DigiDoc

DigiDoc (Digital Document) is a family of digital signature- and cryptographic computing file formats utilizing a public key infrastructure. It currently has three generations of sub formats, DDOC- , a later binary based BDOC and currently used ASiC-E format that is supposed to replace the previous generation formats. DigiDoc was created and is developed and maintained by RIA (Riigi Infosüsteemi Amet, Information System Authority of Estonia). The format is used to legally sign and optionally encrypt file(s) like text documents as part of electronic transaction. All operations are done using a national id card, a hardware token, that has a chip with digital PKI certificates to verify a person's signature mathematically. Signed file is a container holding actual signed, unmodified files and hence operation does not require any support from software that created those files. Format container and its signatures can be created using application like qDigiDoc or a web service with user's web browser with signing extension. When an application is used, container is typically exchanged between signing parties as an email attachment until everyone has signed it and have their own complete copy. Web services also utilize identity cards for session authentication using an authentication certificate which is also stored on the id-card. (Wikipedia).