Is RSAPKCS1SignatureDeformatter supported?

From: Mark Shasby (mark_at_shasby.com)
Date: 06/25/04 

Date: Fri, 25 Jun 2004 15:27:29 +0100

Hello,
   I am trying to use RSAPKCS1SignatureDeformatter.VerifySignature() but am
getting a System.NotSupportedException, Additional information:
EncryptValue. I know that RSA.EncryptValue() isn't supported but is the
downstream effect that AsymmetricSignatureDeformatter isn't either? That
seems a bit odd as there are examples of its use around so it must work for
someone?

  Can anyone explain how to get round this or paste some code that IS
working please? 

--
RSAPKCS1SignatureDeformatter asd = new RSAPKCS1SignatureDeformatter(rsaKey);
asd.SetHashAlgorithm("MD5");
asd.VerifySignature(hash, signature);
--