Both TREX and the application using TREX must be configured for using SNC. Since TREX is accessed by SAP Web Application Server (SAP Web AS) you have to prepare the SAP Web AS for SNC with the help of the SAP Cryptographic Library (SAPCRYPTOLIB) too. The SAP Web AS must possess a public and private key pair that is stored in its SNC PSE. It must also be able to identity its communication partners (in this case, TREX) using SNC.