diff --git a/include/libeosio/WIF.hpp b/include/libeosio/WIF.hpp
index 9eca7fc..a402607 100644
--- a/include/libeosio/WIF.hpp
+++ b/include/libeosio/WIF.hpp
@@ -29,6 +29,14 @@
 
 namespace libeosio {
 
+/**
+ * Key prefixes. (strings that is not equal to these prefixes are treated as legacy format.)
+ */
+const std::string WIF_PUB_LEG = "EOS";
+const std::string WIF_PUB_K1  = "PUB_K1_";
+const std::string WIF_PVT_K1  = "PVT_K1_";
+
+
 /**
  * Encode an EC private key to WIF String.
  */