Preparing the WS Provider AS Java for Accepting the Signature 
You can use the following procedure to set up the provider system so that it trusts the signature of the consumer system.
Prerequisites
In both the provider and consumer systems, the option for using signatures and encryption is set (for example, under
SAP NetWeaver Administrator 
SOA Management Application and Scenario Communication Single Service Administration 
).
NoteIf you specify the WSDL URL when creating the logical port of the consumer system, the WSDL automatically sets this option.
End of the note.You know which signature certificate to use for the consumer system (by default, System-key).
NoteIf the consumer system uses CA certificates, you can import the CA certificate instead of the signature certificate.
End of the note.
Procedure
Export the System-key signature certificate of the consumer system from the WebServiceSecurity keystore to a file in the file system.
More information, if the consumer system is an AS Java: Managing Key Storage Views
More information, if the consumer system is an AS ABAP: Maintaining PSEs and Administering Certificates
Import the signature certificate for the consumer system in the keystore view WebServiceSecurity of the provider system.
More information: Managing Key Storage Views