QUANTUM-COMPUTING SECURE DIGITAL AND PHYSICAL PROOF OF WORK

A computer-implemented method for proof-of-work for generating and validating a block of a blockchain using at least one printing device is disclosed. The printing device is configured for generating at least one digital image depending on a printer control setting. The method comprises the following steps:i) (110) determining a plurality of number strings by solving at least one cryptographic puzzle;ii) (118) selecting one of the number strings of the determined plurality of number strings as mining printer control setting;iii) (120) printing at least one initial digital image (116) comprising a plurality of colored pixels by using the printing device with the selected mining printer control setting (112) and scanning the printed image by using at least one scanning device, thereby generating a mining digital image (122) having a plurality of colored pixels different from the initial digital image (116);iv) (124) comparing the colored pixels of the mining digital image (122) and a task digital image (114) by using at least one processing device, wherein the task digital image (114) comprises a plurality of colored pixels being different from the initial digital image (116).The method comprises repeating steps ii) (118) to iv) (124) until the colored pixels of the mining digital image (122) and the task digital image (114) are found to be identical. In each case in step ii) (118) a different mining printer control setting (112) is selected. The mining printer control setting (112) for which the mining digital image (122) and the task digital image (114) are found to be identical, at least within tolerances, is used as the proof-of-work for generating and validating the block of the blockchain.