Encryption & Metadata

PDF Encryption

CobaltPdf can password-protect the generated PDF using AES encryption (via PDFsharp). You can restrict individual operations such as printing, copying, and modification independently.

Basic Encryption

using static CobaltPdf.Configuration.PdfGenerationOptions;

var pdf = await renderer
    .WithEncryption(new PdfEncryptionOptions
    {
        UserPassword  = "open-me",     // password to open the document
        OwnerPassword = "admin-secret" // password to override permissions (optional)
    })
    .RenderUrlAsPdfAsync("https://example.com");

pdf.SaveAs("protected.pdf");

If OwnerPassword is omitted, CobaltPdf generates a cryptographically secure random owner password internally.

PdfEncryptionOptions Reference

Property	Type	Default	Description
UserPassword	string	required	Password required to open the document
OwnerPassword	string?	auto-generated	Password to override permission restrictions
AllowPrinting	bool	true	Permit the document to be printed
AllowCopying	bool	false	Permit text and content extraction
AllowModification	bool	false	Permit the document to be modified

Restricting All Permissions

var pdf = await renderer
    .WithEncryption(new PdfEncryptionOptions
    {
        UserPassword     = "view-only",
        AllowPrinting    = false,
        AllowCopying     = false,
        AllowModification = false
    })
    .RenderUrlAsPdfAsync("https://example.com/confidential");

Read-Only with Printing Allowed

var pdf = await renderer
    .WithEncryption(new PdfEncryptionOptions
    {
        UserPassword  = "print-ok",
        AllowPrinting = true,   // printing allowed
        AllowCopying  = false,  // copy/paste blocked
        AllowModification = false
    })
    .RenderUrlAsPdfAsync("https://example.com/report");

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PDF Metadata

PDF metadata is embedded in the document's Information Dictionary and is visible to users through "Document Properties" in most PDF viewers. It also aids search engines and document management systems.

Setting Metadata

var pdf = await renderer
    .WithMetadata(m =>
    {
        m.Title    = "Q4 Financial Report";
        m.Author   = "Alice Smith";
        m.Subject  = "Quarterly earnings summary for Q4 2025";
        m.Keywords = "finance, quarterly, earnings, 2025";
        m.Creator  = "MyApp v2.1";
    })
    .RenderUrlAsPdfAsync("https://example.com/q4-report");

MetadataOptions Reference

Property	Type	Default	Description
Title	string?	null	Document title
Author	string?	null	Author name
Subject	string?	null	Subject or description
Keywords	string?	null	Comma-separated keywords
Creator	string?	null	Application that created the content
Producer	string?	"CobaltPdf"	PDF producer (note: PDFsharp may override this)
CreationDate	DateTime?	null	Creation date. null = current UTC time

Combining Encryption and Metadata

Encryption and metadata can be applied together. CobaltPdf runs both through PDFsharp in a single document pass for efficiency:

var pdf = await renderer
    .WithMetadata(m =>
    {
        m.Title  = "Confidential Contract";
        m.Author = "Legal Department";
    })
    .WithEncryption(new PdfEncryptionOptions
    {
        UserPassword = "contract2025",
        AllowCopying = false
    })
    .RenderUrlAsPdfAsync("https://example.com/contract");