What is the PDC file format?
A .pdc file is a DRM-encrypted document produced by LockLizard Limited's Safeguard PDF Security software. When a publisher uses Safeguard to protect a PDF document, the output is a .pdc file - an opaque, proprietary container that encrypts the original PDF content and enforces access controls at the viewer level.
Unlike a standard PDF, a .pdc file does not begin with the %PDF- header; its bytes are ciphertext from byte zero. It cannot be opened in Adobe Reader, web browsers, or any generic PDF tool - only LockLizard's own software can render it.
To open a .pdc file, the recipient needs two things:
- The free Locklizard Safeguard Viewer (available for Windows, macOS, iOS, and Android, or via a browser-based Web Viewer)
- A valid licence file (
.llv) issued by the document's publisher, which binds the file to the recipient's device or account
DRM controls are set per-document by the publisher and can include:
- Automatic expiry after a specified date or number of views
- Restrictions on printing, copy-paste, and screen capture
- Dynamic watermarking with the viewer's name, email, or IP address rendered at display time
- Locking the document to specific registered devices
.pdc is entirely proprietary to LockLizard's ecosystem. There is no documented public file signature, and the format cannot be interpreted by any third-party PDF library or tool.
Security & safety
RISK: LOWThe .pdc format itself is a controlled, encrypted document and is not a typical malware vector - the real risks are around it. (1) Only install the Safeguard Viewer from locklizard.com; fake "PDC viewer/opener" downloads are a known adware/scam lure. (2) Avoid "PDC to PDF converter" sites - they are scams or DRM-cracking tools that may be illegal to use and often deliver malware. (3) The viewer validates licences online and can apply device locking and dynamic watermarks, so treat a .pdc as monitored, publisher-controlled content. If you can't open it, contact the publisher for the licence (.llv), not a third-party "unlocker".
Format details
in a nutshell- Adobe Photoshop PhotoDeluxe file - Older Adobe PhotoDeluxe used .pdc for its image documents - unrelated to the DRM PDF; opens in legacy PhotoDeluxe only.
- PALMDOC / Palm eBook data - Some Palm/PalmDOC era tools used .pdc for compressed document data - a different, legacy format.
- JSP / web cache fragment - Occasionally seen as a generated/cache fragment from JSP or other web tooling; not a user document.
Programs that open PDC files
Windows1 app
Locklizard Safeguard Secure PDF Viewer
Free Install the viewer, register the licence (.llv) the publisher emailed you, then open the .pdc - it decrypts and displays under the publisher's rules. 
macOS1 app
Locklizard Safeguard Secure PDF Viewer (macOS)
Free Install the macOS Safeguard Viewer, register your .llv licence, then open the .pdc. 
Android1 app
Locklizard Safeguard Viewer (Android)
Free Install the Android viewer, register your licence, then open the .pdc.
Locklizard Safeguard Viewer (iOS)
Free Install the iOS viewer app, register the licence, and open the .pdc on iPhone/iPad.
Locklizard Web Viewer
Free If the publisher enabled web viewing, open the .pdc in a browser via the Safeguard Web Viewer with your credentials - no install needed. Technical details
deep spec| Encoding | Binary AES-encrypted ciphertext; no plaintext PDF content is present anywhere in the file |
| Encryption algorithm | AES at US Government-grade strength; key material is delivered via LockLizard's licence server and stored in the companion .llv licence file |
| DRM licence model | Server-validated; viewer contacts the LockLizard licence server on first open and at intervals to enforce access rules and check revocation |
| Licence binding | Each .pdc is bound to a recipient-specific .llv licence file and can be locked to a registered device or a fixed number of devices |
| Access controls | Per-document controls set by the publisher: view expiry by date or count, print enable/disable, copy-paste disable, screen-capture prevention |
| Dynamic watermarking | Recipient name, email address, date/time, and IP address can be rendered into pages at view time without modifying the encrypted file |
| File signature | No public magic number; file does not start with %PDF- header - the entire content is ciphertext from byte 0 |
| MIME type | application/octet-stream (no format-specific MIME type is registered) |
| Platform support | Windows, macOS, iOS, Android via native Safeguard Viewer apps; browser-based access via LockLizard Web Viewer |
| Source format | Always derived from a PDF; the source PDF's internal compression and structure are preserved before the AES encryption layer is applied |
| Companion file | Requires a .llv licence file issued by the document publisher through the Safeguard Administration System |
| Compression | Inherits the source PDF's internal compression (Flate, JBIG2, JPEG, etc.); the .pdc wrapper adds no additional compression |
| Typical file size | Comparable to the source PDF - tens of KB to tens of MB; the encryption wrapper adds negligible overhead |
| Standard PDF tool compatibility | Zero; Adobe Acrobat, browsers, and all generic PDF libraries cannot open or inspect a .pdc file |
| Publisher administration | Document lifecycle - revocation, expiry changes, device unlocking, user management - is controlled server-side via the Safeguard Administration System web console |
| Released | 2004 (Locklizard Safeguard PDF Security) |
| Latest version | Current Safeguard PDF Security / Safeguard Enterprise releases |
| Specification | www.locklizard.com |
PDC conversions
Community Q&A
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