I looking for a way, specifically in PHP that I will be guaranteed to always get a unique key.
I have done the following:
strtolower(substr(crypt(time()), 0, 7));
But I have found that once in a while I end up with a duplicate key (rarely, but often enough).
I have also thought of doing:
strtolower(substr(crypt(uniqid(rand(), true)), 0, 7));
But according to the PHP website, uniqid() could, if uniqid() is called twice in the same microsecond, it could generate the same key. I'm thinking that the addition of rand() that it rarely would, but still possible.
After the lines mentioned above I am also remove characters such as L and O so it's less confusing for the user. This maybe part of the cause for the duplicates, but still necessary.
One option I have a thought of is creating a website that will generate the key, storing it in a database, ensuring it's completely unique.
Any other thoughts? Are there any websites out there that already do this that have some kind of API or just return the key. I found http://userident.com but I'm not sure if the keys will be completely unique.
This needs to run in the background without any user input.
I recently wanted a quick and simple random unique key so I did the following:
So, basically, I get the unix time in seconds and add a random md5 string generated from time + random number. It's not the best, but for low frequency requests it is pretty good. It's fast and works.
I did a test where I'd generate thousands of keys and then look for repeats, and having about 800 keys per second there were no repetitions, so not bad. I guess it totally depends on mt_rand()
I use it for a survey tracker where we get a submission rate of about 1000 surveys per minute... so for now (crosses fingers) there are no duplicates. Of course, the rate is not constant (we get the submissions at certain times of the day) so this is not fail proof nor the best solution... the tip is using an incremental value as part of the key (in my case, I used time(), but could be better).