Network node for field device data

A field device data network, comprising:

• a network node including circuitry configured to:
• receive first field device data,
• store the first field device data in data blocks,
• receive a data block request from a user device, the data block request including a public key and digital monetary data, wherein the user device is not required to be a predefined party in the network,
• check the digital monetary data, and
• when the check is successful, answer the data block request by encrypting the requested data block directly with the public key received in the data block request, without use of a proxy re-encryption key, and by transmitting the data block encrypted using the public key;
• a field device;
• and
• a user device, wherein
• the field device includes second circuitry configured to transmit first field device data and second field device data to the network node, and
• the user device includes third circuitry configured to transmit a data block request to the network node and to receive in response a requested data block encrypted using the public key of the user device, and to decrypt the received data block encrypted a private key of the user device.

A method for transmitting a data block with field device data, comprising, in a network node:

• receiving first field device data;
• storing the first field device data in data blocks;
• receiving a data block request from a user device, the data block request including a public key and digital monetary data, wherein the user device is not required to be a predefined party in the network;
• checking the digital monetary data;
• encrypting the data block directly with the public key received in the data block request, without use of a proxy re-encryption key, upon successful check of the digital monetary data;
• and
• transmitting the data block encrypted using the public key.