Got it working… prehaps its not best solution but its working for me.
I using the sha256.h and sha256.cpp file from zedwood function. found here
http://www.zedwood.com/article/cpp-sha256-function
Jah need to insert the #define _CRT_SECURE_NO_WARNINGS in the sha256.cpp
Because the function expects std.string and not fstring … jah need to convert them like this
FString hash_user_name = *FString(sha256(TCHAR_TO_UTF8(*User_Name)).c_str());
Then jah can get the code working and jah got a nice sha256 hash signature.