Digital signatures are an important security mechanism commonly used to provide evidence related to electronic documents in a broader sense. The notion of trust is fundamental in digital signature applications. We identify and discuss different relevant types of trust. First, content, context and structure are initial conditions for reliable and authentic documents. Second, there is a problem of trustworthy environment for creation and verification of digital signature here we also discuss the need of and options for secure hardware devices. The ultimate aim of this paper is to provide a broader overview of most important issues that those creating and relying on digitally signed documents should be aware of.