Yes. All documents and (embedded) signatures are 256 bit AES encrypted before stored on Amazon's Simple Storage Service (S3).
All communications with SignRequest use Secure Sockets Layer (SSL) encrypted endpoints.
Our entire infrastructure is hosted on the highly available and robust architecture of AWS (Amazon Web Services) in Dublin. In the case that a European vendor is essential please contact us to discuss the options.
For more information and our ISO 27001 certification please visit our security page.