Document Processing Libraries RadPdfProcessing Features Digital Signature Signature Validation

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Validating a Signature

Updated on May 13, 2026

The validation is performed for the current field and, since it strongly depends on the file bytes of the document, against the state of the document at the moment of importing.

The Signature class exposes two methods that allow you to validate a signature:

Method	Description
`Validate()`	Accepts a `SignatureValidationProperties` parameter and validates the signature using those properties. Returns a SignatureValidationResult.
`TryValidate()`	Returns a `bool` indicating whether validation succeeded. The first overload accepts an `out` parameter containing a SignatureValidationResult; the second overload also accepts `SignatureValidationProperties`.

The SignatureValidationProperties class exposes the following properties:

Property	Description
`Chain`	Gets or sets the chain used to validate the certificate that signed the digital signature. Of type X509Chain.
`ChainStatusFlags`	Gets or sets the chain status flags that describe the used signature certificate as invalid. Of type X509ChainStatusFlags.

The validation requires that the stream, from which the document is imported, to be opened. The validation is performed for the current field and against the state of the document at the moment of importing.

PdfProcessing Validate Digital Signature Demo

The following example shows how the validation can be used:

Example: Validate a field

RadFixedDocument document = new PdfFormatProvider().Import(File.OpenRead("file-to-import.pdf"), TimeSpan.FromSeconds(10)); // The stream containing the document

string validationStatus;

//For simplicity, the example handles only the first signature.
SignatureField firstSignatureField = document.AcroForm.FormFields.FirstOrDefault(field => field.FieldType == FormFieldType.Signature) as SignatureField;
if (firstSignatureField != null && firstSignatureField.Signature != null)
{
    SignatureValidationProperties properties = new SignatureValidationProperties();
    System.Security.Cryptography.X509Certificates.X509VerificationFlags verificationFlags = System.Security.Cryptography.X509Certificates.X509VerificationFlags.IgnoreInvalidName;
    properties.Chain.ChainPolicy.VerificationFlags = verificationFlags;

    SignatureValidationResult validationResult;
    if (firstSignatureField.Signature.TryValidate(properties, out validationResult))
    {
        if (!validationResult.IsDocumentModified)
        {
            if (validationResult.IsCertificateValid)
            {
                validationStatus = "Valid";
            }
            else
            {
                validationStatus = "Unknown";
            }
        }
        else
        {
            validationStatus = "Invalid";
        }
    }
    else
    {
        validationStatus = "Invalid";
    }
}
else
{
    validationStatus = "None";
}

To evaluate a certificate as trusted, it must be added to the trusted certificates on your machine.

Validating a Signature

Example: Validate a field

See Also