Add support for DSA and ECDSA key types

Change-Id: Ibee8d172eeb36f1a2e2ce62f275aea55ada5bcbf
diff --git a/keystore-engine/keyhandle.cpp b/keystore-engine/keyhandle.cpp
index 786934b..1799735 100644
--- a/keystore-engine/keyhandle.cpp
+++ b/keystore-engine/keyhandle.cpp
@@ -58,3 +58,19 @@
     }
     return 1;
 }
+
+void *ex_data_dup(void *data) {
+    char* keyhandle = reinterpret_cast<char*>(data);
+    return strdup(keyhandle);
+}
+
+void ex_data_free(void *data) {
+    char* keyhandle = reinterpret_cast<char*>(data);
+    free(keyhandle);
+}
+
+void ex_data_clear_free(void *data) {
+    char* keyhandle = reinterpret_cast<char*>(data);
+    memset(data, '\0', strlen(keyhandle));
+    free(keyhandle);
+}