Simple definition
Encryption converts readable data into ciphertext using a cryptographic algorithm and a key. An authorized recipient uses the appropriate key to recover the original data.
Technical definition
Symmetric encryption uses a shared secret key. Asymmetric cryptography uses a related public and private key pair. Protocols such as TLS combine cryptographic mechanisms to protect communication; disk encryption protects stored data.
What is it used for?
Protect confidential information in storage and in transit. The choice of algorithm, key management and access controls all affect the protection provided.
Practical example
An HTTPS connection protects application traffic between the browser and the server. Disk encryption protects data on a locked device; an authorized, unlocked session can still access its files.
Common issues
- Losing the recovery key or granting excessive access to keys.
- Using obsolete cryptographic algorithms or invalid certificates.
- Assuming that encryption alone provides a backup or prevents an authorized session from deleting data.
- Using reversible encryption to store login passwords when a dedicated password-hashing function is required.