An overview of DigiDoc container formats supported by different versions and components of the ID-software can be found on the DigiDoc container format life cycle page. There is also a sample file for each format.
BDOC and ASICE digital signature formats
Nowadays, Estonia has adopted the internationally compatible ASiC-E (.asice, i.e. BDOC-TS or ASiC-E LT) signature format, which is automatically used in updated DigiDoc4 (the extension .asice instead of the former .bdoc). It is worth knowing that the long-term evidential value of LT signatures is ensured with a timestamp based on the RFC 3161 standard and this signature format is preferred in all European Union member states.
Previously, Estonia used the country-specific LT-TM format (.bdoc, i.e. BDOC-TM or ASiC-E LT-TM). The long-term evidential value of LT-TM signatures was ensured by a time-mark based on the RFC 2560 standard.
- You can read more on the development of the BDOC file format in the article BDOC2.1 – New Estonian digital signature standard format.
- BDOC 2.1. Digital Signature Standard EVS 821:2014 (published on 5 June 2014, available from the Estonian Centre for Standardisation).
- BDOC 2.1.2 format specification, .PDF (published in May 2014)
CDOC encrypted document format
.CDOC is an extension used for distinguishing between encrypted DigiDoc files.
The encrypted DigiDoc file format (ENCDOC-XML) is based on the international XML-ENC standard.
CDOC files include an encrypted data file (XML document or another binary file (MS Word, Excel, PDF, RTF, etc), the recipient’s certificate, an encrypted key for decrypting the data file (so-called transport key) and other optional metadata. The data file is encrypted with the AES encryption algorithm using a 128-bit key. Several recipients (potential decrypters) can be added to one encrypted file – to this end, the certificates of all recipients and each recipient’s transport keys for encrypting the data file are added to the CDOC file.
- cdoc4j Java library for working with CDOC files (creation and decryption); cdoc1.0 ja cdoc1.1 are supported.
- Required modifications to CDOC for elliptic curve support, .PDF (published 27th of Sept.2017).
- Encrypted DigiDoc Format Specification, .PDF (published 25th of June 2012).