make generate_key more efficient
make generate_key more efficient

OptimusLime/lua-websockets,OptimusLime/lua-websockets,lipp/lua-websockets,KSDaemon/lua-websockets,lipp/lua-websockets,lipp/lua-websockets,KSDaemon/lua-websockets,enginix/lua-websockets,enginix/lua-websockets,enginix/lua-websockets,OptimusLime/lua-websockets,KSDaemon/lua-websockets