Abstract: A banknote includes a security element with a processor and a memory. A private cryptographic key of an asymmetric key pair of the banknote is stored in a protected memory area of the memory. The asymmetric key pair is assigned to a banknote-specific blockchain address in a blockchain. A payment method executed with the banknote includes receiving a payment request for a payment with the banknote in the form of a transaction of an amount to be paid from the blockchain address of the banknote to a blockchain address of a payee, signing a transaction approval with the private cryptographic key of the banknote, and sending the signed transaction approval.

Abstract: The method includes creating a signed output instruction for outputting a vehicle certificate, having a data record characterising the vehicle, using the blockchain, in the case of a valid signature, receiving the vehicle certificate, outputting the vehicle certificate, wherein the output vehicle certificate includes a machine-readable code, wherein the machine-readable code includes a private cryptographic key of an asymmetric key pair, wherein a public cryptographic key of the asymmetric key pair is identified in the blockchain as a check value for checking a signature of a read request for reading vehicle data of the vehicle certificate from the blockchain.