internal void OnIncomingError(IncomingMessage message, Exception error)
{
if (Logger.IsDebugEnabled)
{
Logger.Error(this.BuildVerboseErrorMessage("INCOMING", message, error));
}
else
{
Logger.Error("INCOMING_ERROR {0}", error.Message);
}
}
/// <summary>
/// To simplify outbound mail sending, SMTP Server allows you to drop new messages into a pickup folder
/// You don't need to use SmtpClient or some other SMTP client
/// </summary>
public void Send(IncomingMessage envelope, string pickupFolder, DirectAddressCollection senders, MDNStandard.NotificationType notificationType)
{
if (string.IsNullOrEmpty(pickupFolder))
{
throw new ArgumentException("value null or empty", "pickupFolder");
}
if (senders.IsNullOrEmpty())
{
return;
}
foreach (NotificationMessage notification in this.Produce(envelope, senders.AsMailAddresses(), notificationType))
{
string filePath = Path.Combine(pickupFolder, Extensions.CreateUniqueFileName());
notification.Save(filePath);
}
}
internal void UpdateMdn(IncomingMessage message)
{
Debug.Assert(m_settings.HasMdnManager);
using (MdnMonitorClient client = m_settings.MdnMonitor.CreateMdnMonitorClient())
{
var notification = MDNParser.Parse(message.Message);
var disposition = notification.Disposition;
var originalMessageId = notification.OriginalMessageID;
var originalSender = message.Recipients.First().Address;
var originalRecipient = message.Sender.Address;
client.Update(
new Mdn // extract into MdnMonitorParser
{
MessageId = originalMessageId,
Recipient = originalRecipient,
Sender = originalSender,
Status = disposition.Notification.ToString()
});
}
}
/// <summary>
/// Decrypt (optionally) the given message and try to extract signatures
/// </summary>
bool DecryptSignatures(IncomingMessage message, X509Certificate2 certificate, out SignedCms signatures, out MimeEntity payload)
{
MimeEntity decryptedEntity = null;
signatures = null;
payload = null;
if (certificate != null)
{
decryptedEntity = m_cryptographer.DecryptEntity(message.GetEncryptedBytes(m_cryptographer), certificate);
}
else
{
decryptedEntity = message.Message;
}
if (decryptedEntity == null)
{
return false;
}
if (SMIMEStandard.IsContentEnvelopedSignature(decryptedEntity.ParsedContentType))
{
signatures = m_cryptographer.DeserializeEnvelopedSignature(decryptedEntity);
payload = MimeSerializer.Default.Deserialize<MimeEntity>(signatures.ContentInfo.Content);
}
else if (SMIMEStandard.IsContentMultipartSignature(decryptedEntity.ParsedContentType))
{
SignedEntity signedEntity = SignedEntity.Load(decryptedEntity);
signatures = m_cryptographer.DeserializeDetachedSignature(signedEntity);
payload = signedEntity.Content;
}
else
{
throw new AgentException(AgentError.UnsignedMessage);
}
return true;
}
void ValidateRoutingHeaders(IncomingMessage message)
{
if (!message.AreAddressesInRoutingHeaders(message.DomainRecipients))
{
throw new AgentException(AgentError.RecipientMismatch);
}
}
int CountNotificationsToBeSent(IncomingMessage incoming)
{
return m_producer.Produce(incoming).Count();
}
void CollectSignatures(StringBuilder builder, IncomingMessage message)
{
if (!message.HasSignatures)
{
return;
}
SignerInfoCollection allSigners = message.Signatures.SignerInfos;
foreach (SignerInfo signer in allSigners)
{
X509Certificate2 cert = signer.Certificate;
string output = string.Format(
"E/CN={0},ValidFrom={1},ValidTo={2},IssuerName={3},Version={4},Thumbprint={5}",
cert.ExtractEmailNameOrName(),
cert.GetEffectiveDateString(),
cert.GetExpirationDateString(),
cert.Issuer,
cert.Version,
cert.Thumbprint);
builder.Append("CERT:").AppendLine(output);
}
}
/// <summary>
/// Generate external notification messages for failed final destination delivery
/// </summary>
/// <param name="envelope"></param>
/// <param name="recipients">sending failure status for these message recipients</param>
/// <returns>An DSNmessage</returns>
public DSNMessage ProduceFailure(IncomingMessage envelope, DirectAddressCollection recipients)
{
if (envelope == null)
{
throw new ArgumentNullException("envelope");
}
if (string.IsNullOrEmpty(m_settings.ProductName))
{
throw new ArgumentException("reportingAgentName:AgentSettings:ProductName");
}
DSNPerMessage perMessage = new DSNPerMessage(envelope.Sender.Host, envelope.Message.IDValue);
//
// Un-Deliverable recipients
//
List<DSNPerRecipient> dsnPerRecipients = envelope.CreatePerRecipientStatus(recipients.AsMailAddresses()
, m_settings.Text, m_settings.AlwaysAck, DSNStandard.DSNAction.Failed, DSNStandard.DSNStatus.Permanent
, DSNStandard.DSNStatus.DELIVERY_OTHER).ToList();
DSN dsn = new DSN(perMessage, dsnPerRecipients);
//Configure and/or dynamic plus refactor
//TODO: Split messages by domain. See envelope.Recipients[0] below.
