Cipher
What is Cipher?
CipherAlgorithm that transforms plaintext into ciphertext (encryption) and back (decryption), parameterized by one or more cryptographic keys.
A cipher is the algorithm that performs encryption and decryption. Modern ciphers fall into symmetric (single shared key, e.g., AES, ChaCha20, 3DES) and asymmetric (public/private key pair, e.g., RSA, ECC) families, and into block ciphers (fixed-size blocks, e.g., AES-128) or stream ciphers (one bit/byte at a time, e.g., ChaCha20). A cipher is typically composed with a mode of operation (CBC, GCM, CTR) and key-derivation, MAC, or AEAD construction to achieve confidentiality and integrity together. Choosing a strong cipher today means AEAD constructions like AES-GCM, AES-GCM-SIV, or ChaCha20-Poly1305 with proper IV/nonce handling.
● Examples
- 01
TLS 1.3 cipher suite TLS_AES_128_GCM_SHA256.
- 02
Disk encryption using AES-XTS-256.
● Frequently asked questions
What is Cipher?
Algorithm that transforms plaintext into ciphertext (encryption) and back (decryption), parameterized by one or more cryptographic keys. It belongs to the Cryptography category of cybersecurity.
What does Cipher mean?
Algorithm that transforms plaintext into ciphertext (encryption) and back (decryption), parameterized by one or more cryptographic keys.
How does Cipher work?
A cipher is the algorithm that performs encryption and decryption. Modern ciphers fall into symmetric (single shared key, e.g., AES, ChaCha20, 3DES) and asymmetric (public/private key pair, e.g., RSA, ECC) families, and into block ciphers (fixed-size blocks, e.g., AES-128) or stream ciphers (one bit/byte at a time, e.g., ChaCha20). A cipher is typically composed with a mode of operation (CBC, GCM, CTR) and key-derivation, MAC, or AEAD construction to achieve confidentiality and integrity together. Choosing a strong cipher today means AEAD constructions like AES-GCM, AES-GCM-SIV, or ChaCha20-Poly1305 with proper IV/nonce handling.
How do you defend against Cipher?
Defences for Cipher typically combine technical controls and operational practices, as detailed in the full definition above.
● Related terms
- cryptography№ 105
Block Cipher
A symmetric cipher that encrypts fixed-size blocks of plaintext with a secret key, usually combined with a mode of operation to handle data of arbitrary length.
- cryptography№ 1109
Stream Cipher
A symmetric cipher that encrypts data one bit or byte at a time by XORing it with a pseudorandom keystream derived from a key and nonce.
- cryptography№ 172
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.
- cryptography№ 1121
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.
- cryptography№ 067
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.
- cryptography№ 379
Encryption
The cryptographic transformation of plaintext into ciphertext using an algorithm and key so that only authorized parties can recover the original data.
● See also
- № 832Plaintext
- № 173Ciphertext