Rails - Feb 2006 - Creating a String of Random Characters and Numbers

I want to create a random string of length n that is made up of  
characters and integers.  Is there a function in rails or ruby that  
allows me to do this?

Thank you my friend :-).

John Kopanas
http://www.kopanas.com


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How about md5?  It''s possibly not ideal, but it is very simple to use

It generates strings of (I think) 40 characters in length, when you
give it a string to encrypt.  For an (random) string to encrypt, you
could e.g. concatenate the MAC address of your LAN card with the
current date and time from Time.now.  md5 works on a one-way hash
algorithm, so it''s (practically) impossible to start with the
generated md5 string and work backwards to get the string you
originally encrypted.

If 40 characters is too long, just truncate it.

Would that suit?

Sample use:
require ''md5''
md5_string = MD5.md5(''random string to encrypt'').hexdigest
print md5_string      # <<<--- should give you 40 pseudo-random
characters

Regards

Dave M

On 14/02/06, John Kopanas <john@protoseinc.com>
wrote:
> I want to create a random string of length n that is made up of
> characters and integers.  Is there a function in rails or ruby that
> allows me to do this?
>
> Thank you my friend :-).
>
> John Kopanas
> http://www.kopanas.com
>
>
> ====================================================================>
http://www.soen.info - source of the freshest software engineering
> information on the net
> http://cusec.soen.info - software engineering conference
>
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

On Mon, Feb 13, 2006 at 07:36:54PM -0500, John Kopanas wrote:
} I want to create a random string of length n that is made up of  
} characters and integers.  Is there a function in rails or ruby that  
} allows me to do this?

def randStr(len)
  (1..len).inject("") { |s, x| s << rand(128) }
end

} Thank you my friend :-).
} John Kopanas
--Greg

md5 seems like overkill, and you still have to generate a random  
string to give to it anyway!

Here''s what I do in some of my code:

   token_chars  = (''a''..''z'').to_a +
(''A''..''Z'').to_a +
(''0''..''9'').to_a
   token_length = 10

   Array.new(token_length) { token_chars[rand 
(token_chars.length)] }.join


Cheers,

Pete Yandell

On Mon, Feb 13, 2006 at 08:16:46PM -0500, Gregory Seidman wrote:
} On Mon, Feb 13, 2006 at 07:36:54PM -0500, John Kopanas wrote:
} } I want to create a random string of length n that is made up of  
} } characters and integers.  Is there a function in rails or ruby that  
} } allows me to do this?
} 
} def randStr(len)
}   (1..len).inject("") { |s, x| s << rand(128) }
} end

Sorry to respond to my own post, but it looks like you wanted
alphanumerics. Try this instead (I also changed the method name to follow
Ruby conventions):

def rand_str(len, domain)
  (1..len).inject("") { |s, x| s << domain[rand(domain.length)]
}
end

You can then call it as:

alphanum = [ (''a''..''z'').to_a,
(''A''..''Z'').to_a,
(''0''..''9'').to_a ].flatten
rand_str(10, alphanum)

} } Thank you my friend :-).
} } John Kopanas
--Greg

John Kopanas wrote:
> I want to create a random string of length n that is made up of
> characters and integers.  Is there a function in rails or ruby that
> allows me to do this?
> 
> Thank you my friend :-).
> 
> John Kopanas
> http://www.kopanas.com
Here''s what I do to generate a "ticket" number for web
access.

val = Integer(''0x'' +
Digest::SHA1.hexdigest("#{Time.now.to_f}#{rand}"))

Get the time and salt it with a random number.  The time can be the same 
between successive calls.  You can also do some fun stuff with rand to 
get better randoms.  Depends on how secure you need it to be.

Then you can convert to alphanumeric using the other suggestions on this 
thread.

   Jake


-- 
Posted via http://www.ruby-forum.com/.

So many have already given their opinion, but here''s another (mine, of
course).
This came out of an ActiveRecord model that wants to create an 
attribute that is "just random enough" not to conflict with other 
records.  It''s meant to be typed so the letters I (eye) and O (oh) 
are avoided since they might easily be mistaken for 1 (one) and 0 (zero).

It should probably not recompute the letterset each call and I''ve so 
far avoided trying to guarantee that it will be unique among all 
other records (the begin...end while() part)

It may not be what you need, but it may give you ideas.

-Rob


   def password
     read_attribute(:password) ||
       write_attribute(:password, self.class.new_password)
   end

   def self.new_password
     # generate an 8-character "password" intended to be unique
     # about 40% digits from 0..9
     # rest from letters A..H, J..N, P..Z
     digitpct = 0.4
     letterset =  (''A''..''Z'').to_a -
[''I'', ''O'']
     #begin
     passwd = ''''
     8.times do
       if rand < digitpct
         passwd << rand(10).to_s
       else
         passwd << letterset[rand(letterset.length)]
       end
     end
     #end while (self.find_by_password(passwd))
     passwd
   end


At 2/13/2006 07:36 PM, John Kopanas wrote:
>I want to create a random string of length n that is made up of
>characters and integers.  Is there a function in rails or ruby that
>allows me to do this?
>
>Thank you my friend :-).
>
>John Kopanas
>http://www.kopanas.com
>
>====================================================================>http://www.soen.info
- source of the freshest software engineering
>information on the net
>http://cusec.soen.info - software engineering conference
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