return envelope.Message.CreateStatusMessage(new MailAddress("Postmaster@" + envelope.Recipients[0].Host), dsn);
}
/// <summary>
/// Ensure that domain recipients are KNOWN - i.e. registered with the Config System
/// If not, remove them.
/// </summary>
/// <param name="message"></param>
void VerifyDomainRecipientsRegistered(IncomingMessage message)
{
message.EnsureRecipientsCategorizedByDomain(this.SecurityAgent.Domains);
if (!message.HasDomainRecipients)
{
throw new AgentException(AgentError.NoRecipients);
}
DirectAddressCollection recipients = message.DomainRecipients;
if (this.Settings.MaxIncomingDomainRecipients > 0 && recipients.Count > this.Settings.MaxIncomingDomainRecipients)
{
throw new AgentException(AgentError.MaxDomainRecipients);
}
if (!m_settings.HasAddressManager)
{
// Address validation is turned off
return;
}
Address[] resolved = m_configService.GetAddresses(recipients);
if (resolved.IsNullOrEmpty())
{
throw new AgentException(AgentError.NoDomainRecipients);
}
// Remove any addresses that could not be resolved
// Yes, this is currently n^2, but given the typical # of addresses, cost should be insignificant
int i = 0;
while (i < recipients.Count)
{
DirectAddress recipient = recipients[i];
int iAddress = Array.FindIndex<Address>(resolved, x => x.Match(recipient));
if (iAddress >= 0)
{
++i; // Found
recipient.Tag = resolved[iAddress];
}
else
{
recipients.RemoveAt(i);
}
}
}
/// <summary>
/// Decrypts and verifies trust in a signed and encrypted RFC 5322 formatted message, providing a sender and recipient addresses.
/// The provided sender and recipient addresses will be used instead of the header information in the <c>messageText</c>.
/// </summary>
/// <param name="messageText">
/// An RFC 5322 formatted message string.
/// </param>
/// <param name="recipients">
/// A <see cref="DirectAddressCollection"/> instance representing recipient addresses.
/// </param>
/// <param name="sender">
/// An <see cref="DirectAddress"/> instance representing the sender address
/// </param>
/// <returns>
/// An <see cref="IncomingMessage"/> instance with the trust verified decrypted and verified message.
