How to securely store and retrieve sensitive data in PHP?

@larissa 

There are several ways to securely store and retrieve sensitive data in PHP:

1. Use HTTPS: Always use HTTPS for transmitting sensitive data over the internet. HTTPS encrypts the data in transit, which prevents it from being intercepted by attackers.
2. Don’t store sensitive data in cookies: Cookies are not a secure place to store sensitive data. Instead, use server-side sessions to store sensitive data.
3. Use secure password hashing algorithms: Use secure password hashing algorithms such as bcrypt or Argon2 to store passwords. Never use MD5 or SHA1.
4. Parameterize SQL queries: Always use parameterized SQL queries to prevent SQL injection attacks.
5. Use prepared statements: Prepared statements are similar to parameterized queries and can help prevent SQL injection attacks.
6. Obfuscate configuration files: If you need to store sensitive data in a configuration file, store it in an obfuscated form. For example, use base64 encoding to store the data.
7. Use server-side encryption: Use server-side encryption to encrypt sensitive data at rest. This will prevent attackers from accessing the data if they gain access to the server.
8. Use a secure file system: Use a secure file system to store sensitive data. Make sure that the file system is properly secured and that access is restricted to authorized users only.
9. Use least privilege: Limit the access of users to sensitive data to the extent it is needed. This reduces the probability of data breach.
10. Perform frequent security audits: Regularly conduct security audits to check if the data is being stored and retrieved securely.