How would it be possible to generate a random, unique string using numbers and letters for use in a verify link? Like when you create an account on a website, and it sends you an email with a link, and you have to click that link in order to verify your account
How can I generate one of those using PHP?
For really random strings, you can use
<?php
echo md5(microtime(true).mt_Rand());
outputs :
40a29479ec808ad4bcff288a48a25d5c
so even if you try to generate string multiple times at exact same time, you will get different output.
This is a simple function that allows you to generate random strings containing Letters and Numbers (alphanumeric). You can also limit the string length. These random strings can be used for various purposes, including: Referral Code, Promotional Code, Coupon Code. Function relies on following PHP functions: base_convert, sha1, uniqid, mt_rand
function random_code($length)
{
return substr(base_convert(sha1(uniqid(mt_rand())), 16, 36), 0, $length);
}
echo random_code(6);
/*sample output
* a7d9e8
* 3klo93
*/
When trying to generate a random password you are trying to :
First generate a cryptographically secure set of random bytes
Second is turning those random bytes into a printable string
Now, there are multiple way to generate random bytes in php like :
$length = 32;
//PHP 7+
$bytes= random_bytes($length);
//PHP < 7
$bytes= openssl_random_pseudo_bytes($length);
Then you want to turn these random bytes into a printable string :
You can use bin2hex :
$string = bin2hex($bytes);
or base64_encode :
$string = base64_encode($bytes);
However, note that you do not control the length of the string if you use base64. You can use bin2hex to do that, using 32 bytes will turn into a 64 char string. But it will only work like so in an EVEN string.
So basically you can just do :
$length = 32;
if(PHP_VERSION>=7){
$bytes= random_bytes($length);
}else{
$bytes= openssl_random_pseudo_bytes($length);
}
$string = bin2hex($bytes);
This people choking on a glass of water...
$random= substr(str_shuffle("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ*.-_"), 0, 10);
Simple. The posibility to this random string repeat is 0,000000000000000000000000000001^70
If you want to generate a unique string in PHP, try following.
md5(uniqid().mt_rand());
In this,
uniqid() - It will generate unique string. This function returns timestamp based unique identifier as a string.
mt_rand() - Generate random number.
md5() - It will generate the hash string.
Simple 'one line' string hash generator like
77zd43-7bc495-64cg9a-535548 (1byte = 2chars)
$hash = implode('-', [
bin2hex(random_bytes(3)),
bin2hex(random_bytes(3)),
bin2hex(random_bytes(3)),
bin2hex(random_bytes(3)),
]);
I always use this my function to generate a custom random alphanumeric string... Hope this help.
<?php
function random_alphanumeric($length) {
$chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ12345689';
$my_string = '';
for ($i = 0; $i < $length; $i++) {
$pos = mt_rand(0, strlen($chars) -1);
$my_string .= substr($chars, $pos, 1);
}
return $my_string;
}
echo random_alphanumeric(50); // 50 characters
?>
It generates for example: Y1FypdjVbFCFK6Gh9FDJpe6dciwJEfV6MQGpJqAfuijaYSZ86g
If you want compare with another string to be sure that is a unique sequence you can use this trick...
$string_1 = random_alphanumeric(50);
$string_2 = random_alphanumeric(50);
while ($string_1 == $string_2) {
$string_1 = random_alphanumeric(50);
$string_2 = random_alphanumeric(50);
if ($string_1 != $string_2) {
break;
}
}
echo $string_1;
echo "<br>\n";
echo $string_2;
it generate two unique strings:
qsBDs4JOoVRfFxyLAOGECYIsWvpcpMzAO9pypwxsqPKeAmYLOi
Ti3kE1WfGgTNxQVXtbNNbhhvvapnaUfGMVJecHkUjHbuCb85pF
Hope this is what you are looking for...
A simple solution is to convert base 64 to alphanumeric by discarding the non-alphanumeric characters.
This one uses random_bytes() for a cryptographically secure result.
function random_alphanumeric(int $length): string
{
$result='';
do
{
//Base 64 produces 4 characters for each 3 bytes, so most times this will give enough bytes in a single pass
$bytes=random_bytes(($length+3-strlen($result))*2);
//Discard non-alhpanumeric characters
$result.=str_replace(['/','+','='],['','',''],base64_encode($bytes));
//Keep adding characters until the string is long enough
//Add a few extra because the last 2 or 3 characters of a base 64 string tend to be less diverse
}while(strlen($result)<$length+3);
return substr($result,0,$length);
}
Edit: I just revisited this because I need something a bit more flexible. Here is a solution that performs a bit better than the above and gives the option to specify any subset of the ASCII character set:
<?php
class RandomText
{
protected
$allowedChars,
//Maximum index to use
$allowedCount,
//Index values will be taken from a pool of this size
//It is a power of 2 to keep the distribution of values even
$distributionSize,
//This many characters will be generated for each output character
$ratio;
/**
* @param string $allowedChars characters to choose from
*/
public function __construct(string $allowedChars)
{
$this->allowedCount = strlen($allowedChars);
if($this->allowedCount < 1 || $this->allowedCount > 256) throw new \Exception('At least 1 and no more than 256 allowed character(s) must be specified.');
$this->allowedChars = $allowedChars;
//Find the power of 2 equal or greater than the number of allowed characters
$this->distributionSize = pow(2,ceil(log($this->allowedCount, 2)));
//Generating random bytes is the expensive part of this algorithm
//In most cases some will be wasted so it is helpful to produce some extras, but not too many
//On average, this is how many characters needed to produce 1 character in the allowed set
//50% of the time, more characters will be needed. My tests have shown this to perform well.
$this->ratio = $this->distributionSize / $this->allowedCount;
}
/**
* @param int $length string length of required result
* @return string random text
*/
public function get(int $length) : string
{
if($length < 1) throw new \Exception('$length must be >= 1.');
$result = '';
//Keep track of result length to prevent having to compute strlen()
$l = 0;
$indices = null;
$i = null;
do
{
//Bytes will be used to index the character set. Convert to integers.
$indices = unpack('C*', random_bytes(ceil(($length - $l) * $this->ratio)));
foreach($indices as $i)
{
//Reduce to the smallest range that gives an even distribution
$i %= $this->distributionSize;
//If the index is within the range of characters, add one char to the string
if($i < $this->allowedCount)
{
$l++;
$result .= $this->allowedChars[$i];
}
if($l >= $length) break;
}
}while($l < $length);
return $result;
}
}
one can use this code. i tested with 35,000,00 IDs no duplicates.
<?php
$characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_';
$result = '';
for ($i = 0; $i < 11; $i++)
$result .= $characters[mt_rand(0, 63)];?>
you are free to modify it as your need. and if you have any suggestions feel free to comment.it is recommended that you should check every id in your database before using this ids by doing that you have 100% unique ids in your database.
we can use this two line of code to generate unique string have tested around 10000000 times of iteration
$sffledStr= str_shuffle('abscdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()_-+');
$uniqueString = md5(time().$sffledStr);
Here is a fun one
public function randomStr($length = 16) {
$string = '';
while (($len = strlen($string)) < $length) {
$size = $length - $len;
$bytes = random_bytes($size);
$string .= substr(str_replace(['/', '+', '='], '', base64_encode($bytes)), 0, $size);
}
return $string;
}
Stolen from laravel here
function codeGenerate() {
$randCode = (string)mt_rand(1000,9999);
$randChar = rand(65,90);
$randInx = rand(0,3);
$randCode[$randInx] = chr($randChar);
return $randCode;
}
echo codeGenerate();
OUTPUT
38I7
33V7
E836
736U