/// </returns>
public IncomingMessage ProcessIncoming(string messageText, DirectAddressCollection recipients, DirectAddress sender)
{
IncomingMessage message = new IncomingMessage(messageText, recipients, sender);
return this.ProcessIncoming(message);
}
/// <summary>
/// Generate notification messages (if any) for this source message
/// </summary>
/// <param name="envelope"></param>
/// <returns>An enumeration of notification messages</returns>
public IEnumerable<NotificationMessage> Produce(IncomingMessage envelope)
{
return this.Produce(envelope, envelope.HasDomainRecipients ? envelope.DomainRecipients.AsMailAddresses() : null, MDNStandard.NotificationType.Processed);
}
protected virtual void SendNotifications(IncomingMessage envelope, DirectAddressCollection senders)
{
if (!m_settings.InternalMessage.HasPickupFolder || !m_settings.Notifications.AutoResponse)
{
return;
}
//
// Its ok if we fail on sending notifications - that should never cause us to not
// deliver the message
//
try
{
if(envelope.Message.IsMDN() || envelope.Message.IsDSN())
{
return;
}
m_notifications.Send(envelope, m_settings.InternalMessage.PickupFolder, senders, MDNStandard.NotificationType.Processed);
if(m_settings.Notifications.GatewayIsDestination && envelope.Message.IsTimelyAndReliable())
{
m_notifications.Send(envelope, m_settings.InternalMessage.PickupFolder, senders, MDNStandard.NotificationType.Dispatched);
}
}
catch (Exception ex)
{
Logger.Error("While sending notification {0}", ex.ToString());
}
}
void Notify(IncomingMessage message, Exception ex)
{
try
{
Action<IncomingMessage, Exception> errorIncoming = ErrorIncoming;
if (errorIncoming != null)
{
errorIncoming(message, ex);
}
}
catch
{
}
}
void SendDeliveryStatus(IEnumerable<Route> router, IncomingMessage envelope, DirectAddressCollection routedRecipients)
{
if (envelope.Message.IsMDN() || envelope.Message.IsDSN())
{
return;
}
DirectAddressCollection undeliveredRecipients = new DirectAddressCollection();
foreach (var route in router)
{
if (route.FailedDelivery)
{
foreach (var routedRecipient in routedRecipients)
{
if(route.AddressType == routedRecipient.Tag as string)
{
undeliveredRecipients.Add(routedRecipient);
}
}
}
}
try
{
m_notifications.SendFailure(envelope, m_settings.InternalMessage.PickupFolder, undeliveredRecipients);
}
catch (Exception ex)
{
Logger.Error("While sending un-secured DSN {0}", ex.Message);
}
}
void PostProcessIncoming(ISmtpMessage message, IncomingMessage envelope)
{
this.CopyMessage(message, m_settings.Incoming);
if (envelope.HasDomainRecipients)
{
DirectAddressCollection routedRecipients = new DirectAddressCollection();
m_router.Route(message, envelope, routedRecipients);
this.SendNotifications(envelope, routedRecipients);
SendDeliveryStatus(m_router, envelope, routedRecipients);
}
//
// Any recipients that were handled by routes are no longer in the DomainRecipients collection (removed)
// Smtp Server should continue process any domain recipients whose delivery were NOT handled by routes
//
if (m_settings.Incoming.EnableRelay && envelope.HasDomainRecipients)
{
this.SendNotifications(envelope, envelope.DomainRecipients);
//
// We only want the incoming message sent to trusted domain recipients
// We are not allowing arbitrary relay
//
message.SetRcptTo(envelope.DomainRecipients);
m_diagnostics.LogEnvelopeHeaders(message);
}
else
{
//
// SMTP Server need not proceed with delivery because we already routed the message to all domain recipients
//
message.Abort();
}
}
private void OnPostProcessIncoming(IncomingMessage message)
{
if (m_settings.HasMdnManager && message.Message.IsMDN())
{
m_monitorService.UpdateMdn(message);
}
}
//-----------------------------
//
// Events
//
//-----------------------------
void Notify(IncomingMessage message, Action<IncomingMessage> eventHandler)
{
//
// exceptions are interpreted as: abort message
//
if (eventHandler != null)
{
eventHandler(message);
}
}
/// <summary>
/// Decrypts and verifies trust in an IncomingMessage instance with signed and encrypted message content.
/// </summary>
/// <param name="message">
/// A <see cref="IncomingMessage"/> instance with signed and encrypted content for decryption and trust verification.
/// </param>
/// <returns>
/// An <see cref="IncomingMessage"/> instance with the trust verified decrypted and verified message.
/// </returns>
public IncomingMessage ProcessIncoming(IncomingMessage message)
{
if (message == null)
{
throw new ArgumentNullException("message");
}
try
{
message.Validate();
this.Notify(message, this.PreProcessIncoming);
this.ProcessMessage(message);
this.Notify(message, this.PostProcessIncoming);
}
catch (Exception error)
{
this.Notify(message, error);
throw; // rethrow error
}
return message;
}
/// <summary>
/// To simplify outbound mail sending, SMTP Server allows you to drop new messages into a pickup folder
/// You don't need to use SmtpClient or some other SMTP client
/// </summary>
public void SendFailure(IncomingMessage envelope, string pickupFolder, DirectAddressCollection recipients)
{
if (string.IsNullOrEmpty(pickupFolder))
{
throw new ArgumentException("value null or empty", "pickupFolder");
}
if (recipients.IsNullOrEmpty())
{
return;
}
if (recipients != null)
{
DSNMessage notification = this.ProduceFailure(envelope, recipients);
string filePath = Path.Combine(pickupFolder, Extensions.CreateUniqueFileName());
notification.Save(filePath);
}
//Or maybe
//
// m_router.Route(message, envelope, routedRecipients);
//
// This would avoid loopback encrypt/decrypt...
