Symmetric Encryption
What is Symmetric Encryption?
Symmetric EncryptionAn 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.
Symmetric encryption — also called secret-key or shared-key cryptography — uses a single key, known to all communicating parties, for both encrypting plaintext and decrypting ciphertext. It comes in two main flavours: block ciphers (AES, 3DES, Blowfish) that operate on fixed-size blocks, and stream ciphers (ChaCha20, Salsa20) that produce a keystream XORed with the plaintext. AES-128 and AES-256 in authenticated modes such as GCM or OCB are the modern standards, offering both speed (often hardware-accelerated via AES-NI) and security. The main weakness is key distribution: every pair of parties must share a secret, which is typically solved by combining symmetric encryption with asymmetric key exchange (e.g., Diffie–Hellman) inside protocols like TLS.
● Examples
- 01
TLS 1.3 uses AES-GCM or ChaCha20-Poly1305 for symmetric encryption of records.
- 02
Full-disk encryption (BitLocker, LUKS) relies on symmetric ciphers.
● Frequently asked questions
What is 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. It belongs to the Cryptography category of cybersecurity.
What does Symmetric Encryption mean?
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.
How do you defend against Symmetric Encryption?
Defences for Symmetric Encryption typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for Symmetric Encryption?
Common alternative names include: Secret-key encryption, Shared-key encryption.