encrypt

Encrypt is the verb for converting plaintext into ciphertext using an algorithm and a key, with the aim of preventing unauthorized access. Encryption is used to protect confidentiality both in storage and during transmission.

The essential elements are plaintext, ciphertext, an algorithm, and a key. The algorithm defines how the transformation occurs; the key controls the specific transformation. The security of encryption depends on the secrecy or strength of the key and the algorithm's resistance to cryptanalysis.

There are two main classes: symmetric encryption, where the same key encrypts and decrypts; and asymmetric encryption, which uses a public key for encryption and a private key for decryption. Symmetric algorithms include AES and ChaCha20; asymmetric include RSA, DSA, and ECC-based schemes. Many systems combine them in a hybrid approach, using asymmetric methods to exchange a symmetric session key.

Applications include securing data in transit (for example, TLS/HTTPS) and data at rest (disk encryption, file encryption). Email encryption, secure messaging, and digital rights management rely on encryption. Standards bodies such as NIST provide guidelines for selecting algorithms and key lengths.

Limitations include key management challenges, potential weaknesses in implementations, and the need for end-to-end trust to avoid metadata leakage. Ethics and regulation influence encryption use in different jurisdictions.