//
// ISmtpMessage message
// MessageEnvelope envelope
// DirectAddressCollection routedRecipients, but would use DSN in-reply-to:
//
}
public void TestEndToEndTimelyAndReliableStartMdnMonitor()
{
CleanMessages(m_agent.Settings);
m_agent.Settings.InternalMessage.EnableRelay = true;
m_agent.Settings.Notifications.AutoResponse = true;
m_agent.Settings.Notifications.AlwaysAck = true;
m_agent.Settings.MdnMonitor = new ClientSettings();
m_agent.Settings.MdnMonitor.Url = "http://localhost:6692/MonitorService.svc/Dispositions";
//
// Process loopback messages. Leaves un-encrypted mdns in pickup folder
// Go ahead and pick them up and Process them as if they where being handled
// by the SmtpAgent by way of (IIS)SMTP hand off.
string textMessage = string.Format(TestMessageTimelyAndReliableMissingTo, Guid.NewGuid());
var sendingMessage = LoadMessage(textMessage);
Assert.DoesNotThrow(() => RunEndToEndTest(sendingMessage));
//
// grab the clear text mdns and delete others.
//
bool foundMdns = false;
foreach (var pickupMessage in PickupMessages())
{
string messageText = File.ReadAllText(pickupMessage);
if (messageText.Contains("disposition-notification"))
{
foundMdns = true;
var cdoMessage = LoadMessage(messageText);
Assert.DoesNotThrow(() => RunMdnOutBoundProcessingTest(cdoMessage));
}
}
Assert.True(foundMdns);
//
// Now the messages are encrypted and can be handled
// Processed Mdn's will be recorded by the MdnMonitorService
//
bool foundFiles = false;
foreach (var pickupMessage in PickupMessages())
{
foundFiles = true;
string messageText = File.ReadAllText(pickupMessage);
CDO.Message message = LoadMessage(messageText);
Assert.DoesNotThrow(() => RunMdnInBoundProcessingTest(message));
TestMdnsInProcessedStatus(message, true);
}
Assert.True(foundFiles);
//
// Prepare a Dispatched MDN manually as if this was a edge client
//
//
// Original message needed to create RequestNotification which is
// needed to use the CreateNotificationMessages
//
var mailMessage = MailParser.ParseMessage(textMessage);
mailMessage.RequestNotification();
textMessage = mailMessage.ToString();
var incoming = new IncomingMessage(textMessage);
List<NotificationMessage> notificationMessages = GetNotificationMessages(incoming, MDNStandard.NotificationType.Dispatched);
Assert.True(notificationMessages.Count == 2);
//
// Simulating a destination client sending a dispatched MDN
//
foreach (var notification in notificationMessages)
{
TestMdnTimelyAndReliableExtensionField(notification, true);
var dispatchText = MimeSerializer.Default.Serialize(notification);
CDO.Message message = LoadMessage(dispatchText);
RunEndToEndTest(message);
var duplicateMessage = LoadMessage(dispatchText);
//
// Prove we cannot send duplicate MDNs.
//
RunMdnOutBoundProcessingTest(duplicateMessage);
VerifyOutgoingMessage(duplicateMessage); //Encryted Message
m_agent.ProcessMessage(duplicateMessage); //Decrypts Message
//This proves we could not process the message because it is still encrypted
//Could possibly check to see if it was dropped. This integration test is getting ugly...
