Hello! My startup is developing a Desktop application for Windows and macOS for encrypting email in local networks. Email encryption in sending applications is planned to be carried out using the S/MIME protocol. The private key is stored on the user's smartphone (we have a requirement from our customers), and at certain moments we simulate the work of a smart card over the WebSocket protocol. In addition, there are policies requiring constant connection of a smart card. However, unlike Android, the user must manually launch the application each time to sign a letter. Is it possible to make sure that the WebSocket connection does not interrupt in the background? We received many negative reviews from iOS users because of this. Or help us please, what protocol can be used for background emulation of smart card operations?