Скачать или смотреть Understanding password_verify() and Secure Authentication in PHP

Learn how to effectively use `password_verify()` in PHP for secure user authentication and understand common pitfalls in password handling.
---
This video is based on the question https://stackoverflow.com/q/63051381/ asked by the user 'yeahgd' ( https://stackoverflow.com/u/12690646/ ) and on the answer https://stackoverflow.com/a/63053469/ provided by the user 'yeahgd' ( https://stackoverflow.com/u/12690646/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Password_verify() gives true if the pwd is contained in the string to parse

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding password_verify() and Secure Authentication in PHP

When developing web applications, one of the key aspects is ensuring secure user authentication. This often involves verifying user passwords safely and effectively. However, if not handled correctly, developers might encounter issues similar to a problem raised in the PHP community regarding the password_verify() function. In this guide, we'll dive into this common problem and explore the appropriate solutions to secure password handling.

The Issue: Password Verification Misfires

Recently, a developer faced a perplexing situation where password_verify() returned true for incorrect passwords. Here's a simplified version of the problem they encountered:

The developer was using password_verify() to check a password provided in a URL against a hashed password retrieved from a database.

Unexpectedly, passwords that included incorrect characters were still being verified as correct.

The code snippet below illustrates the scenario:

[[See Video to Reveal this Text or Code Snippet]]

The developer’s concern was that password_verify() was allowing incorrect variants of a password to pass as valid, leading to potential security vulnerabilities.

The Solution: Use of password_hash()

Understanding the Problem

After delving deeper into the situation, the developer realized a critical mistake: the application wasn't consistently using the right hashing functions throughout the password handling process. Instead of password_hash(), an outdated function called crypt() was used earlier during password creation. Here’s why this is important:

Inconsistent Hashing: Using different functions leads to incompatible hashes, resulting in unpredictable behavior. If crypt() generated hashes improperly or used an unsuitable salt, it would explain the verification issues.

Transition to Secure Hashing

The developer decided to switch to password_hash() consistently throughout the application. Here’s why this was a solid choice:

Built-in Security: password_hash() not only provides a strong hashing algorithm but also manages the creation of salts automatically. This reduces the risk of reusing salts or incorrectly implementing cryptographic principles.

Compatibility with password_verify(): By using password_hash() for hashing, the verification process becomes straightforward and reliable, ensuring that password_verify() works as expected.

Implementation Steps

Update Account Creation: Ensure that when creating user accounts, the password is hashed using password_hash():

[[See Video to Reveal this Text or Code Snippet]]

Consistent Verification: Use the same password_verify() pattern for checking user logins as shown in the code snippet above.

Testing: After updating the authentication logic, rigorously test various input scenarios to confirm that only exact password matches validate successfully.

Conclusion

The transition from an outdated cryptographic approach to modern PHP’s password_hash() not only resolved the developer's issue but also enhanced the security of the entire authentication system. For anyone involved in PHP development, prioritizing password hashing and verification using built-in functions is crucial for safeguarding user data and maintaining trust.

By understanding and addressing such common pitfalls, developers can create safer web applications that better protect user credentials. Always remember, using the right tools for authentication is essential for building secure online services.