Dropshare will only synchronise parts of your upload history to the Dropshare Sync servers. Your connection data or any kind of credentials are not being synchronised and will never leave your device.
The history data will be encrypted on your device using the AES 256 encryption standard, and will only be decrypted on your other devices that run Dropshare (and are signed in for Dropshare Sync). Dropshare Sync does not know your encryption key (which is based on your Dropshare Sync password), and will never be able to decrypt your data.
Preview images and landing pages will, if synchronization is enabled, not be encrypted.
Therefore, in case you forgot your Dropshare Sync credentials, there's no way for us to recover your data. You can easily sign up for another account in case you want to start using Dropshare Sync again.
Additionally, all communication with Dropshare Sync is of course using SSL encryption.