Method and system for controlling interconnected devices operating in an untrusted environment

A method for controlling a plurality of devices via a reference device and making the devices cooperate to perform a task, each device being owned by a corresponding owner, each device being equipped with a processing unit with a memory and a communication unit, and adapted to execute operations necessary to perform the task, the memory of each device storing a corresponding set of cryptographic private keys of the owner of the device, a decentralized identifier (DID) of its owner associated with a set of public cryptographic keys respectively corresponding to the private keys, a programmed method of authentication of the other devices and the reference device adapted to run on the processing unit of the device, the sets of public cryptographic keys of the other devices, a set of verifiable data, each verifiable data comprising corresponding operation parameter data values and associated internal rules necessary to perform the task, and verifiable credentials of the owner of the device, the communication units of the devices being adapted to securely communicate with each other via a wireless or wired communication network, the reference device being equipped with a processing module, a memory module and a communication module and adapted to securely communicate with each device communication unit via the wireless or wired communication network, the reference device and the devices being adapted to transfer data using an encryption protocol, the memory module of the reference device storing corresponding set of cryptographic private keys of a reference owner of the reference device, and corresponding decentralized identifier data (DID) associated with a set of public cryptographic keys respectively corresponding to the reference device private keys, and the set of public cryptographic keys of each device of said plurality of devices, the reference device and each device being adapted to digitally sign with their corresponding stored private keys a transfer receipt, and the memory of each device further storing the set of public cryptographic keys of the reference device, wherein

• each transfer of data between any two devices, and between the reference device and any device, is encrypted with a private key according to the encryption protocol, and any receiver of a message transferred according to said encryption protocol authenticates a sender of the received message by decrypting the message with a public key corresponding to the private key of the owner of the sender of the message used for encrypting said message, and in case the message includes a signed transfer receipt, the receiver further verifies whether each signature on the signed transfer receipt is valid;
• each signed transfer receipt sent or received by a device is stored in its memory, and each signed transfer receipt sent or received by the reference device is stored in its memory module;
• each time a first device sends to a second device, via its communication unit, possibly via the reference device, an encrypted message including a signed transfer receipt and indicating an operation involving a use of given operation parameter data values to be executed by the second device as being part of the task, the signed transfer receipt includes the respective DIDs of the first device, the second device and the reference device together with the given operation parameter data values;
• and,
• the second device, upon reception of this message by its communication unit, decrypts the message, executes the operation by using the operation parameter data values included in the signed transfer receipt in the received message and its processing unit removes from the set of its verifiable data stored in its memory selected verifiable data of which operation parameter values match the given operation parameter data values used for executing the operation and stores apart in its memory said selected verifiable data, generates a proof of said removal and storing apart of the selected verifiable data and includes the generated proof into the signed transfer receipt, and the second device further signs via its processing unit the signed transfer receipt in the received decrypted message, and sends via its communication unit to the reference device an encrypted message including said further signed transfer receipt together with said selected verifiable data;
• and
• upon reception by the communication module of the reference device of the encrypted message from the second device including said further signed transfer receipt together with said selected verifiable data, the reference device verifies whether the received proof in the received further signed transfer receipt is valid and whether data of the received selected verifiable data comply with the associated internal rules;
• and
• in case of successful authentication of the respective receiver and sender for any transfer of message between the first device and the second device concerning said operation, and between any one of the first and second devices and the reference device concerning said operation, and successful verification of data content of any transferred message, the reference device further signs and stores in its memory module the transfer receipt signed by the first device and the second device and containing said proof generated by the second device, and sends an encrypted message containing said further signed transfer receipt to the first device and the second device, thereby indicating to said two devices that the operation has been executed;
• and
• upon reception by the communication unit of the second device of said transfer receipt further signed by the reference device, the second device deletes from its memory the selected verifiable data.