3.1.4.1 One-time Password (OTP) Event
An OTP event outside of the scope of this specification (for example, human interaction) triggers the start of the trust agreement process. When the trigger event occurs, the service MUST initiate the process as follows:
The device and control point MUST terminate any ongoing DTAG process, discarding all locally saved OTPs, nonces, endpoint identifiers, and certificates.
The device and control point MUST acquire and locally save the endpoint identifier (in other words, _DeviceID and _HostID, respectively).
The device and control point MUST acquire and locally save the certificate (in other words, _DeviceCertificate and _HostCertificate, respectively).
The device and control point MUST acquire and locally save the OTP, and generate the substrings, as described in section 3.1.1.
The device and control point MUST change TrustState from 0 (Idle) to 1 (Exchanging), as described in section 3.1.1.