We are committed to ensuring that your information is secure. Our solution architecture is built in such a way that the data is passed via our server in Amazon facilities in the USA and deleted from it immediately at the end of each user session.
The whole s3rsync session (yours and ours) is encrypted via SSL. Even if our servers will be hacked, there is nothing to steal. We do not store your AWS Secret Key at any time. We do not cache it or write it to any local file.
For added protection, you can consider encrypting your data before sending it to any 3rd party online storage solution, S3 or other. Here is a link to Rsync friendly encryption utility's.
We do not sell, trade or distribute your personal information to any party unless we are required by law to do so.