Symmetric Encryption

is a method of encrypting and decrypting data using the same secret key.

• AKA: secret-key, single-key, or private-key encryption.
• The secret key is shared between both parties. (increases the risk)
• The same key is used to encrypt and decrypt the message.
• It can use block or stream ciphers.
• Pros: good for volumes of data, files, databases, and networks. Fast.
• Pros: confidentiality, integrity, and authentication
• Cons: How do I share the key? How do I scale for multiple users? (multiple keys)
• Cons: Doesn’t support non-repudiation.
• Examples: Blowfish, RC4, DES, Triple DES (3DES), and AES (most popular).
• Examples: ChaCha20 (used by TLS 1.3, for instance)