public bool VerifySignature()

Public Function VerifySignature As Boolean

using DevExpress.Pdf;
// ...
using(PdfDocumentSigner documentSigner = new PdfDocumentSigner(stream))
    // Obtain the PKCS#7 signature from the list of `PdfSignatureInfo` objects.
    foreach(var signature in documentSigner.GetSignatureInfo()) {
        var pkcs7 = documentSigner.GetPdfPkcs7Signature(signature.FieldName);
       // Obtain the PKCS#7 signature certificate.
        var certificate = pkcs7.GetSignatureCertificate();
       // Check wheter the signature is valid.
        bool isValid = pkcs7.VerifySignature();
        // Verify the signature certificate info.
        string issuerName = certificate.IssuerName.Name;
        bool isCertificateValid = certificate.Verify();
        // Verify the time of signing.
        var timeStamp = pkcs7.GetTimeStampDate();
        bool isTimeStampValid = pkcs7.VerifyTimeStamp();
    }

Imports DevExpress.Pdf
' ...
Using documentSigner As New PdfDocumentSigner(stream)
    For Each signature In documentSigner.GetSignatureInfo()
       ' Obtain the PKCS#7 signature.
        Dim pkcs7 = documentSigner.GetPdfPkcs7Signature(signature.FieldName)
       ' Obtain the PKCS#7 signature certificate.
        Dim certificate = pkcs7.GetSignatureCertificate()
       ' Check wheter the signature is valid.
        Dim isValid As Boolean = pkcs7.VerifySignature()
        ' Verify the signature certificate info.
        Dim issuerName As String = certificate.IssuerName.Name
        Dim isCertificateValid As Boolean = certificate.Verify()
        ' Verify the time of signing.
        Dim timeStamp = pkcs7.GetTimeStampDate()
        Dim isTimeStampValid As Boolean = pkcs7.VerifyTimeStamp()
    Next signature
End Using