Session Keys (S-ENC and S-MAC)
S-ENC and S-MAC are the two short-lived keys used in a secure channel: one encrypts messages and the other proves they have not been altered.
What is Session Keys (S-ENC and S-MAC)?
Both are derived from a shared secret at the start of a session. GlobalPlatform's Secure Channel Protocols (SCPs) use such keys to protect commands sent to smart cards and eUICCs.