Summary of methods for generating random passwords in PHP, summary of PHP generation_PHP tutorial

Summary of methods for generating random passwords in PHP, summary of PHP generation

Using PHP to develop applications, especially website programs, often requires generating random passwords, such as user registration to generate random passwords, users Resetting your password also requires generating a random 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 character, such as 35 corresponding to #

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

This algorithm mainly uses two functions. The mt_rand (int $min, int $max) function is used to generate random integers, where $min – $max is the range of ASCII codes. Here, it is 33-126, which can be used as needed. Adjustment range, for example, 97 – 122 bits in the ASCII code table correspond to the English letters a – z. For details, please refer to the ASCII code table; chr (int $ascii) function is used to convert the corresponding integer $ascii into 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 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 from 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
 $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_ []{}<>~`+=,.;:/&#63;|';

 $password = '';
 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 obtained key name array $keys, take out 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
 $chars = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 
 'i', 'j', 'k', 'l','m', 'n', 'o', 'p', 'q', 'r', 's', 
 't', 'u', 'v', 'w', 'x', 'y','z', 'A', 'B', 'C', 'D', 
 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L','M', 'N', 'O', 
 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y','Z', 
 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '!', 
 '@','#', '$', '%', '^', '&', '*', '(', ')', '-', '_', 
 '[', ']', '{', '}', '<', '>', '~', '`', '+', '=', ',', 
 '.', ';', ':', '/', '&#63;', '|');
 // 在 $chars 中随机取 $length 个数组元素键名
 $keys = array_rand($chars, $length); 
 $password = '';
 for($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 of the return value of the md5() function, the generated password only includes letters and numbers. But it’s still a good method. Algorithmic thinking:

1. time() gets the current Unix timestamp

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

3. Intercept n digits from the encryption result of the second step to get 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 running time of the above four random password generation functions to generate a 6-digit password, and then conduct a simple comparison of their time efficiency.

<&#63;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";
&#63;>

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 2: 9.6797943115234E-5 seconds

Method 3: 0.00017499923706055 seconds

Method 4: 3.4093856811523E-5 seconds

It can be seen that the execution time of method one and method two is similar. Method four has the shortest running time, while method three has a slightly longer running time.

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