kua-agent
6610acfa44
- Services/PdfRedactText.cs: strip text whose origin falls inside a CoverAnnotation from the page content stream at save time, hooked into PdfBurn.DrawAnnotationsIntoDoc. Fixes edited values staying recoverable by text extraction. - Themes/MMD.xaml replaces all thirteen themes; picker and accent strip removed; no dark mode. - Rename KillerPDF -> MMD PDF across code, resources, packaging and locale strings; new icon. - Remove the upstream author credit and the in-app install button.
63 lines
3.1 KiB
C#
63 lines
3.1 KiB
C#
using System;
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using System.Security.Cryptography.X509Certificates;
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using PdfSharp.Drawing;
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using PdfSharp.Pdf;
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using PdfSharp.Pdf.IO;
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using PdfSharp.Pdf.Signatures;
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namespace MmdPdf.Services.Signing
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{
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/// <summary>
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/// Cryptographic (PAdES / PKCS#7) PDF signing, isolated from the rest of the app. Everything else
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/// in MmdPdf uses PdfSharpCore; this module uses PDFsharp 6.2 (the <c>PdfSharp.*</c> namespace),
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/// and the two coexist without clashing. There are deliberately no WPF or Windows-only types here,
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/// so the whole module ports to Avalonia / Linux / Mac unchanged.
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///
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/// v1 milestone: an invisible-but-valid signature (Adobe still lists it in the Signatures panel),
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/// SHA-256, no timestamp. The .NET Framework build of PDFsharp cannot timestamp; once the plumbing
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/// is validated we swap the default signer for a Bouncy Castle IDigitalSigner to get portable
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/// crypto plus timestamps/LTV. A visible signature appearance comes after that.
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/// </summary>
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internal sealed class PdfSigner
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{
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public sealed record SignInfo(string Reason, string Location, string Contact);
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/// <summary>
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/// Signs <paramref name="inputPath"/> with <paramref name="cert"/> and writes the signed copy
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/// to <paramref name="outputPath"/>. Throws on failure.
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/// </summary>
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public void Sign(string inputPath, string outputPath, X509Certificate2 cert, SignInfo info)
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{
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if (cert is null) throw new ArgumentNullException(nameof(cert));
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if (!cert.HasPrivateKey)
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throw new InvalidOperationException(
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"The selected certificate has no private key, so it cannot sign.");
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// Open the finalized PDF. (NOTE: confirm the exact open-mode enum on first build - PDFsharp
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// 6.2 may want PdfReadAccuracy / a different overload here.)
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using PdfDocument document = PdfReader.Open(inputPath, PdfDocumentOpenMode.Modify);
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var options = new DigitalSignatureOptions
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{
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ContactInfo = info.Contact,
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Location = info.Location,
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Reason = info.Reason,
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// Invisible for v1: a zero rectangle and no AppearanceHandler. If PDFsharp requires a
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// non-null AppearanceHandler, that is the first thing to add (a minimal drawn field).
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Rectangle = new XRect(0, 0, 0, 0),
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};
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// Our own SignedCms-based signer: drives the cert's modern (CNG) key provider, so it
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// works with cloud / token keys (Certum SimplySign) as well as software .pfx keys, where
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// PdfSharpDefaultSigner throws "An internal error occurred". Same IDigitalSigner slot, so a
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// Bouncy Castle variant can later swap in here for portability + timestamps.
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var signer = new KillerCmsSigner(cert);
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// Associates the signer + options with the document; the signature is produced on Save.
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_ = DigitalSignatureHandler.ForDocument(document, signer, options);
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document.Save(outputPath);
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}
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}
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}
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