VerifyOutgoingMessage(duplicateMessage); //Encryted Message
}
m_agent.Settings.InternalMessage.EnableRelay = false;
}
/// <summary>
/// Generate notification messages (if any) for this source message
/// </summary>
/// <param name="envelope"></param>
/// <param name="senders">sending acks on behalf of these message recipients</param>
/// <param name="notificationType">processed or dispatched</param>
/// <returns>An enumeration of messages</returns>
public IEnumerable<NotificationMessage> Produce(IncomingMessage envelope, IEnumerable<MailAddress> senders, MDNStandard.NotificationType notificationType)
{
if (envelope == null)
{
throw new ArgumentNullException("envelope");
}
if (senders != null && m_settings.AutoResponse)
{
IEnumerable<NotificationMessage> notifications = envelope.CreateAcks(senders, m_settings.ProductName, m_settings.Text, m_settings.AlwaysAck, notificationType);
if (notifications != null)
{
foreach (NotificationMessage notification in notifications)
{
yield return notification;
}
}
}
}
private List<NotificationMessage> GetNotificationMessages(IncomingMessage incoming, MDNStandard.NotificationType notificationType)
{
return incoming.Message.CreateNotificationMessages(
incoming.Recipients.AsMailAddresses(),
sender => Notification.CreateAck
(
new ReportingUserAgent
(
sender.Host
, m_agent.Settings.Notifications.ProductName
)
, m_agent.Settings.Notifications.Text
, notificationType)
).ToList();
}
void ProcessMessage(IncomingMessage message)
{
if (message.Sender == null)
{
throw new AgentException(AgentError.NoSender);
}
if (!message.HasRecipients)
{
throw new AgentException(AgentError.NoRecipients);
}
message.EnsureRecipientsCategorizedByDomain(m_managedDomains);
if (!message.HasDomainRecipients)
{
throw new AgentException(AgentError.NoDomainRecipients);
}
//
// Map each address to its certificates/trust settings
//
this.BindAddresses(message);
//
// Decrypt the message, extract the signature and original content
//
this.DecryptSignedContent(message);
//
// The standard requires that the original message be wrapped to protect headers
//
message.Message = this.UnwrapMessage(message.Message);
this.ValidateRoutingHeaders(message);
//
// Enforce trust requirements, including checking signatures
//
m_trustModel.Enforce(message);
//
// Remove any untrusted recipients...
//
if (message.HasDomainRecipients)
{
message.CategorizeRecipientsByTrust(m_minTrustRequirement);
}
if (!message.HasDomainRecipients)
{
throw new AgentException(AgentError.NoTrustedRecipients);
}
//
// Some recipients may not trust this message. Remove them from the To list to prevent accidental message delivery
//
message.UpdateRoutingHeaders();
}
//---------------------------------------------------
//
// Incoming
//
//---------------------------------------------------
//
// Event handler called by the agent
// Here, if configured, we will verify that addresses are real. We don't always have to do that, especially if
// say we are running as PURELY a gateway. However, if we are set up to e.g. route messages, then...
//
void OnPreProcessIncoming(IncomingMessage message)
{
this.VerifyDomainRecipientsRegistered(message);
}
public void TestMissingMdn()
{
CleanMessages(m_agent.Settings);
m_agent.Settings.InternalMessage.EnableRelay = true;
m_agent.Settings.Notifications.AutoResponse = true;
m_agent.Settings.Notifications.AlwaysAck = true;
m_agent.Settings.MdnMonitor = new ClientSettings();
m_agent.Settings.MdnMonitor.Url = "http://localhost:6692/MonitorService.svc/Dispositions";
string textMessage = string.Format(TestMessageTimelyAndReliableMissingTo, Guid.NewGuid());
//
// RequestNotification needed to use the CreateNotificationMessages
//
var mailMessage = MailParser.ParseMessage(textMessage);
mailMessage.RequestNotification();
textMessage = mailMessage.ToString();
var incoming = new IncomingMessage(textMessage);
List<NotificationMessage> notificationMessages = GetNotificationMessages(incoming, MDNStandard.NotificationType.Processed);
Assert.True(notificationMessages.Count == 2);
RunMdnProcessingForMissingStart(notificationMessages);
notificationMessages = GetNotificationMessages(incoming, MDNStandard.NotificationType.Dispatched);
Assert.True(notificationMessages.Count == 2);
RunMdnProcessingForMissingStart(notificationMessages);
notificationMessages = GetNotificationMessages(incoming, MDNStandard.NotificationType.Failed);
Assert.True(notificationMessages.Count == 2);
RunMdnProcessingForMissingStart(notificationMessages);
notificationMessages = GetNotificationMessages(incoming, MDNStandard.NotificationType.Displayed); //No currently using.
