diff --git a/ndn-cpp/security/identity/identity-manager.hpp b/ndn-cpp/security/identity/identity-manager.hpp
index 4f4c8c2..2db82b1 100644
--- a/ndn-cpp/security/identity/identity-manager.hpp
+++ b/ndn-cpp/security/identity/identity-manager.hpp
@@ -13,6 +13,9 @@
 
 namespace ndn {
 
+/**
+ * An IdentityManager is the interface of operations related to identity, keys, and certificates.
+ */
 class IdentityManager {
 public:
   IdentityManager(const ptr_lib::shared_ptr<PrivateKeyStorage> &privateKeyStorage)
diff --git a/ndn-cpp/security/key-chain.hpp b/ndn-cpp/security/key-chain.hpp
index 708be9c..de85b98 100644
--- a/ndn-cpp/security/key-chain.hpp
+++ b/ndn-cpp/security/key-chain.hpp
@@ -23,6 +23,12 @@
  */
 typedef func_lib::function<void()> OnVerifyFailed;
 
+/**
+ * Keychain is main class of security library.
+ *
+ * The Keychain class provides a set of interfaces to the security library such as identity management, policy configuration 
+ * and packet signing and verification.
+ */
 class KeyChain {
 public:
   KeyChain(ptr_lib::shared_ptr<IdentityManager> identityManager)