The client's goal was that 'rsync' not work with the real files, but only with encrypted files which sort of negates the value of using 'rsync'. While we looked at several methods for getting a value for naming the encrypted files, we ran tests of several different sets of 1 million encrypted files and the following table is an average.

Technique Duplicates MD5 5,701 crc32 26,323 SimCRC64 17 Simple 8 byte ^ of file (very fast +)

I can't say these results would be the same anywhere else, but when I started testing, I was sure that MD5 would be the most unique, and that's why we ran the tests several times with different file sets. I don't know if the encryption algorithm affected the results and don't know it the unencrypted files would give similiar results or not. I just didn't expect the results!

I only bring this up because I think you started out with the same assumption about MD5, but maybe there is a better starting point and maybe not.

Thank you

"Well done is better than well said." - Benjamin Franklin


In reply to Re: [OT] The statistics of hashing. by flexvault
in thread [OT] The statistics of hashing. by BrowserUk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others exploiting the Monastery: (7)
    As of 2020-08-14 15:20 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?
      Which rocket would you take to Mars?










      Results (76 votes). Check out past polls.

      Notices?