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Re: get hexadecimal hash string for a number

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On Tue, 18 Sep 2012 18:25:12 +0200, Magnus Warker
<magnux@mailinator.com> wrote:

>Hi,
>
>I want users to register on a site and send confirmation emails to them. 
>These emails should contain a link like this:
>
>http://myurl?registration=E4AC4BD4
>
>Here, "E4AC4BD4" should be a unique string. My idea for such a string is 
>just to hash an integer, i. e. the internal database key for the 
>registration record.
>
>However, I actually don't know how to get such a hash. I tried BCrypt, 
>but this produces hashes built out of characters that I would not want 
>to be in a URL, e. g. commatas and that.
>
>I would like to have a string like this:
>
>- hexadecimal only
>- fixed size, e. g. always n characters, independend of the integer
>
>Can you help?
>
>Thank you!
>
>Magnus
As has been pointed out, integers are already unique.  Just decide on
a large enough fixed size and zero pad the small numbers:
0000000000001

If you want to disguise the actual number you are using, which is what
I take your mention of "hash" to mean, then you need an encryption.
Each unique input gives a unique output.  It has to be unique,
otherwise you couldn't decrypt it reliably.

For 64 bit numbers, just use DES and encrypt the numbers 0, 1, 2, 3,
... n in turn.  For 128 bits use AES.

If you want to use a size other than 64 or 128 bits then have a look
at Hasty Pudding cypher, which can be set for any desired bit size.

Again, you will need to be sure that your chosen bit size will
acommodate enough users, with plenty to spare for keeping the gaps
numerous enough.

rossum

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Thread

get hexadecimal hash string for a number Magnus Warker <magnux@mailinator.com> - 2012-09-18 18:25 +0200
  Re: get hexadecimal hash string for a number markspace <-@.> - 2012-09-18 10:08 -0700
    Re: get hexadecimal hash string for a number Lew <lewbloch@gmail.com> - 2012-09-18 10:14 -0700
    Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-18 19:58 -0400
      Re: get hexadecimal hash string for a number markspace <-@.> - 2012-09-18 17:27 -0700
        Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-18 21:17 -0400
        Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-18 21:21 -0400
      Re: get hexadecimal hash string for a number Magnus Warker <warker@mailinator.com> - 2012-09-19 08:27 +0200
        Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-19 18:30 -0400
        Re: get hexadecimal hash string for a number Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2012-09-19 19:06 -0700
          Re: get hexadecimal hash string for a number Magnus Warker <warker@mailinator.com> - 2012-09-20 11:32 +0200
  Re: get hexadecimal hash string for a number Lew <lewbloch@gmail.com> - 2012-09-18 10:10 -0700
    Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-18 20:02 -0400
    Re: get hexadecimal hash string for a number Magnus Warker <warker@mailinator.com> - 2012-09-19 08:18 +0200
  Re: get hexadecimal hash string for a number Roedy Green <see_website@mindprod.com.invalid> - 2012-09-18 10:23 -0700
    Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-18 20:00 -0400
  Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-18 20:06 -0400
    Re: get hexadecimal hash string for a number markspace <-@.> - 2012-09-18 17:30 -0700
      Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-18 21:07 -0400
  Re: get hexadecimal hash string for a number Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2012-09-18 22:50 -0700
  Re: get hexadecimal hash string for a number Leif Roar Moldskred <leifm@dimnakorr.com> - 2012-09-19 01:06 -0500
  Re: get hexadecimal hash string for a number rossum <rossum48@coldmail.com> - 2012-09-19 17:34 +0100
    Re: get hexadecimal hash string for a number Magnus Warker <warker@mailinator.com> - 2012-09-20 11:30 +0200
      Re: get hexadecimal hash string for a number rossum <rossum48@coldmail.com> - 2012-09-21 12:48 +0100
        Re: get hexadecimal hash string for a number Lew <lewbloch@gmail.com> - 2012-09-21 10:15 -0700
          Re: get hexadecimal hash string for a number Magnus Warker <warker@mailinator.com> - 2012-09-26 06:11 +0200
            Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-26 09:29 -0400
              Re: get hexadecimal hash string for a number Gene Wirchenko <genew@ocis.net> - 2012-09-26 09:18 -0700
      Re: get hexadecimal hash string for a number markspace <-@.> - 2012-09-21 10:56 -0700
        Re: get hexadecimal hash string for a number Magnus Warker <warker@mailinator.com> - 2012-09-26 06:12 +0200
      Re: get hexadecimal hash string for a number Arne Vajhøj <arne@vajhoej.dk> - 2012-09-23 20:57 -0400

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