diff --git a/crypt_algo.hpp b/crypt_algo.hpp
index 763a8ba..6e22cf0 100644
--- a/crypt_algo.hpp
+++ b/crypt_algo.hpp
@@ -82,7 +82,11 @@
 
     protected:
 
-        /** @brief K2 is the key used for encrypting data */
+        /**
+         * @brief The Cipher Key is the first 128-bits of key “K2”, K2 is
+         * generated by processing a pre-defined constant keyed by Session
+         * Integrity Key (SIK) that was created during session activation.
+         */
         key k2;
 };