Security best-practices

This document describes how the integrity of software produced by Duende Software is maintained during the software development life cycle.

Data processing

Our products are off-the shelf downloadable developer components. They are not managed services or SaaS - nor do we store, have access to, or process any of our customers’ data or their customers’ data.

Systems access

  • Multiple systems are used in the development life cycle, including GitHub, NuGet, and Microsoft Azure Key Vault.
  • Multi-factor authentication is required for all services mentioned above.
  • Only a limited subset of Duende Software employees act as administrators for each system.

Software development

  • All code is stored in GitHub.
  • Any code added to a project must be added via pull request.
  • At least one other staff member must review a pull request before it can be merged to a release branch.
  • Static code security analysis is performed for every check-in (using GitHub CodeQL).


  • Automated test suites are run on code in every pull request branch.
  • Pull requests cannot be merged if the automated test suite fails.


  • Merging a pull request does not immediately release new features to users, this requires an additional release step.
  • All compiled software packages with associated source are available as GitHub releases.
  • Compiled software libraries (such as Duende IdentityServer) are published to NuGet.
  • Packages must be pushed to NuGet by a Duende Software staff member only after additional validation by the staff member.
  • All NuGet packages are signed with a code signing certificate
    • The private key (RSA 4096 bits) is stored in Azure Key Vault.
    • The private key never leaves Key Vault and the signature process is performed by Key Vault.
    • NuGet will validate the package signature with Duende’s public key to verify they were legitimately built by Duende Software and have not been compromised or tampered with.
    • NuGet client tooling can be configured to accept signed packages only.
  • Once on NuGet, the package is available for end users to update their own solutions.
  • End users still must take explicit action to upgrade after reviewing the package’s release notes.

Vulnerability management process

  • Potential security vulnerabilities can be responsibly disclosed via our contact form.
    • We guarantee to reply within two US business days.
  • All licenses includes a security notification service.
    • Whenever a security vulnerability has been confirmed and fixed, customers will get a private update prior to public release.
  • We will publish an official advisory


IdentityServer has two dependencies:


Duende IdentityServer is a certified implementation of OpenID Connect.

Package Signing

NuGet packages published by Duende are cryptographically signed to ensure their authenticity and integrity. Our certificate is signed by Sectigo, which is a widely trusted certificate authority and installed by default in most environments. This means that in many circumstances, the NuGet tools can validate our packages’ signatures automatically.

However, some environments (notably the dotnet sdk docker image which is sometimes used in build pipelines) do not trust the Sectigo certificate. Typically this isn’t a problem, because NuGet packages distributed by are signed by as the repository in addition to Duende’s signature as the publisher.’s certificate is signed by a different authority that most build pipelines do trust. The NuGet tools will validate packages if they trust either the publisher or the repository.

In the rare circumstance that we distribute a NuGet package not through (and therefore without a repository signature), it might be necessary to add the Sectigo root certificate to NuGet’s code signing certificate bundle. Sectigo’s root certificate is available from Sectigo here.

Trusting the Sectigo certificate

Here is an example of how to configure NuGet to validate a package signed by Duende but not signed by in the docker dotnet sdk image - an environment that does not trust Sectigo by default.

First, get the Sectigo certificate and convert it to PEM format:


openssl pkcs7 -inform DER -outform PEM -in SectigoPublicCodeSigningRootR46.p7c -print_certs -out sectigo.pem

Next, you should validate that the thumprint of the certificate is correct. Bootstrapping trust in a certificate chain can be challenging. Fortunately, most desktop environments already trust this certificate, so you can compare the downloaded certificate’s thumprint to the thumbprint of the certificate on a machine that already trusts it. You should verify this independently, but for your convenience, the thumprint is CC:BB:F9:E1:48:5A:F6:3C:E4:7A:BF:8E:9E:64:8C:25:04:FC:31:9D. You can check the thumbprint of the downloaded certificate with openssl:

openssl x509 -in sectigo.pem -fingerprint -sha1 -noout

Then append that PEM to the certificate bundle at /usr/share/dotnet/sdk/8.0.303/trustedroots/codesignctl.pem:

cat sectigo.pem >> /usr/share/dotnet/sdk/8.0.303/trustedroots/codesignctl.pem

After that, NuGet packages signed by Duende can be successfully verified, even if they are not distributed by

dotnet nuget verify Duende.IdentityServer.7.0.x.nupkg