Software & Apps File Types What Is a DDOC File? How to Open, Edit, & Convert DDOC Files Share Pin Email Print DDOC Files. Lifewire / Tim Fisher File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated February 21, 2019 A file with the DDOC file extension is a DigiDoc Digital Signature file that stores encrypted data used with the DigiDoc software. .DDOC is the file extension used in the first generation DigiDoc format, while the latest version uses .BDOC and stands for a Binary Document file. Encrypted DigiDoc files use the .CDOC suffix instead. These DigiDoc formats were developed by RIA. You can read more about the DDOC, BDOC, and CDOC format used with DigiDoc on their DigiDoc File Formats page. If not a DigiDoc file, your particular DDOC file may be a Digital Mars C, C++, or D macro file. Another possible format for your DDOC file may be a graphic file used with Apple's now-discontinued MacDraw software. Though they look awfully similar, DDOC files have nothing at all to do with ADOC files or Microsoft Word's DOC and DOCX file formats. How to Open a DDOC File DigiDoc is the program used to open DDOC files on Windows, Linux, and macOS. To do that, use the Open signed document button on the program's main window. The DigiDoc software is also used to authenticate government-issued ID cards, so it can both check that a document is signed as well as save documents (like Excel, Word, or PDF files) in this encrypted signature format. Depending on the version of DigiDoc you're using, you may see an alert that reads "The current file is a DigiDoc container that is not supported officially any longer. You are not allowed to add or remove signatures to this container" when you try opening the DDOC file. DigiDoc can open other document formats, too, including not only BDOC, ADOC, and EDOC, but also ASICE, SCE, ASICS, SCS, and PDF. I'm not entirely sure how DDOC files work with them, but if yours isn't a DigiDoc file, then it's probably associated with Digital Mars compilers. MacDraw was a vector drawing application released with Mac computers in 1984. It evolved into MacDraw Pro and then ClarisDraw in 1993, but isn't available for download or purchase anymore. It's probably highly unlikely that your DDOC file has anything to do with MacDraw. Your DDOC could be saved in a format that has nothing to do with any of the formats already mentioned here, in which case a totally different program is required to open it. If you think this may be true for your DDOC file, try opening it with a free text editor to see if there's any identifiable text that can help you understand what program was used to create the file. You can then use that information to research a DDOC viewer or editor. If one program on your computer tries to open DDOC files but shouldn't, or you've accidentally associated these extensions with an unrelated program (like MS Word), changing this default "open with" application is easy. How to Convert a DDOC File A free file converter is normally the way to go for converting one file format to another but I don't know of any converter tools that support any of these DDOC formats. The only other way to convert a file is to use the software that opens it, via its save or export option. This might be possible with DDOC files that are used with Digital Mars software but I don't imagine that's also true for DigiDoc files. Still Can't Open Your File? Like I mentioned in the note at the top of this page, some file formats use file extensions that look like they could be related to each other, like the DOC and DDOC extensions. However, this is usually a misunderstanding of the formats which can lead to troubles when you try opening them. For example, a DOC file is opened in a word processor program and cannot be used with DigiDoc or any other DDOC compatible software. The same is true the other way around, where DDOC files aren't compatible with Microsoft Word programs or other text editors. The same concept can be applied to other similar looking file extensions and their related formats, like DCD files which could be DesignCAD Drawing files or DisCryptor Encrypted Database files. DivX Descriptor files that use the DDC and DDCX file extension is another example. If you don't have a DDOC file, then research the file's real file extension to see which program you need to view, edit, or convert it.