Should I Cleanse User Passwords Before Hashing in PHP?

Cleansing User Passwords: A Comprehensive Guide

When safeguarding user passwords, PHP developers often resort to cleansing mechanisms like escape_string() and htmlspecialchars(). However, this practice is not advisable for passwords, as it unnecessarily complicates the process and provides no additional security benefits.

Password Hashing for Security

The primary purpose of hashing passwords is to render them secure for storage in databases. Hashed passwords are not plaintext and cannot be directly used for SQL injection attacks, making cleansing irrelevant for security purposes.

Unnecessary Additional Code

Cleansing passwords introduces unnecessary code that serves no real function. The password_hash() function already handles all necessary transformations to make passwords safe for storage.

Allow User Flexibility

By avoiding cleansing mechanisms, you allow users to choose longer and more complex passwords. This enhances security, as it increases the difficulty for attackers to crack the passwords.

Password Storage Considerations

The most commonly used hashing method, PASSWORD_BCRYPT, creates a 60-character hash that includes the password, a random salt, and an algorithmic cost. It is recommended to store hashed passwords in a VARCHAR(255) or TEXT column to accommodate future expansions in hashing methods.

Example of Password Cleansing Impact

Consider the following password: "I'm a "dessert topping" & a !". Applying different cleansing methods yields inconsistent results, none of which are necessary for hashing.

Cleansing Method	Result
Trim	"I'm a "dessert topping" & a !"
Htmlentities	"I'm a "dessert topping" & a !"
Addslashes	"I'm a "dessert topping" & a !"
Strip_tags	"I'm a "dessert topping" & a !"

Regardless of the cleansing method employed, all passwords will be hashed successfully. However, issues arise when verifying passwords, as the cleansing method must be applied again before comparison with password_verify().

Conclusion

Cleansing user passwords before hashing is an unnecessary and potentially harmful practice. Instead, focus on using a secure hashing algorithm like PASSWORD_BCRYPT and allow users to choose strong passwords. By avoiding cleansing mechanisms, you simplify the process and enhance the security of your stored passwords.

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