SCADA systems gather data from remote sensors and transfer that data to a central controller for analysis. As this data  is frequently of a confidential nature, securing that data is an important challenge. We can take two perspectives when examining Wireless Sensor Network (WSN) security - the security of the data in transit and the security of the network itself.

The data transferred from a WSN has to be protected from unauthorised viewing, unauthorised tampering or both. Cryptographic systems prevents viewing and tampering while Digital Signatures ensure data integrity. Digital signatures can ensure that data is from authorised senders and can also ensure that data arrives untampered. Quality of Service (QoS) metrics can also be met using digital signatures by ensuring that data isn't duplicated maliciously or otherwise. Encryption provides further protection by guarding against eavesdropping i.e. ensuring that the data cannot be viewed while it's in transit.

From the point of view of Network Security, device identities must be provable and data transfer from one mote to another or from a mote to a SCADA system must be authorised. Attacks should be logged and key management should be feasible.  This latter point is critical given the constrained nature of a typical sensor mote in terms of processing power and memory. For this reason non-traditional cryptographic techniques such as Elliptic Curve Cryptography (ECC) and Identity Based Encryption (IBE) should be considered. The former is an option that has been used by TinyOS and Java-based sensor motes.

SCADA-based WSNs typically consist of many motes with, as noted above, severe resource constraints. Given that SCADA systems have physical access to devices, the use of cryptographic protections might not be enough as attacks on these systems could be catastrophic in nature. It is argued  (See http://www.mdpi.com/1424-8220/9/11/9380/pdf) that a reputation system is required. Within this system only trusted data is transferred from sensor to server while the server provides the reputation to the sensor .

Given the critical nature of SCADA systems for many industries and utilities, the data that flows through the system needs to be secure. The introduction of WSNs into a SCADA system can damage that security unless appropriate security provisions are made be they digital signing, cryptography or a reputation-based system.

The key value of Wireless Sensor Networks is the monitoring of physical and industrial environments. This data needs to be transformed into meaningful information that can be used by business decision makers using the Vertoda Framework. Furthermore, much of this data can also play a role in SCADA (Supervisory Control And Data Acquisition)  systems. SCADA systems are fundamental to operations in the pharmaceutical, oil & gas, food processing and other process driven industries and the data provided by WSNs could certainly enrich the information provided by such systems.

One option for connecting WSNs to SCADA systems is to use Vertoda Middleware. The Vertoda Framework will capture the data from the WSNs and distribute pre-sorted and translated information to the SCADA system. This would be an ideal mechanism for fusing the data capturing power of WSNs with the well established SCADA systems used in certain industries. To date, WSNs have not met market expectations for certain sectors. The answer to that issue may be to make their data more easily available to the existing systems used by an industry sector.

The other option for connecting WSNs to SCADA is to connect the SCADA system directly to the WSNs. However, this is more difficult than initally appears as custom software will need to be created for the system. This could be achieved using a bespoke Vertoda Data Capture module.

Within a SCADA model, data is captured by sensors and communicated to a central controller which analyses the data and takes appropriate actions. It is a well established standard and has the flexibility to accomodate wireless networks. However, as noted, up to now WSNs have not been deployed extensively within industries that typically use SCADA systems. It can be argued that the key reason for this is that industries such as pharmaceuticals are regulatory driven and WSNs were too much of risk for plant and process management. The key requirement for the use of WSNs is that they be reliable. WSNs in industries such as oil & gas and pharmaceuticals need to withstand harsh, often outdoor environments. Up to recently, WSNs were still technology that was primarily suited to benign indoor environments but the motes have become much more robust.

WSNs must also easily interoperate with other devices and systems. The data produced by WSNs does not exist in isolation - it is required by other devices and systems to make decisions and take actions. Vertoda solves this problem by making WSN information available to any other system within the organisation. WSNs must facilitate route configuration i.e. if one mote is damaged it must not be a bottleneck or point of failure for the rest of the network. The other area of concern for  the process industry is the perceived insecurity of WSNs - a topic we will return to in a future blog.