Abstract: A method of verifying a user transaction at a blockchain node is provided, the method including receiving at a communication device information provided by a user in a user transaction, generating a message in dependence on the received information and signing the generated message with a private key of a public-private key pair. The method including transmitting the signed message to a server, calling an execution function for executing code of the execution function, the execution function being for verifying that a public key of the public-private key pair matches the private key with which the message was signed, and passing the signed message to the execution function, executing the code to determine whether the signed message was signed with the private key matching the public key, and, based on the determination, verifying the user transaction so as to permit the user transaction to be recorded at a blockchain node.

Abstract: Roughly described, a method of recording a change of authorization state of one or more authorization agents, the method comprising: establishing a copy of a blockchain ledger at each of a plurality of blockchain nodes, wherein each of the blockchain nodes is associated with a different controlling entity; providing a public key/private key pair for a first of the blockchain nodes; receiving, from the communication device, a first message comprising: first data indicative of a change of authorization state of a first authorization agent associated with the first controlling entity, the first data being encrypted; and a digital signature based on the blockchain ledger and the private key; authenticating the message using the public key; adding a block to the blockchain ledger based on the first message, thereby to generate a new blockchain ledger that records the change of authorization state of the first authorization agent.

Abstract: A method of verifying a user transaction at a blockchain node is provided, the method including receiving at a communication device information provided by a user in a user transaction, generating a message in dependence on the received information and signing the generated message with a private key of a public-private key pair. The method including transmitting the signed message to a server, calling an execution function for executing code of the execution function, the execution function being for verifying that a public key of the public-private key pair matches the private key with which the message was signed, and passing the signed message to the execution function, executing the code to determine whether the signed message was signed with the private key matching the public key, and, based on the determination, verifying the user transaction so as to permit the user transaction to be recorded at a blockchain node.

Abstract: Roughly described, a method of recording a change of authorisation state of one or more authorisation agents, the method comprising: establishing a copy of a blockchain ledger at each of a plurality of blockchain nodes, wherein each of the blockchain nodes is associated with a different controlling entity; providing a public key/private key pair for a first of the blockchain nodes; receiving, from the communication device, a first message comprising: first data indicative of a change of authorisation state of a first authorisation agent associated with the first controlling entity, the first data being encrypted; and a digital signature based on the blockchain ledger and the private key; authenticating the message using the public key; adding a block to the blockchain ledger based on the first message, thereby to generate a new blockchain ledger that records the change of authorisation state of the first authorisation agent.