4 ways to generate random passwords with PHP and performance comparison

Using PHP to develop applications, especially website programs, often requires generating random passwords. For example, a random password is generated for user registration, and a random password is also required for user reset 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 character, such as 35 corresponding to #

3. Repeat the above 1 , 2 steps n times, concatenate into 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 ASCII code. Range, here is 33-126, you can adjust the range as needed. 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 Convert $ascii to the corresponding characters.

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<ol>
<li><span><span>function</span><span> create_password(</span><span>$pw_length</span><span> = 8) </span></span></li>
<li><span>{ </span></li>
<li><span>    <span>$randpwd</span><span> = </span><span>''</span><span>; </span></span></li>
<li><span>    <span>for</span><span> (</span><span>$i</span><span> = 0; </span><span>$i</span><span> <span>$pw_length</span><span>; </span><span>$i</span><span>++)  </span></span></span></li>
<li><span>    { </span></li>
<li><span>        <span>$randpwd</span><span> .= </span><span>chr</span><span>(mt_rand(33, 126)); </span></span></li>
<li><span>    } </span></li>
<li><span>    <span>return</span><span> </span><span>$randpwd</span><span>; </span></span></li>
<li><span>} </span></li>
<li><span> </span></li>
<li><span><span>// 调用该函数，传递长度参数$pw_length = 6</span><span> </span></span></li>
<li><span><span>echo</span><span> create_password(6); </span></span></li>
</ol>

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

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<ol>
<li><span><span>function</span><span> generate_password( </span><span>$length</span><span> = 8 ) { </span></span></li>
<li><span>    <span>// 密码字符集，可任意添加你需要的字符</span><span> </span></span></li>
<li><span>    <span>$chars</span><span> = </span><span>'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_ []{}~`+=,.;:/?|'</span><span>; </span></span></li>
<li><span> </span></li>
<li><span>    <span>$password</span><span> = </span><span>''</span><span>; </span></span></li>
<li><span>    <span>for</span><span> ( </span><span>$i</span><span> = 0; </span><span>$i</span><span> <span>$length</span><span>; </span><span>$i</span><span>++ )  </span></span></span></li>
<li><span>    { </span></li>
<li><span>        <span>// 这里提供两种字符获取方式</span><span> </span></span></li>
<li><span>        <span>// 第一种是使用 substr 截取$chars中的任意一位字符；</span><span> </span></span></li>
<li><span>        <span>// 第二种是取字符数组 $chars 的任意元素</span><span> </span></span></li>
<li><span>        <span>// $password .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);</span><span> </span></span></li>
<li><span>        <span>$password</span><span> .= </span><span>$chars</span><span>[ mt_rand(0, </span><span>strlen</span><span>(</span><span>$chars</span><span>) - 1) ]; </span></span></li>
<li><span>    } </span></li>
<li><span> </span></li>
<li><span>    <span>return</span><span> </span><span>$password</span><span>; </span></span></li>
<li><span>} </span></li>
</ol>

Method 3:

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

2. Use array_rand() to randomly select $length elements from the array $chars

3. According to the acquired key name array $keys, extract 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.

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

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 md5() Because of the return value of the function, the generated password only includes letters and numbers, but it is still a good method. Algorithm idea:

1. time() obtains the current Unix timestamp

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

3. Intercept n bits of the encrypted result in the second step. Wanted password

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<ol>
<li><span><span>function</span><span> get_password( </span><span>$length</span><span> = 8 )  </span></span></li>
<li><span>{ </span></li>
<li><span>    <span>$str</span><span> = </span><span>substr</span><span>(md5(time()), 0, 6); </span></span></li>
<li><span>    <span>return</span><span> </span><span>$str</span><span>; </span></span></li>
<li><span>} </span></li>
</ol>

Time efficiency comparison

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

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

The final result is:

Method one: 9.8943710327148E-5 seconds

Method two: 9.6797943115234E-5 seconds

Method Three: 0.00017499923706055 seconds

Method 4: 3.4093856811523E-5 seconds

It can be seen that the execution time of method 1 and method 2 are similar. Method 4 has the shortest running time, while method 3 has a slightly longer running time.

The above introduces the four methods of generating random passwords in PHP and their performance comparison, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.