In Estonia, the level of electronic signatures is the highest: digital signatures which are considered by law as equivalent to a handwritten signature. To give digital signatures, you can choose from three tools: ID-card (including digi-ID), mobile-ID and Smart-ID. It's best to use several electronic identification tools in parallel so you don't lose access to your bank accounts, e-services and so on if something happens to one device or tool.
In addition to the signature levels, which are of legal significance, the technical format of the signature may also differ. Currently, the ASiC-e format is used for digital signatures in Estonia: a secure digital signature solution that supports the long-term preservation of documents, is internationally recognised and is well-compatible in the world. All new files signed through DigiDoc4 are automatically assigned the .asice file extension. In the past, the .bdoc format was also used in Estonia. With DigiDoc4, you can still open .bdoc files and add your signatures to them, but the first time you digitally sign a new document, it is automatically created with the .asice file extension. It's worth knowing that if you start signing files that were previously signed by others, you won't be able to choose the signature format yourself: all new signatures must be added to the document in the same format as the existing signatures.
The BDOC-TS or ASiC-E LT or AdES LT signature (container format .asice) is a BDOC signature with a timestamp. Unlike in the case of the LT-TM format (digitally signed files with .bdoc extension), the long-term evidential value is ensured with a timestamp based on the RFC 3161 standard. ASiC-E LT signatures have the best international compatibility. DigiDoc4 automatically uses the .asice format when signing all new documents.
History: Signature formats specific to Estonia
Up to 2014, the signature format DDOC was used in Estonia – it was a signature format specific to Estonia, the drawback of which was poor international compatibility.
A BDOC signature format was created in 2014 with the aim of replacing the currently used DDOC. The benefits of introducing a new format are higher security, the long-term preservation of documents and better international compatibility.
There are two subformats of the BDOC digital signature format, which are technically slightly different. They use different file extensions: .bdoc and .asice to make it easier for a standard user to distinguish them.
The use of the ddoc signature format became undesirable from 2015 and has since disappeared from circulation; a more internationally recognised .asice format is preferred instead of the bdoc signature format.