Should You Cleanse Passwords Before Hashing in PHP?

PHP Password Hashing: Avoid unnecessary cleanup steps

Protecting user passwords is critical, but the way they are prepared for storage is often misunderstood. Many PHP developers unnecessarily sanitize or escape passwords before hashing them, which reduces security.

Misunderstandings about password cleaning

Sanitizing passwords before hashing introduces unnecessary complexity and security risks:

• Redundant Code: Additional cleanup steps increase the amount of code, thereby increasing the likelihood of errors and vulnerabilities.
• SQL injection risk does not exist: Hashed passwords do not pose a SQL injection threat because the strings are converted to hashes before being stored in the database.
• Inconsistent verification requirements: The cleaning method will affect the content of the password, resulting in inconsistent password verification requirements.

The power of hashing

Hash the password so that it is stored securely in the database because of the hash function:

• Treat all bytes equally, no sanitization required for security reasons.
• Generate a fixed-length string (e.g. 60 characters for BCRYPT) regardless of password complexity.

Handling various inputs

Hashes securely store even complex passwords containing spaces, special characters, and even full SQL queries. This robust approach eliminates the need for length restrictions or character validation.

Impact of cleaning methods

Applying different sanitization methods to passwords can produce different results, complicating future password verification. For example, trim() might remove trailing spaces, while htmlspecialchars() might change quotes and ampersands.

The correct approach

When using PHP’s password_hash() function to securely store passwords, be sure to avoid any sanitization mechanisms. Just pass the password provided by the original user to the function. This approach ensures:

• Security: Hashed passwords are immune to SQL injection attacks and comply with industry best practices.
• Efficiency: No additional code or processing required, minimizing potential vulnerabilities.
• Consistency: Password verification works as expected without prior cleanup steps.

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