Comments on: PHP Unique Hash

By: Alec Gorge

Alec Gorge — Mon, 19 Sep 2011 21:54:16 +0000

Kevin,

Great algorithm! I wanted to use it in my upcoming Node.js project, so I made a CommonJS/Node.js module available here: https://github.com/alecgorge/node-psuedohash

Thanks again for putting this together!

By: KevBurnsJr

KevBurnsJr — Sat, 07 May 2011 06:30:26 +0000

Using time() would probably not be a good idea, just because there’s a good chance that two records may be created within the same second.

What I usually do instead for keys is

echo time().’-’.base_convert(rand(1,getrandmax()), 10, 36);

which yields a key like 1304134276-udxxi7

By: Jenny

Jenny — Fri, 06 May 2011 14:52:45 +0000

Me again :)
I wanted to know if you think it would be safe to run this command instead of your look.

echo PseudoCrypt::udihash(time());

I’m trying to create unique HASH to be inserted as KEY on database, but generating your way the hash always stays the same.

Please let me know if there is any draw back to this solution.

Thank you!

Jenny

By: Jenny

Jenny — Fri, 06 May 2011 14:10:35 +0000

How many total “unique” possibilities are we talking about here?

By: John

John — Tue, 29 Mar 2011 02:49:10 +0000

Hi, I implemented this in Factor, if you’re curious:

http://re-factor.blogspot.com/2011/03/unique-hash.html

By: KevBurnsJr

KevBurnsJr — Mon, 28 Mar 2011 10:28:37 +0000

10 is probably too large. I suggest you run it w/ 5 or 6 and append some random data.

$hash = PseudoCrypt::udihash($id, 5);
$rand = PseudoCrypt::base62(rand(0,pow(62,5)));
$rand = str_pad($rand, 5, “0″, STR_PAD_LEFT);
$key = $hash.$rand;

By: Druczki Pocztowe

Druczki Pocztowe — Mon, 28 Mar 2011 10:19:22 +0000

Try rining the script with: PseudoCrypt::udihash($id, 10)

All keys wil have values:
000000000000
000000000000
000000000000
000000000000
000000000000
000000000000
000000000000
000000000000
000000000000
000000000000

How to solve it?

By: Warren Wilkinson

Warren Wilkinson — Fri, 18 Mar 2011 04:31:46 +0000

Hey German, if you want decodable ones — would printing random numbers in base 64 work? Most languages let you print in base 16 (hex) and usually (with some sleuthing) have ways to read/write base 64.

By: Morteza

Morteza — Tue, 06 Jul 2010 17:40:46 +0000

Hey, that’s very useful!! I wanted to use unique IDs to generate a code as password for my users so they can come back later on the site, and enter this code, so they can edit what they entered. your algorithm is useful in my case.

thank you.

@Tim: I think, not needing the inverse function, it is not important to have different values for one number.

By: Tim

Tim — Thu, 01 Apr 2010 21:30:20 +0000

Wonderful function — but the output diverges above 58 on two systems I’m testing on. I suspect it’s because one’s a 32bit machine, and the other 64.

Any thoughts on a fix for that?

If I find one, I’ll come back and post.