In PHP applications, how can we securely handle user names and passwords instead of storing them as plain text?

Introduction / Context:
Handling user credentials securely is one of the most important responsibilities of any web application. Storing passwords in plain text or using weak encoding exposes users to serious risk if the database is compromised. PHP provides modern password hashing functions that greatly improve security when used correctly. This question asks how to handle user names and passwords securely rather than simply encrypting or storing them in an unsafe way.

Given Data / Assumptions:

• The application maintains a user table with login credentials.
• Attackers may gain access to database contents through vulnerabilities or misconfigurations.
• Modern PHP versions include password_hash and password_verify functions.
• Encryption and hashing are different operations, and passwords require specific handling.

Concept / Approach:
The best practice is to never store passwords in plain text. Instead, passwords should be hashed with a strong one way algorithm using password_hash, which automatically handles salts and cost factors. When a user logs in, the application uses password_verify to compare the entered password with the stored hash. User names can usually be stored as normal text, but if additional confidentiality is required for other fields, proper encryption libraries or extensions should be used rather than simple encodings. The key idea is that even if an attacker reads the database, they should not be able to recover passwords easily.

Step-by-Step Solution:
Step 1: During registration, read the plain password from the form and immediately hash it using password_hash with a strong algorithm such as PASSWORD_DEFAULT.Step 2: Store only the resulting hash in the database alongside the user name or email, never the original password.Step 3: At login time, retrieve the stored hash and call password_verify with the user supplied password and the hash.Step 4: If password_verify returns true, treat the login as successful and initialise a session; otherwise, reject the login attempt.Step 5: For any additional confidential fields, if encryption is needed, use established cryptographic libraries and manage keys carefully rather than inventing custom schemes.

Verification / Alternative check:
You can test this setup by examining the database contents after creating users. The password column should contain long hash strings that bear no obvious relationship to the original passwords. Attempting to log in with the correct password should succeed, while using any other password should fail because the hash comparison does not match. Security guidelines and frameworks for PHP consistently recommend password_hash and password_verify, confirming that this approach follows best practices.

Why Other Options Are Wrong:
Option B uses base64 encoding, which is reversible and not a security mechanism; anyone who accesses the stored values can decode them easily. Option C suggests emailing passwords after every login, which both exposes passwords in transit and encourages poor user habits. Option D proposes storing passwords directly in cookies without protection, which risks theft by cross site scripting or other attacks. These options do not provide adequate security for credential handling in modern applications.

Common Pitfalls:
A common pitfall is trying to design your own hashing or encryption scheme instead of relying on proven functions. Another mistake is using outdated algorithms such as md5 or sha1 without salting, which are vulnerable to dictionary and rainbow table attacks. Developers should also enforce strong password policies and consider multi factor authentication for sensitive systems. When migrating legacy applications, existing plain text or weakly hashed passwords should be upgraded gradually by rehashing them on successful login. Following these practices significantly improves protection for user credentials.

Final Answer:
Correct answer: By hashing passwords with functions such as password_hash and using proper cryptographic libraries for any encryption needs