How to generate random password with PHP?

here is a function that generates a password with a minimum length, a minimum number of digits and a minimal number of letters.

function generatePassword() {
$min_length=8;  //Minimum length of the password
$min_numbers=2; //Minimum of numbers AND special characters
$min_letters=2; //Minimum of letters

$password = '';
$numbers=0;
$letters=0;
$length=0;

while ( $length <= $min_length OR $numbers <= $min_numbers OR $letters <= $min_letters) {
    $length+=1;
    $type=rand(1, 3);
    if ($type==1) {
        $password .= chr(rand(33, 64)); //Numbers and special characters
        $numbers+=1;
    }elseif ($type==2) {
        $password .= chr(rand(65, 90)); //A->Z
        $letters+=1;
    }else {
        $password .= chr(rand(97, 122)); //a->z
        $letters+=1;
    }

}
return $password;   
}

Another, very simple (and secure!) way to do this is the following (I generate all my own passwords that way):

base64_encode(random_bytes(12));

This generates a 16 character password that uses quite a sane range of characters.

However, depending on your requirements (for example if a user needs to type in their password), it may be desirable to remove characters that migth be confused (such as l, I, 1, 0, O, 5, S, and so on). In that case, the above solution is probably a bit too simple.

function generate_password($length = 6) {
    $password = '';
    $chars = array_merge(range('a', 'z'), range('A', 'Z'), range(0, 9));
    for ($i = 0; $i < $length; $i ++) {
        $password .= $chars[array_rand($chars)];
    }
    return $password;
}

This function will include half digits and half numbers:

     function generateMixedPassword($length = 8) {
        $base = 'abcdefghijklmnopqrstuvwxyz';
        $baseD = '0123456789';

        $r = array();

        for ($i = 0; $i < $length; $i += 2) {
            $r[] = substr($base, rand(0, strlen($base) - 1), 1);
        }
        for ($i = 0; $i < $length; $i += 2) {
            $r[] = substr($baseD, rand(0, strlen($baseD) - 1), 1);
        }
        shuffle($r);

        return implode('', $r);
    }

Using the same login, it can be extended to also include special characters

This function will generate more stronger password than most woted solution:

function generatePassword($size=8){
    $p = openssl_random_pseudo_bytes(ceil($size*0.67), $crypto_strong);
    $p = str_replace('=', '', base64_encode($p));
    $p = strtr($p, '+/', '^*');
    return substr($p, 0, $size);      
}

Each character of password will be [A-Z] or [a-z] or ^ or *

use hackzilla/password-generator

it has many options to create different kind of passwords:

• ComputerPasswordGenerator()
• HybridPasswordGenerator() -> sjgX-PFjH-zxMz-PRDz-G6mx-wMJ4-ST24
• HumanPasswordGenerator() -> Verkuemmerungen-verlottertet-dreinzuschauen (word list based. in this case a german word list)
• RequirementPasswordGenerator()

ComputerPasswordGenerator

$generator
  ->setOptionValue(ComputerPasswordGenerator::OPTION_UPPER_CASE, true)
  ->setOptionValue(ComputerPasswordGenerator::OPTION_LOWER_CASE, true)
  ->setOptionValue(ComputerPasswordGenerator::OPTION_NUMBERS, true)
  ->setOptionValue(ComputerPasswordGenerator::OPTION_SYMBOLS, false)
;

$password = $generator->generatePassword();

RequirementPasswordGenerator

$generator
  ->setLength(16)
  ->setOptionValue(RequirementPasswordGenerator::OPTION_UPPER_CASE, true)
  ->setOptionValue(RequirementPasswordGenerator::OPTION_LOWER_CASE, true)
  ->setOptionValue(RequirementPasswordGenerator::OPTION_NUMBERS, true)
  ->setOptionValue(RequirementPasswordGenerator::OPTION_SYMBOLS, true)
  ->setMinimumCount(RequirementPasswordGenerator::OPTION_UPPER_CASE, 2)
  ->setMinimumCount(RequirementPasswordGenerator::OPTION_LOWER_CASE, 2)
  ->setMinimumCount(RequirementPasswordGenerator::OPTION_NUMBERS, 2)
  ->setMinimumCount(RequirementPasswordGenerator::OPTION_SYMBOLS, 2)
  ->setMaximumCount(RequirementPasswordGenerator::OPTION_UPPER_CASE, 8)
  ->setMaximumCount(RequirementPasswordGenerator::OPTION_LOWER_CASE, 8)
  ->setMaximumCount(RequirementPasswordGenerator::OPTION_NUMBERS, 8)
  ->setMaximumCount(RequirementPasswordGenerator::OPTION_SYMBOLS, 8)
;

$password = $generator->generatePassword();

I use st_split and implode function:

function genarateKey(){
    $limit= 8;
    $chars= 'abcdefghijklmnopqrstuvxwyz1234567890!@#$%^&*()_+=-[]{}\|ABCDEFGHIJKLMNOPQRSTUVXWYZ';
    $chararray= str_split($chars);
    $gen=array();
    for($i=0;$i<$limit;$i++){
        $index=rand(0,strlen($chars)-1);
        $gen[$i]= $chararray[$index];
    }
    return implode($gen); //converts array to string
}

Memorable password generator

function password($length)
  {
    $vowel = array(
        'a',
        'e',
        'i',
        'o',
        'u',
    );

    $consonant = array(
        'b',
        'c',
        'd',
        'f',
        'g',
        'h',
        'j',
        'k',
        'l',
        'm',
        'n',
        'p',
        'q',
        'r',
        's',
        't',
        'v',
        'w',
        'x',
        'y',
        'z',
    );

    $result = '';
    for ($i = 0; $i < $length; $i++) {
        if ($i % 2 == 0) {
            $result .= $consonant[rand(0, 15)];
        } else {
            $result .= $vowel[rand(0, 4)];
        }
    }

    return $result;
}

The result:

password(8);//kutekaku
password(11);//rahubabatul

I think better way to generate random password is below function, if someone want then you can use these for strong password

public function randPassword($upper = 2, $lower = 3, $numeric = 2, $other = 1) { 

        $pass_order = Array(); 
        $passWord = ''; 

        //Create contents of the password 
        for ($i = 0; $i < $upper; $i++) { 
            $pass_order[] = chr(rand(65, 90)); 
        } 
        for ($i = 0; $i < $lower; $i++) { 
            $pass_order[] = chr(rand(97, 122)); 
        } 
        for ($i = 0; $i < $numeric; $i++) { 
            $pass_order[] = chr(rand(48, 57)); 
        } 
        for ($i = 0; $i < $other; $i++) { 
            $pass_order[] = chr(rand(33, 47)); 
        } 

        //using shuffle() to shuffle the order
        shuffle($pass_order); 

        //Final password string 
        foreach ($pass_order as $char) { 
            $passWord .= $char; 
        } 
        return $passWord; 
    }