During operation, an electronic device may provide, to a second electronic device, an invitation to share a digital car key associated with a user of the electronic device and a vehicle, where the invitation includes information for creating another instance of the digital car key on the second electronic device. Then, the electronic device may receive, from the second electronic device, a message accepting the invitation, where the message includes a certificate associated with the other instance of the digital car key on the second electronic device. Moreover, the electronic device may provide, to the second electronic device, an approved version of the certificate with a digital signature of the user. Next, the electronic device may provide, to the computer, an instruction to share the digital car key with a set of electronic devices, which is associated with a second user of the second electronic device.