You want to confirm the supported cipher list for Secure ICAP negotiation.
Release: Data Loss Prevention 15.7
Component: Network Prevent for Web
The supported cipher list is the same as those provided by the Java Runtime Environment (JRE). For reference, check the table "Default Enabled Cipher Suites" and refer to column "JDK8" on this page: Java Cryptography Architecture Oracle Providers Documentation for JDK 8. Note the actual cipher used is the strongest common cipher between both endpoints.