Assert.True(notificationMessages.Count == 2);
RunMdnProcessingForMissingStart(notificationMessages);
notificationMessages = GetNotificationMessages(incoming, MDNStandard.NotificationType.Deleted); //No currently using.
Assert.True(notificationMessages.Count == 2);
RunMdnProcessingForMissingStart(notificationMessages);
m_agent.Settings.InternalMessage.EnableRelay = false;
}
void BindAddresses(IncomingMessage message)
{
//
// Bind each recpient's certs and trust settings
//
DirectAddressCollection recipients = message.DomainRecipients;
for (int i = 0, count = recipients.Count; i < count; ++i)
{
DirectAddress recipient = recipients[i];
recipient.Certificates = this.ResolvePrivateCerts(recipient, m_encryptionEnabled);
recipient.TrustAnchors = m_trustAnchors.IncomingAnchors.GetCertificates(recipient);
}
}
internal void ProcessEndToEnd(SmtpAgent agent, Message msg, out OutgoingMessage outgoing, out IncomingMessage incoming)
{
outgoing = agent.SecurityAgent.ProcessOutgoing(new MessageEnvelope(msg));
incoming = agent.SecurityAgent.ProcessIncoming(new MessageEnvelope(outgoing.SerializeMessage()));
}
void DecryptSignedContent(IncomingMessage message)
{
SignedCms signatures = null;
MimeEntity payload = null;
bool success = false;
if (m_encryptionEnabled)
{
//
// This can be optimized for multiple private keys and recipients where the same certs
// are shared across recipients (org certs). But we will start with the easy to understand simple version
//
// Decrypt and parse message body into a signature entity - the envelope that contains our data + signature
// If we fail to decrypt for any recipient, we are going to treat the message as possibly compromised and reject
// it entirely
//
foreach(DirectAddress recipient in message.DomainRecipients)
{
success = false;
signatures = null;
payload = null;
success = this.DecryptSignedContent(message, recipient, out signatures, out payload);
if (!success)
{
// Any failures.. stop immediately. If we could not decrypt the message for any recipient,
// then the message is suspicious and is rejected
break;
}
}
}
else
{
success = this.DecryptSignatures(message, null, out signatures, out payload);
}
if (!success)
{
throw new AgentException(AgentError.InvalidEncryption);
}
if (signatures == null || payload == null)
{
throw new AgentException(AgentError.UntrustedMessage);
}
message.Signatures = signatures;
//
// Alter body to contain actual content. Also clean up mime headers on the message that were there to support
// signatures etc
//
HeaderCollection headers = message.Message.Headers;
message.Message.Headers = headers.SelectNonMimeHeaders();
message.Message.UpdateBody(payload); // this will merge in content + content specific mime headers
}
bool DecryptSignedContent(IncomingMessage message, DirectAddress recipient, out SignedCms signatures, out MimeEntity payload)
{
signatures = null;
payload = null;
foreach (X509Certificate2 cert in recipient.Certificates)
{
try
{
if (this.DecryptSignatures(message, cert, out signatures, out payload))
{
// Decrypted and extracted signatures successfully
return true;
}
}
catch(Exception ex)
{
this.Notify(message, ex);
}
}
return false;
}
MessageSignature FindTrustedSignature(IncomingMessage message, MailAddress recipient, X509Certificate2Collection anchors)
{
DirectAddress sender = message.Sender;
MessageSignatureCollection signatures = message.SenderSignatures;
MessageSignature lastTrustedSignature = null;
foreach (MessageSignature signature in signatures)
{
bool certTrustedAndInPolicy =
(m_certChainValidator.IsTrustedCertificate(signature.Certificate, anchors) &&
signature.CheckSignature());
if (certTrustedAndInPolicy && recipient != null)
{
certTrustedAndInPolicy = IsCertPolicyCompliant(recipient, signature.Certificate);
}
if (certTrustedAndInPolicy)
{
if (!sender.HasCertificates)
{
// Can't really check thumbprints etc. So, this is about as good as its going to get
return signature;
}
if (signature.CheckThumbprint(sender))
{
return signature;
}
//
// We'll save this guy, but keep looking for a signer whose thumbprint we can verify
// If we can't find one, we'll use the last trusted signer we found.. and just mark the recipient's trust
// enforcement status as Success_ThumbprintMismatch
//
lastTrustedSignature = signature;
}
}
return lastTrustedSignature;
}