PHP regular expression method to verify password complexity

With the gradual improvement of network security awareness, many websites have begun to require users to use complex passwords. As a widely used programming language, PHP naturally needs corresponding methods to verify the complexity of passwords. This article will introduce the method of verifying password complexity using PHP regular expressions.

1. Password complexity requirements

Before designing the regular expression for password complexity verification, we need to first determine the password complexity requirements. Generally speaking, password complexity requirements include the following aspects:

1. Password length: The password length cannot be less than a certain value, generally 8-16 characters.
2. Character types: Password must contain uppercase and lowercase letters, numbers and special characters (such as !@#$%^&*()_ -=[]{}|;':",./
3. Common passwords cannot be used: the password cannot contain common passwords (such as: 123456, admin, etc.).

2. PHP regular expressions Methods to verify password complexity

1. Verify password length

It is very simple to use regular expressions to verify password length, just use ".{8,16}" . Among them, the dot indicates that any character can be matched, the 8 in the curly brackets indicates that at least 8 characters must be matched, and 16 indicates that a maximum of 16 characters must be matched.

Sample code:

if(preg_match('/.{8,16}/',$password)){
  echo '密码长度符合要求';
}else{
  echo '密码长度不符合要求';
}

2. Verification password character types

Verification password character types are more complicated, and you need to use "[]" in regular expressions to represent the matching character set. The specific implementation method is as follows:

//验证是否包含数字
if(preg_match('/[0-9]+/',$password)){
  $score++;
}

//验证是否包含小写字母
if(preg_match('/[a-z]+/',$password)){
  $score++;
}

//验证是否包含大写字母
if(preg_match('/[A-Z]+/',$password)){
  $score++;
}

//验证是否包含特殊字符
if(preg_match('/[!@#$%^&*()_+-=[]{}|;:'",./<>?]+/',$password)){
  $score++;
}

if($score>=3){
  echo '密码复杂度符合要求';
}else{
  echo '密码复杂度不符合要求';
}

In the above code, we use several regular expressions to verify whether the password meets the requirements. Among them, the square brackets "[]" indicate a matching character set, and the plus sign " " indicates that the character set must appear at least once.

3. Verify whether common passwords are included

Verifying whether common passwords are included is also relatively simple. You only need to use the "|" in the regular expression to express the "or" relationship. . The specific implementation method is as follows:

//常用密码列表
$commonPasswords = array('123456','admin','password','qwerty','12345678');

//验证密码是否为常用密码
if(preg_match('/('.implode('|', $commonPasswords).')/i', $password)){
  echo '密码为常用密码';
}else{
  echo '密码不为常用密码';
}

In the above code, we use the implode function to connect the elements in the commonly used password list with vertical lines to form a regular expression. Among them, the parentheses "( )" means that the match is a string, and "i" means that the case is ignored when matching.

3. Summary

The method of verifying password complexity with PHP regular expressions mainly includes verifying passwords Length, password character type and whether it contains commonly used passwords. Programmers can design their own password complexity verification regular expressions according to specific needs, which improves password security while making it more convenient for users.

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