A blockchain verification method, the blockchain verification method performed by a primary blockchain management device and a secondary blockchain initiation device: - sending by the secondary blockchain initiation device one or more smart contract creation transactions to the primary blockchain management device which manages a primary blockchain, the primary blockchain being a public blockchain, the smart contract creation transaction comprising a smart contract for performing verification of an action on a secondary blockchain, the secondary blockchain being a private blockchain different from the primary blockchain, the primary blockchain management device being configured to publish the smart contract in a block of the primary blockchain, - performing by the secondary blockchain initiation device the action on the secondary blockchain - generating by the secondary blockchain initiation device activation transaction comprising at least a blockchain identifier of the secondary blockchain, information relating to the action, and an identifier of the smart contract on the primary blockchain, - sending by the secondary blockchain initiation device the activation transaction to the primary blockchain management device which manages the primary blockchain, the primary blockchain management device executes the smart contract based on input in the activation transaction generating a result, and publishes the result on the primary blockchain, wherein the action performed on the secondary blockchain is the creation of the secondary blockchain, and the smart contract is configured to authenticate the activation transaction and to publish an indication of said authentication thus indicating the valid creation of the secondary blockchain, and the method further comprising before the performing step: - receiving by the secondary blockchain initiation device a request to create the secondary blockchain - obtaining by the secondary blockchain initiation device the blockchain identifier for the secondary blockchain, and wherein the action performed on the secondary blockchain further comprises: generating by the secondary blockchain device an initiation message comprising at least the blockchain identifier for the secondary blockchain and sending the initiation message to multiple secondary blockchain management devices for starting management of the secondary blockchain. - sending by the secondary blockchain initiation device one or more smart contract creation transactions to the primary blockchain management device which manages a primary blockchain, the primary blockchain being a public blockchain, the smart contract creation transaction comprising a smart contract for performing verification of an action on a secondary blockchain, the secondary blockchain being a private blockchain different from the primary blockchain, the primary blockchain management device being configured to publish the smart contract in a block of the primary blockchain, - performing by the secondary blockchain initiation device the action on the secondary blockchain - generating by the secondary blockchain initiation device activation transaction comprising at least a blockchain identifier of the secondary blockchain, information relating to the action, and an identifier of the smart contract on the primary blockchain, - sending by the secondary blockchain initiation device the activation transaction to the primary blockchain management device which manages the primary blockchain, the primary blockchain management device executes the smart contract based on input in the activation transaction generating a result, and publishes the result on the primary blockchain, - receiving by the secondary blockchain initiation device a request to create the secondary blockchain - obtaining by the secondary blockchain initiation device the blockchain identifier for the secondary blockchain, and wherein the action performed on the secondary blockchain further comprises: generating by the secondary blockchain device an initiation message comprising at least the blockchain identifier for the secondary blockchain and sending the initiation message to multiple secondary blockchain management devices for starting management of the secondary blockchain.