Digital images captured from CCTV must have legally traceable time and accurate time and date stamps to be admissible as evidence in court proceedings. Many existing systems rely on internal PC clocks which drift over a period of time, becoming increasingly inaccurate. Other systems use time information available from the Internet, but this allows data to travel through a firewall, increasing the potential risk of hackers or viruses obtaining access into the network. Also, there are few or no guarantees that the information being provided is accurate or reliable.