cars

Car registry demo

An imaginary and oversimplified car registry, in which the DMV (department of motor vehicles) keeps track of all cars and their ownership.

Roles

• A car registry owned by the DMV, with user dmv.
  • The dmv approves a mint request of a new car by a car dealer, inserting a new car record into the database.
  • The dmv approves a transfer of ownership between a car owner (seller) to a new car owner (buyer).
• Car dealer, with user dealer.
  • Issues a mint request for a new car, which the dmv must approve.
  • The dealer can then transfer ownership by selling the car to a new owner, say alice, the buyer.
• Owners alice, bob (and dealer)
  • Can own a car.
  • Can transfer ownership of the car they own.
  • Can approve the reception (buying) of a car, and assume ownership of it.

To build:

Build the demo binary:

cd examples/cars

go build

Download and build the orion-server, see instructions here.

To run the demo

Setup and initialization

• Set up the demo directory env var. for example:

export CARS_DEMO_DIR=/tmp/cars-demo

• Generate crypto and config material

./cars generate

• Start the server in another process on the same host (in orion-server/bin dir):

./bdb start --configpath $CARS_DEMO_DIR/config &

• Initialise the database: create carDB, onboard users dmv dealer alice bob

./cars init

Mint a new car

• Mint a new car Issue a car mint request transaction:

./cars mint-request -u dealer -c <car-registration>

for example:

./cars mint-request -u dealer -c RED

Issue a car mint approval transaction:

./cars mint-approve -u dmv -k <mint-request-key>

for example:

./cars mint-approve -u dmv -k mint-request~Y1wBzSDMxYH3C5m5PVi_Tn6sBpZVv-NT0MkHBjsFQME=

• List the car

./cars list-car -u dmv -c RED

./cars list-car -u dealer -c RED

These will fail, as bob has no access and the BLUE car does not exist.

./cars list-car -u bob -c RED

./cars list-car -u dmv -c BLUE

Transfer ownership

• Transfer ownership between a seller (current owner) and a buyer (next owner) with the dmv as a notary.

Issue a transfer ownership multi-sig transaction:

./cars transfer -u dmv -s <seller> -b <buyer> -c <car-registration>

for example:

./cars transfer -u dmv -s dealer -b alice -c RED

This issues a multi-sig transaction between the dealer, alice, and the dmv.

Provenance and proofs

• Provenance

Inspect some provenance information on the car, for example: ./cars list-car -u alice -c RED

./cars list-car -u dmv -c RED --provenance

• Verify Tx evidence (envelope & receipt) against Tx proof

ls $CARS_DEMO_DIR/txs

If a user has the transaction evidence (Tx envelope & Tx receipt), he can obtain a proof that the TX exists in the ledger and verify the proof: ./cars verify-tx -u <user-id> -t <tx-id>

for example, to prove the existence of the car ownership transaction, assume alice gave the Tx evidence to bob:

./cars verify-tx -u bob -t l0c7CvOpuMQjdlH1NAbqtSPzkihr1LN3Kn1eHOg64xs=