[Release] GroupDocs.Signature for .NET v26.9 - .NET 10, Post-Quantum Signatures, and Secure Defaults

GroupDocs.Signature Product Family
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Dear GroupDocs customers,
We are pleased to announce the release of GroupDocs.Signature for .NET v26.9.
:hammer_and_wrench: What’s New

  • .NET 10 Support (SIGNATURENET-5938): The main package now targets net462; net6.0; net8.0; net10.0, with a new dedicated GroupDocs.Signature.Net100 package. As announced in 26.6, the netstandard2.1 build is no longer shipped.
  • External Resources Off by Default (SIGNATURENET-5950): Linked images, INCLUDEPICTURE fields, linked pictures, and images and style sheets referenced by SVG images are no longer loaded unless you allow them. Use LoadOptions.WhitelistedResources to allow trusted addresses, or set SkipExternalResources = false for trusted documents.
  • SHA-256 PDF Signatures (SIGNATURENET-5976): New PDF digital signatures use SHA-256 in the adbe.pkcs7.detached format, and HashAlgorithm now selects SHA-384 or SHA-512.
  • Certificate Validity Check (SIGNATURENET-5995): Signing with an expired or not-yet-valid certificate is rejected by default. Set DigitalSignOptions.AllowExpired or AllowNotYetValid to sign anyway; a warning is logged.
  • Post-Quantum Signatures (SIGNATURENET-5996): Word documents can now be signed with ML-DSA certificates on every supported platform.
  • SignatureFont Without System.Drawing (SIGNATURENET-5943): The implicit conversion from System.Drawing.Font is removed from the .NET 6, .NET 8 and .NET 10 builds. Set the SignatureFont properties instead.

Also fixed: Verify now checks PDF digital signatures cryptographically (SIGNATURENET-5978), SubjectName and IssuerName now apply to PDF documents (SIGNATURENET-5997), and SignatureSettings.LogLevel now takes effect (SIGNATURENET-6004), plus 8 more fixes.

:warning: Important: this release changes default behaviour (external resources, PDF hash algorithm, certificate validity and log levels). Please review the release notes before upgrading.
Useful Links

We’d love to hear your feedback! Let us know if you have any questions or feature requests.
Best regards,
The GroupDocs Team