---
title: "Create PAdES B-LT and B-LTA signatures in C# | Nutrient .NET SDK"
canonical_url: "https://www.nutrient.io/guides/dotnet/signatures/digital-signatures/create-pades-b-lt-and-b-lta-signatures/"
md_url: "https://www.nutrient.io/guides/dotnet/signatures/digital-signatures/create-pades-b-lt-and-b-lta-signatures.md"
last_updated: "2026-09-22T00:00:00.000Z"
description: "Learn how to create PAdES B-LT and B-LTA signed PDFs for long-term validation using Nutrient .NET SDK."
---

# Create PAdES B-LT and B-LTA signatures in C#

PDF Advanced Electronic Signatures (PAdES) baseline levels define how much validation evidence is embedded in a signed PDF. B-LT embeds long-term validation material. B-LTA adds a document timestamp that protects that material.

Use PAdES B-LT or B-LTA for archival signing workflows where recipients validate signatures after certificates expire or revocation systems change.

This guide shows how to:

- Configure PAdES B-LT signing

- Configure PAdES B-LTA signing

- Save separate outputs for both baseline levels

PAdES B-LT and B-LTA require timestamp configuration and network access to revocation endpoints. B-LTA also appends a document timestamp after the validation material is embedded.

## Prepare the project

Register the SDK license before running signing operations. For setup details, refer to the [getting started with.NET SDK](https://www.nutrient.io/sdk/dotnet/getting-started.md) guide.

```csharp

using System;
using GdPicture14;

void CheckStatus(GdPictureStatus status, string operation)
{
    if (status!= GdPictureStatus.OK)
    {
        throw new InvalidOperationException($"{operation} failed. Status: {status}");
    }
}

LicenseManager license = new LicenseManager();
license.RegisterKEY(""); // Set your license key

```

## Create a PAdES B-LT signature

Load the PDF, configure the certificate and timestamp authority, select `PAdESBaselineLT`, and apply the signature.

```csharp

using GdPicturePDF bLtPdf = new GdPicturePDF();

CheckStatus(bLtPdf.LoadFromFile(@"input.pdf", false), "LoadFromFile");
CheckStatus(bLtPdf.SetSignatureCertificateFromP12(@"certificate.pfx", "Nutrient answers all your document needs"), "SetSignatureCertificateFromP12");
CheckStatus(bLtPdf.SetSignatureInfo("Nutrient", "PAdES B-LT signature", "Toulouse", "sales@nutrient.io"), "SetSignatureInfo");
CheckStatus(bLtPdf.SetSignatureTimestampInfo("http://timestamp.digicert.com", "", ""), "SetSignatureTimestampInfo");
CheckStatus(bLtPdf.SetSignatureHash(PdfSignatureHash.SHA256), "SetSignatureHash");
CheckStatus(bLtPdf.SetSignaturePAdESLevel(PdfSignaturePAdESLevel.PAdESBaselineLT), "SetSignaturePAdESLevel");
CheckStatus(bLtPdf.ApplySignature(@"signed-b-lt.pdf", PdfSignatureMode.PdfSignatureModeAdobeCADES, true), "ApplySignature");

```

`PAdESBaselineLT` creates a signature with embedded validation material, such as certificates and revocation information.

## Create a PAdES B-LTA signature

Repeat the signing setup and select `PAdESBaselineLTA` for an archival timestamp over the validation material.

```csharp

using GdPicturePDF bLtaPdf = new GdPicturePDF();

CheckStatus(bLtaPdf.LoadFromFile(@"input.pdf", false), "LoadFromFile");
CheckStatus(bLtaPdf.SetSignatureCertificateFromP12(@"certificate.pfx", "Nutrient answers all your document needs"), "SetSignatureCertificateFromP12");
CheckStatus(bLtaPdf.SetSignatureInfo("Nutrient", "PAdES B-LTA signature", "Toulouse", "sales@nutrient.io"), "SetSignatureInfo");
CheckStatus(bLtaPdf.SetSignatureTimestampInfo("http://timestamp.digicert.com", "", ""), "SetSignatureTimestampInfo");
CheckStatus(bLtaPdf.SetSignatureHash(PdfSignatureHash.SHA256), "SetSignatureHash");
CheckStatus(bLtaPdf.SetSignaturePAdESLevel(PdfSignaturePAdESLevel.PAdESBaselineLTA), "SetSignaturePAdESLevel");
CheckStatus(bLtaPdf.ApplySignature(@"signed-b-lta.pdf", PdfSignatureMode.PdfSignatureModeAdobeCADES, true), "ApplySignature");

```

`PAdESBaselineLTA` embeds validation material and appends a document timestamp that protects the resulting evidence.

## Error handling

Check every `GdPictureStatus` value. Failures usually come from certificate chain issues, missing revocation endpoints, blocked OCSP or CRL access, or TSA connection problems.

## Conclusion

This workflow creates PAdES B-LT and B-LTA signed PDFs for long-term and archival validation scenarios.
---

## Related pages

- [Add a digital signature to a PDF in C#](/guides/dotnet/signatures/digital-signatures/add-a-digital-signature.md)
- [Add a document timestamp to a PDF in C#](/guides/dotnet/signatures/digital-signatures/add-document-timestamp-to-pdf.md)
- [Add LTV information to PDF signatures in C#](/guides/dotnet/signatures/digital-signatures/add-ltv-information-to-pdf-signatures.md)
- [Sign PDF documents with a certificate in C#](/guides/dotnet/signatures/digital-signatures/certify-a-document.md)
- [Deferred two-phase PDF signing in C#](/guides/dotnet/signatures/digital-signatures/deferred-two-phase-pdf-signing.md)
- [Create a self-signed certificate with PADES extensions](/guides/dotnet/signatures/digital-signatures/sign-a-docx-as-pdf-ua.md)
- [Create a self-signed certificate with PADES extensions](/guides/dotnet/signatures/digital-signatures/sign-a-pdf-ua-document.md)
- [Sign a PDF with an ECDSA certificate in C#](/guides/dotnet/signatures/digital-signatures/sign-pdf-with-ecdsa-certificate.md)
- [Sign a PDF with PKCS#11 in C#](/guides/dotnet/signatures/digital-signatures/sign-pdf-with-pkcs11.md)