# Assessing Cyber Challenges of Maritime Navigation
## 4 Discussion
National defense forces are already in the hunt for alternate position, navigating, and timing (PNT) systems (to GPS) within two years. Even though military commanders would prefer equipment that does not need to rely on GPS because their current systems are increasingly being jammed or spoofed, the costly GPS III program is going to be developed in the USA. It will be designed to include improved anti-jam features, including the higher-fidelity M-Code signal for military users only [81]. In the meantime, the US Air Force is looking for solutions that could provide alternative signal sources that might even be from a non-US GNSS system. Lockheed U-2 high altitude reconnaissance jet pilots wear GPS-enabled smartwatches (Garmin D2 Charlie) for navigation backup in case their GNSS signal becomes unavailable [80]. Watches are capable of receiving multiple navigation signals including GPS, GLONASS, and BeiDou. Indeed, the combination of multiple GNSS systems in a smart receiver makes spoofing much more difficult, and now that Galileo is available worldwide, it is already used in over a billion smartphones [138]. The questions we might be asking here are  
* Is it not a bit unusual that a superpower state does not have its alternative navigation system for their own defense forces in order not to rely on the signal sources of their rivals? * Would it not be wise to develop and put into practice GPS-enabled smartwatches for mariners in case their GPS signal onboard becomes unavailable? * Is there any viable non-GNSS alternative or backup system for vulnerable GPS navigation? At this stage, we might find an answer only to the third question. IMO recognizes the need for multiple PNT systems onboard maritime vessels. However, there has been no widely available substitute system for GPS navigation, although, now Galileo is becoming a viable alternative. IMO has developed the e-Navigation concept to increase maritime safety and security via means of electronic navigation, based on (at least) two different independent sources of the PNT system to make it robust and fail-safe. The most viable terrestrial system providing PNT services that meets IMO's requirements an enhancement of LOng-RAnge Navigation (LORAN)--eLoran. Not precisely as accurate as GPS, it can provide sub-5 m (in the Netherlands) to sub-10 m (in the United Kingdom) horizontal positioning accuracy. It meets the availability, integrity, and continuity performance requirements for maritime harbor entrance and approach manoeuvres, aviation non-precision instrument approaches, land-mobile vehicle navigation, and location-based services [83; 84; 85]. Galileo offers the Public Regulated Service (PRS) which is encrypted to protect against spoofing [139]. However, that is only available for use by authorities. However, in the near future, it will offer (free) Open Service Navigation Message Authentication (OS NMA) that will provide a low level of protection against spoofing, and a (paid) Commercial Authentication Service (CAS) that is encrypted like PRS--but for commercial use--while also providing higher accuracy [140]. [PERSON] et al. [37; 38; 39] presented an impressive laser-based aid system for berthing and docking that is providing accuracy within 2 cm even when the GNSS satellite signal is obstructed by Ship to Shore (STS) cranes, or redirected. This system could be one of the core subsystems required for collision avoidance [141; 142] of autonomous surface vessels, which still require solutions for a variety of technical problems [113]. The answer to the third question could eventually come about by a public-private partnership. [PERSON] [143] predicts that companies such as [PERSON]'s SpaceX and Amazon's Project Kuiper, maintaining networks with hundreds of low-Earth-orbit satellites, will eventually become a vital component of the GNSS ecosystem. The new GNSS will pick up the slack in the event of malfunctions or attacks.