Several methods of generating random passwords in PHP

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Using PHP to develop applications, especially Web applications, often requires the generation of random passwords, such as user registration to generate random passwords, user reset password also need to generate a random password. Random password is a string of fixed length, here I collected several methods to generate random strings, for your reference.

Method One:

1, generate a random integer in the 33–126, such as 35,

2, convert 35 to the corresponding ASCII character, such as 35 corresponding #

3, repeat the above 1, 2 steps n times, connected to n-bit password

The algorithm mainly uses two functions, Mt_rand (int $min, int $max) function is used to generate random integers, where $min – $max the range of ASCII code, here take 33-126, you can adjust the range as necessary, such as the ASCII code table 97– 122 digits corresponding to the a–z of the English alphabet, specific reference to the ASCII code table; the Chr (int $ascii) function is used to convert the corresponding integer $ascii to the corresponding character.

function Create_password ($PW _length = 8) {$randpwd = ';     for ($i = 0; $i < $PW _length; $i + +) {$randpwd. = Chr (Mt_rand (33, 126)); } return $randpwd; }//Call this function, pass length parameter $pw_length = 6//echo Create_password (6);

Method Two:

1. Preset a string $chars, including a–z,a–z,0–9, and some special characters

2. Randomly take a character in a $chars string

3, repeat the second step n times, can get the length of the password of n

 function generate_password (  $length  = 8 )  {     / /  password character Set, you can add any characters you need       $chars  =  ' abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789 [email protected]#$%^&* ()-_  []{}<>~ ' +=,.;:/?| ';       $password  = ;     for  (  $i  =  0;  $i  <  $length;  $i ++ ) {          //  here are two ways to get a character          //  the first is to use &NBSP;SUBSTR   Intercept any one character in $chars;         //  the second is to take a character array   $chars Any element of            //  $password  .= substr ($chars,  mt_rand (0, strlen ($chars)  - 1),  1);           $password  .=  $charS[ mt_rand (0, strlen ($chars)  - 1)  ];     }      return  $password;  } echo generate_password (6);

Method Three:

The algorithm is simple, the code is short, just because the return value of the MD5 () function, the generated password only includes letters and numbers, but also a good way. Algorithm idea:

1. Time () Gets the current Unix timestamp

2, the first step to obtain the timestamp for MD5 () encryption

3, the second step to encrypt the result, intercept n-bit is the desired password

function Get_password ($length = 8) {$STR = substr (MD5 (Time ()), 0, 6); return $str; } Echo Get_password (6);

Time Efficiency comparison

We use the following PHP code, calculate the above 3 random password generation function generated 6-bit password run time, and then a simple comparison of their time efficiency.

function Getmicrotime () {list ($usec, $sec) = Explode ("", Microtime ()); return (float) $usec + (float) $sec);      }//Record start time $time _start = Getmicrotime ();   This puts the PHP code to execute, such as://Echo Create_password (6); Record end time $time _end = Getmicrotime ();   $time = $time _end-$time _start; Total run time of output echo "Execution time $time seconds";

The final result is:

Method One: 9.8943710327148E-5 seconds

Method Two: 9.6797943115234E-5 seconds

Method Three: 3.4093856811523E-5 seconds

It can be seen that the execution time of method one and method two is similar, and the shortest running time of method four.

Several methods of generating random passwords in PHP