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Hi Dirk,
A simple question: when GeneralSync transmits packets containing calendar and contact info between different devices on a LAN, are the packets encrypted (and hence unreadable by any other device eavesdropping on the LAN)?
Regards,
Martin
A simple question: when GeneralSync transmits packets containing calendar and contact info between different devices on a LAN, are the packets encrypted (and hence unreadable by any other device eavesdropping on the LAN)?
Short answer: Yes.
Long/technical answer: All data connections terminating on other devices are encrypted. GeneralSync currently uses TLS 1.2 with the cipher suite TLS_DHE_RSA_WITH_AES_256_GCM_SHA384, authenticating both ends of the connection directly by their raw keys. For that, it prefers SHA256withRSA but permits some level of degradation for compatibility reasons. For pairing, challenge-response mechanisms utilizing the pair key are used to establish initial trust in the other device's key.
Note that encryption is not a silver bullet: while an eavesdropper cannot see what information you sync, they can still determine that you are using GeneralSync, as well as potentially derive some information regarding your usage patterns (like estimating the number of changes you made while they were listening). That effect is not specific to GeneralSync, though. You will have a similar effect with any tool that exchanges data on a network. So I'd still advise to not connect to networks that contain known attackers 
Thanks!
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