This is an extension of Use Case No. 3, specializing on non-transferable tickets, e.g. buying and using a public transportation pass. The tickets cannot be used by anyone else, only by the buyer's DID.
All the concepts of use case 3 still apply. The difference lies in the ticket itself, which should now contain a reference to the the user's DID itself, i.e. be formulated in the form of a statement.
- User goes to the government office to get a digitalized ID card, meaning the user gets a digital proof about their name, address, photo, etc. This step is needed only once and can be used for any number of tickets or other use cases afterwards.
- User goes to the ticket office (typically days before using the ticket) to buy a monthly ticket for public transportation. In exchange, the user receives a digital proof of ticket ownership (a statement).
- User goes to the subway for traveling (e.g. from home to university) holding
- a proof of ticket ownership
- indirect proof of control using the previously issued DigitalID
- The inspector at the gate or on the train validates both and decides if the user can enter or not.
- Clerk (delegate of the Government Office)
- Witness for digital ID
- Government Office
- digital ID Authority
- Ticket Seller (delegate of the Public Transportation Company)
- digital ID Inspector
- delegated ticket purchase Witness
- Ticket Inspector (delegate of the Public Transportation Company)
- ticket purchase Inspector
- face Verifier (offline, see later)
- Public Transportation Company
- digital ID Verifier (when buying the ticket)
- ticket Authority
- ticket purchase Verifier
This describes the process of using a DigitalID attached to a DID to convince a third party in person (offline process) that you are in control of a DID without signing anything using your private key.
sequenceDiagram
participant User
participant Clerk
participant TicketSeller
participant TicketInspector
note over User,TicketInspector: Digitalize ID card (useful in other cases as well)
User ->> +Clerk: Request DigitalID<br>(including photo, age, etc evidences)
Clerk ->> +Blockchain: Look up User DID Document via Government Office
Blockchain -->> -Clerk: key information
Clerk ->> -User: DigitalID
note over User,TicketInspector: Visit Ticket Office
User ->> +TicketSeller: Request ticket with evidence<br>(DigitalID photo hash)
TicketSeller ->> +Blockchain: Look up Clerk DID Document via Public Trans. Co.
Blockchain -->> -TicketSeller: key information
TicketSeller -->> -User: Pass for DID with Expiry included
note over User,TicketInspector: Taking on a bus at a stop (maybe days later)
User ->> +TicketInspector: Pass + Photo of Face<br>(via DHT, QR, Bluetooth, etc.)
TicketInspector ->> +User: Look at Face
User -->> -TicketInspector: Face
TicketInspector ->> TicketInspector: verify via Public Trans. Co., comparing faces
TicketInspector -->> -User: You can travel
Note: public transportation often uses entrance gates with automated ticket/pass validation without human inspectors. In other cases (depends heavily on the country) or maybe during a regular supervision on spot, users might still have to prove their face.