Cryptography
Decryption
Definition
The reverse cryptographic operation that converts ciphertext back into its original plaintext using the appropriate algorithm and key.
Examples
- A web browser decrypts TLS records to display the page content.
- A user enters their FileVault passphrase, which decrypts the disk encryption key.
Related terms
Encryption
The cryptographic transformation of plaintext into ciphertext using an algorithm and key so that only authorized parties can recover the original data.
Symmetric Encryption
An encryption scheme in which the same secret key is used for both encryption and decryption, offering high speed and strong confidentiality when the key is shared securely.
Asymmetric Encryption
A cryptographic scheme that uses mathematically linked key pairs — a public key for encryption and a private key for decryption — to enable secure communication without prior secret sharing.
AES (Advanced Encryption Standard)
A NIST-standardized 128-bit block cipher with 128-, 192- or 256-bit keys, designed by Daemen and Rijmen and used as the dominant symmetric cipher worldwide.
Private Key
The secret half of an asymmetric key pair, used to decrypt ciphertext addressed to its owner or to create digital signatures that prove the owner's identity.
Cipher Suite
A named combination of cryptographic algorithms — key exchange, authentication, bulk encryption, and integrity — negotiated by protocols such as TLS for a given session.