Describe encryption and hashing


One way to mitigate against common cybersecurity threats is to encrypt sensitive or valuable data. Encryption is the process of making data unreadable and unusable to unauthorized viewers. To use or read encrypted data, it must be decrypted, which requires the use of a secret key.

There are two top-level types of encryption: symmetric and asymmetric. Symmetric encryption uses the same key to encrypt and decrypt the data. Asymmetric encryption uses a public key and private key pair. Either key can encrypt data, but a single key can’t be used to decrypt encrypted data. To decrypt, you need a paired key. Asymmetric encryption is used for things such accessing sites on the internet using the HTTPS protocol and electronic data signing solutions. Encryption may protect data at rest, or in transit.

The concept of symmetric and asymmetric encryption

Encryption for data at rest

Data at rest is the data that's stored on a physical device, such as a server. It may be stored in a database or a storage account but, regardless of where it's stored, encryption of data at rest ensures the data is unreadable without the keys and secrets needed to decrypt it.

If an attacker obtained a hard drive with encrypted data and didn't have access to the encryption keys, they would be unable to read the data.

Encryption for data in transit

Data in transit is the data moving from one location to another, such as across the internet or through a private network. Secure transfer can be handled by several different layers. It could be done by encrypting the data at the application layer before sending it over a network. HTTPS is an example of encryption in transit.

Encrypting data in transit protects it from outside observers and provides a mechanism to transmit data while limiting the risk of exposure.

Encryption for data in use

A common use case for encryption of data in use involves securing data in nonpersistent storage, such as RAM or CPU caches. This can be achieved through technologies that create an enclave (think of this as a secured lockbox) that protects the data and keeps data encrypted while the CPU processes the data.


Hashing uses an algorithm to convert text to a unique fixed-length value called a hash. Each time the same text is hashed using the same algorithm, the same hash value is produced. That hash can then be used as a unique identifier of its associated data.

Hashing is different to encryption in that it doesn't use keys, and the hashed value isn't subsequently decrypted back to the original.

Hashing is often used to store passwords. When a user enters their password, the same algorithm that created the stored hash creates a hash of the entered password. This is compared to the stored hashed version of the password. If they match, the user has entered their password correctly. This is more secure than storing plain text passwords, but hashing algorithms are also known to hackers. Because hash functions are deterministic (the same input produces the same output), hackers can use brute-force dictionary attacks by hashing the passwords. For every matched hash, they know the actual password. To mitigate this risk, passwords are often “salted”. This refers to adding a fixed-length random value to the input of hash functions to create unique hashes for same input.

The concept of hashing