A measurement device, which communicates data to at least one system, and which has the capability of identifying measurement data returned by the system via the data communication as its own, and the capability to rule out manipulation of measurement values without use of a public or non-personal key. The measurement device includes at least an encryption and/or signature encoder that supplies information including a validity and reliability identifier for inspecting the integrity of the data, and compiles said information into a current data set and transfers it to at least said communication interface for transfer, and at least an encryption and/or signature decoder that inspects data sets returned via the communication interface using one or more keys in memory for integrity of data content and identification of the measurement device and, upon successful inspection of this data, supplies said data for further processing, evaluating or displaying.