There are many techniques to protect your data; some of them are as follows:
Encryption and decryption: This is a two-way process to convert your data from clear-text into crypto-text and back again.
Hashes: This is a one-way process to generate a hash value to securely store passwords or that can be used to detect malicious changes or corruption of your data.
Signatures: This technique is used to ensure that data has come from someone you trust by validating a signature that has been applied to some data against someone's public key.
Authentication: This technique is used to identify someone by checking their credentials.
Authorization: This technique is used to ensure that someone has permission to perform an action or work with some data by checking the roles or groups they belong to.
Note
Authentication and authorization will be covered in Chapter 14, Building Web Applications Using ASP.NET Core MVC.