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.cdoc file: what it is and how to open it

CDOC is not a signed but an encrypted container. ASiCE Viewer shows who an older .cdoc file is encrypted for, but the content cannot be decrypted in a browser.

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What is a .cdoc file?

CDOC is the Estonian format for encrypted documents. The sender encrypts the files with the certificate of the recipient's ID-card, and only the recipient can open them, using their ID-card and PIN1 in the DigiDoc4 client.

The older CDOC 1.0 is an XML file whose header shows the recipients' names. The newer CDOC 2.0 is a binary format. Neither can be opened without the recipient's private key – that is the whole point of encryption. So no website, ours included, can show the content of a .cdoc file.

CDOC (.cdoc)
File extension.cdoc, .cdoc2
PurposeEncrypting files for a specific recipient
OpeningIn the DigiDoc4 client with the recipient's ID-card and PIN1
On the webContent cannot be decrypted; CDOC 1.0 shows the recipients

How to open a .cdoc file

  1. Open DigiDoc4

    Insert your ID-card into the reader and start the DigiDoc4 client. Choose the Crypto section on the left.

  2. Select the .cdoc file

    Drag the .cdoc file into the DigiDoc4 window, or double-click it in your file manager.

  3. Decrypt

    Press the decrypt button and enter PIN1. You can then open or save the files.

What ASiCE Viewer shows about a .cdoc file

Drop an older, XML-based CDOC 1.0 file here and we read the recipients' names and the names of the encrypted files from its header. That lets you check whether the file is meant for you before you go looking for a card reader.

The content stays encrypted – neither we nor anyone else but the recipient can see it.

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ASiC-E Viewer for Android

Open signed containers on your phone, even offline. See the signature details and export documents to PDF or Word.

  • Works offline
  • .asice · .bdoc · .edoc · .adoc · .p7s
  • Export to PDF and DOCX
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Questions about .cdoc files

Can a .cdoc file be opened without an ID-card?

An older CDOC 1.0 file can only be decrypted with the ID-card or Digi-ID whose certificate it was encrypted for. For what the newer CDOC 2.0 allows, see the current information on id.ee.

I got a new ID-card – will my old .cdoc file open?

No. CDOC is encrypted with the key of a specific card. Once the card has been replaced or is no longer valid, the file can no longer be opened. That is why CDOC is not suitable for long-term storage.

What is the difference between .cdoc and .asice?

ASICE is a signed container – anyone can read its content, and the signature proves who approved the document. CDOC is an encrypted container – only the recipient can read its content.

Other supported formats