"Object reference not set to an instance of an object."

Apr 21, 2011 at 10:22 AM

Hi,

I'm decrypting TLS packages which captured under lync2010 and encounted a exception "Object reference not set to an instance of an object". The detail:

Computing ServerIV for next application data
Exception: Object reference not set to an instance of an object.   at SSLDecryptionExpert.AppDataDecryption.LogApplicationDataDetails(String sourceIP, CipherSuiteInfo cipherSuite)

   at SSLDecryptionExpert.AppDataDecryption.DecryptSslApplicationData(String sourceIP, CipherSuiteInfo cipherSuite)
Exception: Object reference not set to an instance of an object.   at System.Security.Cryptography.HMAC.InitializeKey(Byte[] key)

   at System.Security.Cryptography.HMAC.set_Key(Byte[] value)

   at SSLDecryptionExpert.AppDataDecryption.VerifyMacValueTLS(CipherSuiteInfo cipherSuite, String sourceIP)

   at SSLDecryptionExpert.AppDataDecryption.VerifyMacValue(CipherSuiteInfo cipherSuite, String sourceIP)

   at SSLDecryptionExpert.AppDataDecryption.DecryptSslApplicationData(String sourceIP, CipherSuiteInfo cipherSuite)

   at SSLDecryptionExpert.SSLDecryption.DecryptApplicationData(Int32[] value, String sourceIP)

   at SSLDecryptionExpert.SSLDecryption.ParsedFrameInformation(IntPtr parsedFrame, UInt32& frameNumber, Boolean& isKeyBlockComputed, Boolean& decryptedAppDataPacket, Boolean& exitOnError, NMFilters filter)

   at SSLDecryptionExpert.SSLDecryption.StartDecryption(Dictionary`2 property, String& decryptionResult)

   at SSLDecryptionExpert.SSLDecryption.SslDecryptCapture(Dictionary`2 property, String& decryptionResult)

-.-.-.-.-.-.- SSL Decryption Log Ends-.-.-.-.-.-.-

Can somebody help me to fix it?

Thanks

Ruofeng Wang

May 16, 2011 at 2:48 PM

It's hard to say for certain without seeing the trace or full log.  But my guess is that the conversation you chose doesn't have a full SLL/TLS conversation.  The Help for the expert has an example of the handshake you should see in the trace.  You should check to see if it's matches the traffic mentioned in the documentation.

Thanks,

Paul