# OFD documents SumatraPDF opens [OFD](https://fileformats.dev/ofd) (`.ofd`), the Chinese fixed-layout document format (GB/T 33190) used for e-invoices and government documents, and checks its signatures. This page lists what works and how it compares with other OFD software. **Available in [pre-release 3.7](https://www.sumatrapdfreader.org/prerelease).** **Open an `.ofd` file like a PDF**: double-click it, drag it onto the window or use **File → Open**. At a glance: - **Pages:** text, paths, images, templates, annotations, patterns, gradients (including mesh gradients) and signature seals are drawn natively, with no conversion to PDF. - **Packages:** an OFD with several documents shows all of them in order, with a bookmark for each. - **Encrypted OFD:** a password-encrypted package (GM/T 0099) asks for the password, as an encrypted PDF does. - **Text:** select, copy and [find text](Finding-text.md); embedded fonts keep their original characters. - **Links and attachments:** click links to other pages or to web sites; attachments are listed under the bookmarks and open like [PDF attachments](Save-PDF-attachments.md). - **Signatures:** the signature bar and the **Signatures** view show whether each signature is valid, as for [signed PDFs](Verify-PDF-signature.md). - **Convert:** **Convert to PDF** keeps text and vector graphics; **Convert PDF to Images** renders OFD pages too. - **Printing:** [print](Printing.md) any pages. - **File Explorer:** the installer registers `.ofd` for Open With and adds previews and thumbnails. ## Open an OFD file - Double-click an `.ofd` file once SumatraPDF is registered for it, or right-click → **Open with → SumatraPDF**. - An OFD renamed to `.zip`, or attached to a PDF as `.zip`, still opens as OFD. - For a password-encrypted OFD, type the password when asked, or pass it with `-pwd`. A package encrypted for a certificate (it needs the recipient's private key) can't be opened. - The bookmarks sidebar shows the document's outline. For a package of several documents it shows one entry per document, with that document's outline under it. Note: missing fonts are replaced, and a broken image or template is skipped without losing the rest of the page. ## Check OFD signatures Opening a signed OFD checks its signatures in the background. The bar above the document says whether they are valid. Click **Signature Panel** for the list, and open a signature for its details. SumatraPDF checks electronic seals (SES, GM/T 0031 v1 and v4, GB/T 38540) and GB/T 35275 digital signatures that use SM2 and SM3: - the files the signature protects still have the digests it recorded - `Signature.xml` matches the hash inside the signature - the signature matches the signer's certificate, and the certificate was valid at the signature time - the signer's certificate chains to a trusted root A package with integrity protection (GM/T 0099, `OFDEntries.xml`) shows it as one more entry. It is invalid when a file was added to the package or removed from it after it was protected. Results: - **Valid:** the document is unchanged and the signer's certificate chains to a trusted root. - **Invalid:** a signed file was changed or removed, a file was added to a protected package, or the signature doesn't match the certificate. - **Validity unknown:** the document is unchanged, but the certificate doesn't chain to a trusted root. A signature without a certificate, or with an unsupported algorithm, can't be checked either. ## Trust OFD signers Windows doesn't check SM2 certificates, so SumatraPDF does: a signer is trusted when its certificate chains, through certificates in the Windows **Intermediate Certification Authorities** store, to a certificate in the Windows **Trusted Root Certification Authorities** store or in the `OfdTrustedCertificates` advanced setting. To trust a CA without adding it to Windows: 1. Open **Settings → Advanced Settings...** 2. Set `OfdTrustedCertificates` to the path of the CA's certificate file, DER or PEM. Separate several paths with spaces and quote paths that contain spaces: `OfdTrustedCertificates = "C:/certs/my ca.pem" C:/certs/other.cer` 3. Reopen the document. Note: a seal drawn on the page proves nothing by itself. Check the status in the bar or the Signatures view. ## Compare with other OFD software | | SumatraPDF | [ofdrw](https://github.com/ofdrw/ofdrw) | [ofdrw-viewer](https://github.com/ofdrw/ofdrw-viewer) | [ofd.js](https://github.com/DLTech21/ofd.js) | | ---------------------------------------- | ----------------------- | --------------------------------------- | ----------------------------------------------------- | -------------------------------------------- | | What it is | Windows document viewer | Java library | HTML5 reader, rendering engine, command-line tool | JavaScript rendering library | | License | GPLv3 | MIT | MIT | Apache-2.0 | | View and print | ✓ | via conversion to PDF or images | ✓ | renders in a web page | | Viewer with bookmarks and text search | ✓ | | ✓ | | | Encrypted OFD (GM/T 0099) | ✓ decrypt (password) | ✓ encrypt | ✓ decrypt | | | Verify SM2 / SM3 signatures | ✓ | ✓ | ✓ | | | Certificate chain and trusted roots | ✓ | | ✓ | | | Detect files added after signing | ✓ | | ✓ | | | Create, edit, sign, merge | | ✓ | | | | Convert PDF to OFD, OFD to PDF or images | OFD to PDF or images | ✓ | OFD to images | | An empty cell means the project doesn't document the feature. Popular desktop readers in China, all closed source and free to use: - **数科OFD阅读器** (Suwell, [ofd.cn](https://www.ofd.cn/)): Windows and Linux; views, prints and verifies electronic seals, saves as PDF or images. - **福昕OFD阅读器** (Foxit OFD Reader): desktop and mobile; views, annotates, shows the outline and prints. - **WPS Office**: opens OFD on Windows (2021 update and later), Android and iOS; views, annotates and saves as PDF. ## Tips - Use SumatraPDF to read and print OFD invoices without installing a dedicated OFD reader. - Open a signature's details to see which file was changed when a signature is invalid. - Add your CA's certificate to `OfdTrustedCertificates` so its signatures show as valid. - Use ofdrw to create, sign or edit OFD files. - If a page doesn't look right, [report it](How-to-submit-bug-reports.md) with the `.ofd` file. ## What SumatraPDF doesn't do - edit, create or sign OFD files, or convert PDF to OFD - open packages encrypted for a certificate - check signature timestamps - annotate OFD files ## See also - [Supported document formats](Supported-document-formats.md): every format SumatraPDF opens. - [Verify a PDF signature](Verify-PDF-signature.md): the signature bar and Signatures view, for PDFs. - [Advanced settings](Advanced-options-settings.md): `OfdTrustedCertificates` and the other settings. - [Printing](Printing.md): print options.