DigiDoc is a universal system for giving, processing and verifying digital signatures created by AS Sertifitseerimiskeskus. It can be connected to any existing or new software, but its components are also a stand-alone client program and web portal.

These are the components of DigiDoc:

• client program. DigiDoc Client is available to anybody to download for free. Anyone can use it to verify digital signatures or, if you have an Estonian ID card and smart card reader, also to give digital signatures.
• web portal. The portal is located at http://digidoc.sk.ee and is available to all ID card holders free of charge. Its functions are similar to the client program - you can use it to give and verify digital signatures. In addition, you can use it to have a document signed by a number of people. With a few clicks of the mouse, you designate the people whose signatures you need on the document, and they can all sign it in the same portal. Every user has a directory of his or her documents which no one else sees but where anyone can send documents to be signed by you.
• file format. DigiDoc specifies the file format of storing a digital signature and other technical data in a container file, together with the original file that was signed. All DigiDoc-enabled programs must support this format, and it must be possible to export files from all the programs into standalone files, to be verified with the standalone DigiDoc Client.
• software library. The DigiDoc library is available to all developers as a program library in C and as a Windows COM component. It can be connected to any existing or new software. For example, you could add DigiDoc support to accounting software, document management system, web/intranet applications etc.