Preparing the WS Provider AS ABAP 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.
In both the provider and consumer systems, the option Signature & Encryption (Asymmetric Binding) has been selected, for example, in the SOA Manager (transaction SOAMANAGER), .
Note
If you specify the WSDL URL when creating the logical port of the consumer system, the WSDL automatically sets this option.
You know which signature certificate is to be used for the consumer system and know which keystore (PSE) it is stored in.
Note
If the consumer system uses CA certificates, you can import the CA certificate instead of the signature certificate.
In the Trust Manager of the consumer system, export the certificate for the consumer system to a file in the file system.
More information: Maintaining PSEs and Administering Certificates
Use the Trust Manager of the provider system to import the signature certificate into the WS-Security PSE WS Security Keys.
More information: Maintaining PSEs and Administering Certificates