EncryptedKey as KeyInfo in Signature

Hi!

I have successfully set up a web service and secured it using xml encryption and signature (client authentication). Calling it from within our company-internal tool works fine, using soapUI (4.5.1) however fails. In my server logs I have compared the two requests and found one main difference: the keyInfo of the signature

Successful request:

<xenc:EncryptedKey Id="id-of-encryptedKey">
...
</xenc:EncryptedKey>
<ds:Signature>
 ...
 <ds:KeyInfo>
  <wsse:SecurityTokenReference wsu:Id="str-id">
   <wsse:Reference URI="id-of-encryptedKey" ValueType="http://docs.oasis-open.org/wss/oasis-wss-soap-message-security-1.1#EncryptedKey" />
  </wsse:SecurityTokenReference>
 </ds:KeyInfo>
</ds:Signature>

Failed request:

<ds:Signature>
 ...
 <ds:KeyInfo Id="ki-id">
  <wsse:SecurityTokenReference xmlns:wsse11="http://docs.oasis-open.org/wss/oasis-wss-wssecurity-secext-1.1.xsd" wsse11:TokenType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-x509-token-profile-1.0#X509PKIPathv1" wsu:Id="STR-633098343BA81AD4B5139833260383278">
   <wsse:Reference URI="id-of-binarysecuritytoken" ValueType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-x509-token-profile-1.0#X509PKIPathv1" />
  </wsse:SecurityTokenReference>
 </ds:KeyInfo>
</ds:Signature>
<xenc:EncryptedKey xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" Id="ek-id">
 ...
</xenc:EncryptedKey>

Is there any possibility to set an encrypted key as the "Key Identifier Type" for a signature in soapUI?

Thanks in advance.

Cheers,
joe