Tapkey Lock Control Protocol¶

The Tapkey Lock Control Protocol (TLCP) defines how entities within Tapkey communicate with each other.

Examples¶

Trigger Lock¶

The following sequence diagram shows a simplified overview of the execution of a trigger lock command.

sequenceDiagram

    Trust Service->>+Mobile App: Lock ID, KeyU, enc_L(KeyU), enc_L(CertU), enc_L(RCL)
    Mobile App->>-Mobile App: Persist data

    User->>Mobile App: User initiates trigger lock
    activate Mobile App
    Mobile App->>Lock: Connect
    activate Lock
    Lock-->>Mobile App: Hello Message: Lock ID, rclSerialNo, Nonce(C), current timestamp

    opt Sync lock time
        Trust Service->>Lock: Set clock
        Note over Trust Service,Lock: Direct tunnel via HTTPS
    end

    opt Get access log
        Mobile App->>+Lock: Get access log
        Lock-->>-Mobile App: Access log
    end

    Mobile App->>Lock: enc_L(CertU), enc_L(KeyU)
    Mobile App->>Lock: enc_U(CMD)
    Mobile App->>Mobile App: Calculate signature
    Mobile App->>Lock: sig_U(C, KeyU, enc_U(CMD))
    Lock->>Lock: Verify signature
    Lock->>Lock: Execute command
    Lock->>Mobile App: Acknowledgement, Access log
    deactivate Lock
    Mobile App->>Trust Service: Access log
    deactivate Mobile App

Legend

Lock ID $:=$ $l$ ⟶ The lock's identification (ID).

KeyU $:=$ $k_{u}$ ⟶ The user's symmetrical encrypting and signing key, for example, abc123.

CertU $:=$ $c_{u}$ ⟶ The user's certificate.

RCL $:=$ $(r_{1}, r_{2}, r_{3})$ ⟶ The lock's revocation control list.

enc_L $:=$ $E_{l}(x)$ ⟶ Function encrypting parameter $x$ using the lock's master key.

sig_U $:=$ $S_{u}(x)$ ⟶ Function signin $x$ using the user's symmetrical key.