A method of printing a document (10) stored at a home computing system (5) on a printer (9) of a remote computing system, the home and remote computing system including a home trusted print proxy (HTPP) (3) and a remote trusted print proxy (RTPP) (2), respectively, which are configured to be able to establish communication via a communications link, in which the printer (9) includes a digital identification device (1) configured to provide a printer public key of a cryptographic public key/private key pair and the RTPP (2) is configured to supply a one time token on request, the method including the steps of using a mobile device (4) to interrogate the RTPP (2) and printer (9) to obtain a one time token and the printer public key using the mobile device (4) to transmit to the home computing system (5) a print request including the one time token and printer public and identification of the document (10) to be printed establishing a secure communications channel between the home and remote computing system via at least the HTPP and RTPP the home computing system (5) transmitting the document encrypted by the printer public key to the printer (9) via the secure communications channel and the printer (9) decrypting the encrypted document and initiating printing of the document only if the mobile device is in communication with the printer (9).