Asymmetric Encryption Configuration

Hi

I am using Spring for configuring an "outbound" interceptor to encrypt the
soap message response from my web service method.

I would like to use "Asymmetric" encryption. My understanding is for this, I
need to use the Client's public key to encrypt the soap message response.
The client will use its private key to de crypt.

With respect to configuring the outbound WSS4J interceptor, I am able to
configure which key (alias) to use ie

<entry key="encryptionUser" value="client" />

I believe the option to configure the WSS4J interceptor for symmetric
encryption is
<entry key="encryptionSymAlgorithm"
value="http://www.w3.org/2001/04/xmlenc#tripledes-cbc" />

However, I would like to configure WSS4J interceptor for *Asymmetric
encryption*. Can you please suggest how I can acheive this.

Thank you.
Pete