To determine the strength of the password, it is necessary to combine regular and logical processing. The basic requirements include: 1. The length is no less than 8 digits; 2. At least containing lowercase letters, uppercase letters, and numbers; 3. Special character restrictions can be added; in terms of advanced aspects, continuous duplication of characters and incremental/decreasing sequences need to be avoided, which requires PHP function detection; at the same time, blacklists should be introduced to filter common weak passwords such as password and 123456; finally it is recommended to combine the zxcvbn library to improve the evaluation accuracy.
Judging password strength is a common requirement in development, and regular expressions are usually implemented in PHP. But writing a regex is not enough, you have to understand the logic and application scenarios behind it.
Basic requirements: length and character type
The simplest password strength rules usually include the minimum length (such as 8 digits) and contain at least several types of characters (lower and lower case letters, numbers, special symbols).
$pattern = '/^(?=.*[az])(?=.*[AZ])(?=.*\d).{8,}$/';This rule means:
-
(?=.*[az])has at least one lowercase letter -
(?=.*[AZ])has at least one capital letter -
(?=.*\d)Have at least one number -
.{8,}The total length is no less than 8 digits
If you want to add another special character, you can add:
(?=.*[!@#$%^&*])
Advanced Limits: Avoid continuous or repeated characters
Some systems will prohibit users from setting obvious and regular passwords like 123456 or aaaabbbb . At this time, the rules are not enough, and it is necessary to combine PHP's logical judgment.
For example, detect whether there are more than three consecutive identical characters:
function hasConsecutiveChars($password) {
return preg_match('/(\w)\1{2,}/', $password);
} Or check whether there are simple increment/decreasing sequences (such as abc , 321 ), which requires traversing the strings one by one, and cannot rely solely on regularity.
Avoid common weak passwords
Even if the character type and length requirements are met, users may enter common weak passwords such as Password123 and Qwerty123 . It is recommended to introduce a blacklist mechanism at this time:
$weakPasswords = ['password', '123456', 'qwerty'];
if (in_array(strtolower($password), $weakPasswords)) {
// The password is too weak, refuse to use}A more advanced approach is to integrate libraries like zxcvbn to do real strength evaluation, but that is another topic.
Basically that's it. Using regular control infrastructure, co-processing complex situations with PHP logic, and blacklist filtering can basically meet the needs of most projects. It is not complicated but it is easy to ignore details, such as boundary conditions or coding issues. Remember to cover several input forms during testing.
The above is the detailed content of php regex for password strength. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How do I implement authentication and authorization in PHP?
Jun 20, 2025 am 01:03 AM
TosecurelyhandleauthenticationandauthorizationinPHP,followthesesteps:1.Alwayshashpasswordswithpassword_hash()andverifyusingpassword_verify(),usepreparedstatementstopreventSQLinjection,andstoreuserdatain$_SESSIONafterlogin.2.Implementrole-basedaccessc
How can you handle file uploads securely in PHP?
Jun 19, 2025 am 01:05 AM
To safely handle file uploads in PHP, the core is to verify file types, rename files, and restrict permissions. 1. Use finfo_file() to check the real MIME type, and only specific types such as image/jpeg are allowed; 2. Use uniqid() to generate random file names and store them in non-Web root directory; 3. Limit file size through php.ini and HTML forms, and set directory permissions to 0755; 4. Use ClamAV to scan malware to enhance security. These steps effectively prevent security vulnerabilities and ensure that the file upload process is safe and reliable.
What are the differences between == (loose comparison) and === (strict comparison) in PHP?
Jun 19, 2025 am 01:07 AM
In PHP, the main difference between == and == is the strictness of type checking. ==Type conversion will be performed before comparison, for example, 5=="5" returns true, and ===Request that the value and type are the same before true will be returned, for example, 5==="5" returns false. In usage scenarios, === is more secure and should be used first, and == is only used when type conversion is required.
How do I perform arithmetic operations in PHP ( , -, *, /, %)?
Jun 19, 2025 pm 05:13 PM
The methods of using basic mathematical operations in PHP are as follows: 1. Addition signs support integers and floating-point numbers, and can also be used for variables. String numbers will be automatically converted but not recommended to dependencies; 2. Subtraction signs use - signs, variables are the same, and type conversion is also applicable; 3. Multiplication signs use * signs, which are suitable for numbers and similar strings; 4. Division uses / signs, which need to avoid dividing by zero, and note that the result may be floating-point numbers; 5. Taking the modulus signs can be used to judge odd and even numbers, and when processing negative numbers, the remainder signs are consistent with the dividend. The key to using these operators correctly is to ensure that the data types are clear and the boundary situation is handled well.
How can you interact with NoSQL databases (e.g., MongoDB, Redis) from PHP?
Jun 19, 2025 am 01:07 AM
Yes, PHP can interact with NoSQL databases like MongoDB and Redis through specific extensions or libraries. First, use the MongoDBPHP driver (installed through PECL or Composer) to create client instances and operate databases and collections, supporting insertion, query, aggregation and other operations; second, use the Predis library or phpredis extension to connect to Redis, perform key-value settings and acquisitions, and recommend phpredis for high-performance scenarios, while Predis is convenient for rapid deployment; both are suitable for production environments and are well-documented.
How do I stay up-to-date with the latest PHP developments and best practices?
Jun 23, 2025 am 12:56 AM
TostaycurrentwithPHPdevelopmentsandbestpractices,followkeynewssourceslikePHP.netandPHPWeekly,engagewithcommunitiesonforumsandconferences,keeptoolingupdatedandgraduallyadoptnewfeatures,andreadorcontributetoopensourceprojects.First,followreliablesource
What is PHP, and why is it used for web development?
Jun 23, 2025 am 12:55 AM
PHPbecamepopularforwebdevelopmentduetoitseaseoflearning,seamlessintegrationwithHTML,widespreadhostingsupport,andalargeecosystemincludingframeworkslikeLaravelandCMSplatformslikeWordPress.Itexcelsinhandlingformsubmissions,managingusersessions,interacti
How to set PHP time zone?
Jun 25, 2025 am 01:00 AM
TosettherighttimezoneinPHP,usedate_default_timezone_set()functionatthestartofyourscriptwithavalididentifiersuchas'America/New_York'.1.Usedate_default_timezone_set()beforeanydate/timefunctions.2.Alternatively,configurethephp.inifilebysettingdate.timez
