Hello Guy,

Thursday, December 9, 2004, 11:39:27 AM, you wrote:

GB> $hash = md5(uniqid($message));

GB> where message is a string that the user will input.

GB> How likely is it that this hash might be repeated?

GB> I'm using the hash as a primary key in a database - the user gets sent
GB> the hash as part of a url to retrieve the details of that database row.

GB> (its a basic send to a friend e-card system).

GB> Is there any way that the same hash could have been generated more than
GB> once?

It's extremely unlikely (I cannot give you any stats as to how
unlikely though, sorry).

However why not just stick the $hash creation into a self-checking
loop. I.e. make the hash - check the database - does it exist already?
- If not then the hash is good, else repeat the process. Using uniqid
will give you a unique hash on each occasion so this process
shouldn't take very long at all even if it did find a duplicate a few
times (unlikely!)

Best regards,

Richard Davey
-- 
 http://www.launchcode.co.uk - PHP Development Services
 "I am not young enough to know everything." - Oscar Wilde

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