Understanding SSH terminology

  • RSA, ECDSA, and EdDSA. RSA, ECDSA, and EdDSA are the encryption algorithms that can be used to generate keys.
  • Host key. The host key is the key that the server presents to the client to prove its identity.
  • User key. The user key is the key that the client presents to the server to prove its identity.
  • MAC. Message Authentication Code is a secret code agreed upon by the client and the server during SSH negotiations. The MAC is used to verify the integrity of packets sent between the two.
  • Cipher. Ciphers are cryptographic algorithms used to encrypt SSH connections.
  • KEX algorithm. Key Exchange Algorithms are used to securely generate and exchange a shared symmetric key that is being used for packets encryption.