Affecto.Pdf.Toolkit.CertificateHelper.FindDigitalSignatureCertificates C# (CSharp) Method

        private static X509Certificate2Collection FindDigitalSignatureCertificates(X509Store x509Store)
        {
            X509Certificate2Collection certificates = x509Store.Certificates.Find(X509FindType.FindByKeyUsage, "nonRepudiation", true);
            if (certificates.Count == 0)
            {
                throw new DigitalSignatureCertificateNotFoundException("No certificate with key usage 'nonRepudiation' found.");
            }

            return certificates;
        }