Five ways to generate random passwords in php

This article mainly introduces five methods of generating random passwords in PHP. Interested friends can refer to it. I hope it will be helpful to everyone.

Using PHP to develop applications, especially website programs, often requires generating random passwords. For example, when a user registers to generate a random password, the user also needs to generate a random password to reset the password. A random password is a string of fixed length. Here I have collected several methods of generating random strings for your reference.

Method 1:

1. Generate a random integer from 33 – 126, such as 35,

2. Convert 35 into the corresponding ASCII code characters, such as 35 corresponds to

# 3. Repeat the above steps 1 and 2 n times to connect into an n-digit password

This algorithm mainly uses two functions, mt_rand ( int $ min, int $max) function is used to generate random integers, where $min – $max is the range of ASCII code, here it is 33-126, the range can be adjusted as needed, for example, 97 – 122 bits in the ASCII code table correspond to a – z English letters, please refer to the ASCII code table for details; chr (int $ascii) function is used to convert the corresponding integer $ascii into the corresponding characters.

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 and pass the length parameter $pw_length = 6

echo create_password(6);

Method 2:

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

2. Randomly pick a character in the $chars string

3. Repeat the second step n times to get a password of length n

function generate_password( $length = 8 ) {
 // 密码字符集，可任意添加你需要的字符
 $chars = &#39;abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_ []{}<>~`+=,.;:/?|&#39;;

 $password = &#39;&#39;;
 for ( $i = 0; $i < $length; $i++ ) 
 {
  // 这里提供两种字符获取方式
  // 第一种是使用 substr 截取$chars中的任意一位字符；
  // 第二种是取字符数组 $chars 的任意元素
  // $password .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
  $password .= $chars[ mt_rand(0, strlen($chars) - 1) ];
 }

 return $password;
}

Method 3:

1. Preset a character array $chars, including a – z, A – Z, 0 – 9, and some special characters

2. Randomly select $length elements

from the array $chars through array_rand() 3. According to the Get the key name array $keys, take the characters from the array $chars and concatenate the string. The disadvantage of this method is that the same characters will not be retrieved repeatedly.

function make_password( $length = 8 )
{
 // 密码字符集，可任意添加你需要的字符
 $chars = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 
 'i', 'j', 'k', 'l','m', 'n', 'o', 'p', 'q', 'r', 's', 
 't', 'u', 'v', 'w', 'x', 'y','z', 'A', 'B', 'C', 'D', 
 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L','M', 'N', 'O', 
 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y','Z', 
 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '!', 
 '@','#', '$', '%', '^', '&', '*', '(', ')', '-', '_', 
 &#39;[&#39;, &#39;]&#39;, &#39;{&#39;, &#39;}&#39;, &#39;<&#39;, &#39;>&#39;, &#39;~&#39;, &#39;`&#39;, &#39;+&#39;, &#39;=&#39;, &#39;,&#39;, 
 &#39;.&#39;, &#39;;&#39;, &#39;:&#39;, &#39;/&#39;, &#39;?&#39;, &#39;|&#39;);
 // 在 $chars 中随机取 $length 个数组元素键名
 $keys = array_rand($chars, $length); 
 $password = &#39;&#39;;
 for($i = 0; $i < $length; $i++)
 {
  // 将 $length 个数组元素连接成字符串
  $password .= $chars[$keys[$i]];
 }
 return $password;
}

Method 4:

This method is a new method provided by a netizen after this article was reprinted by Blue Ideal. The algorithm is simple and the code is short, just because Because of the return value of the md5() function, the generated password only includes letters and numbers, but it is still a good method. Algorithm idea:

1. time() gets the current Unix timestamp

2. Encrypt the timestamp obtained in the first step with md5()

3. As a result of the second step of encryption, n bits are intercepted to obtain the desired password

function get_password( $length = 8 ) 
{
 $str = substr(md5(time()), 0, 6);
 return $str;
}

Time efficiency comparison

We use the following PHP code to calculate the above 4 random The running time of the password generation function to generate a 6-digit password, and then a simple comparison of their time efficiency was performed.

<?php
function getmicrotime()
{
 list($usec, $sec) = explode(" ",microtime());
 return ((float)$usec + (float)$sec);
}
// 记录开始时间
$time_start = getmicrotime();
// 这里放要执行的PHP代码，如:
// echo create_password(6);
// 记录结束时间
$time_end = getmicrotime();
$time = $time_end - $time_start;
 // 输出运行总时间 
echo "执行时间 $time seconds";
?>

Method 5:

function rand_string($len = 16, $keyword = '') {
 if (strlen($keyword) > $len) {//关键字不能比总长度长
  return false;
 }
 $str = '';
 $chars = 'abcdefghijkmnpqrstuvwxyz23456789ABCDEFGHIJKMNPQRSTUVWXYZ'; //去掉1跟字母l防混淆   
 if ($len > strlen($chars)) {//位数过长重复字符串一定次数
  $chars = str_repeat($chars, ceil($len / strlen($chars)));
 }
 $chars = str_shuffle($chars); //打乱字符串
 $str = substr($chars, 0, $len);
 if (!empty($keyword)) {
  $start = $len - strlen($keyword);
  $str = substr_replace($str, $keyword, mt_rand(0, $start), strlen($keyword)); //从随机位置插入关键字
 }
 return $str;
}

echo rand_string(16,"ab"); //output example:V8bNY6SmkeywordB
?>

The final result is:

Method 1: 9.8943710327148E-5 seconds

Method two: 9.6797943115234E-5 seconds

Method three: 0.00017499923706055 seconds

Method four: 3.4093856811523E-5 seconds

You can see that method one The execution time of method 2 is similar, method 4 has the shortest running time, and method 3 has a slightly longer running time.

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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