Generate A Random Key In Php

admin

The uniqid( ) function in PHP is an inbuilt function which is used to generate a unique ID based on the current time in microseconds (micro time). By default, it returns a 13 character long unique string. The uniqid( ) function in PHP is an inbuilt function which is used to generate a unique ID based on the current time in microseconds (micro time). By default, it returns a 13 character long unique string. Comcreateguid ( void): string Generates a Globally Unique Identifier (GUID). A GUID is generated in the same way as DCE UUID's, except that the Microsoft convention is to enclose a GUID in curly braces.

  1. Generate A Random Key In Php Word
  2. Php Generate Random Alphanumeric String
  3. Generate A Random Key In Php Pdf

Generate a random number using your favourite random-number generator; Multiply and divide it to get a number matching the number of characters in your code alphabet; Get the item at that index in your code alphabet. Repeat from 1) until you have the length you want; e.g (in pseudo code). This function does not generate cryptographically secure values, and should not be used for cryptographic purposes. If you need a cryptographically secure value, consider using randomint, randombytes, or opensslrandompseudobytes instead. Generate a random number using your favourite random-number generator; Multiply and divide it to get a number matching the number of characters in your code alphabet; Get the item at that index in your code alphabet. Repeat from 1) until you have the length you want; e.g (in pseudo code).

Use the srand() seed '(double)microtime()*1000000' as mentioned by the richard@zend.com at the top of these user notes.
The most notable effect of using any other seed is that your random numbers tend to follow the same, or very similar, sequences each time the script is invoked.
Take note of the following script:
<?php
srand($val);
echo rand(0, 20) . ', ';
echo rand(0, 20) . ', ';
echo rand(0, 20) . ', ';
echo rand(0, 20) . ', ';
echo rand(0, 20);
?>

If you seed the generator with a constant, say; the number 5 ($val = 5), then the sequence generated is always the same, in this case (0, 18, 7, 15, 17) (for me at least, different processors/processor speeds/operating systems/OS releases/PHP releases/webserver software may generate different sequences).
If you seed the generator with time(), then the sequence is more random, but invokations that are very close together will have similar outputs.
As richard@zend.com above suggests, the best seed to use is (double) microtime() * 1000000, as this gives the greatest amount of psuedo-randomness. In fact, it is random enough to suit most users.
In a test program of 100000 random numbers between 1 and 20, the results were fairly balanced, giving an average of 5000 results per number, give or take 100. The deviation in each case varied with each invokation.

This is a short guide on how to generate a random token with PHP. These kind of tokens are used for a number of different reasons:

  • To protect against Cross-Site Request Forgery. These are often referred to as CSRF tokens.
  • To help verify a user’s email address. i.e. You send the user’s email address a link that contains a “random” token in the URL and when they click on it, you compare the token that they’ve given you with the token that you’ve stored against their user account. If the tokens match, you assume that the given email address is correct.
  • To generate a “Forgot Password” request (typically, it uses the same method as the one outlined above).

A lot of people make the mistake of using the function rand or mt_rand in correlation with a hashing function such as md5 or sha1:

The problem with the approach above is that the token will NOT be cryptographically secure.

To generate a cryptographically secure token in PHP, you will need to use the openssl_random_pseudo_bytes function: