# Security and Independence of Process Safety and Control Systems in the Petroleum Industry
## 5 Measures to Resist Cyberattacks
### Encryption  
An important vulnerability in today's OT systems is that they often contain older equipment that does not have built-in support for cryptography. This means that high data integrity depends on good shell protection. Digital signatures or message authentication codes (MAC), which provide the ability to verify that data is authentic and has not been altered, are not usually used in OT systems. DNV-RP-G108 [10] contains the following recommendation:  
* Symmetric encryption: AES 128 or better.
* Asymmetric encryption: RSA 2048 or better.
* Hash: SHA-224 or better.  
There has been a previously widespread misconception that encrypting a communication channel (for example, in the form of a Virtual Private Network) makes it impossible to manipulate the data transmitted without it being detected by the recipient. In recent years, however, the IT industry has had to accept that such guarantees can only be given if one of the more closely defined protocols for authenticated encryption is used, such as AES-GCM [29] or AES-CCM [30].  
If quantum computers become available in the short term, this will lead to dramatic changes in which algorithms and key lengths provide sufficient levels of security [31]. If this is to be taken into account, this may, among other things, have the following consequences:  
* Today's public-key algorithms that rely on discrete log or factorization of large numbers (Diffie-Hellman, RSA, and ECC are the most common examples) need to be replaced with quantum-safe options.
* The key length of symmetric encryption algorithms (AES) must be doubled--256 bits or more.
* The length of hashes must be doubled (SHA3-384 or SHA3-512).  
As of today, there is no consensus on which public-key algorithm to choose; however, various alternatives are being developed. Authenticated encryption does not appear to be an issue that receives a great deal of attention in the petroleum industry; neither is quantum-proof encryption.  
Depending on the choice of profile in IEC 62443, encryption requirements may apply, and the OPC UA may also include encryption. There are also drawbacks to using encrypted messages within OT due to the fact that signature-based IDs (Snort, Suricata, Bro...) will not be able to detect intrusion attempts. Network monitoring will then also become more difficult. For individual applications, it is possible to consider proxy solutions that decrypt the traffic entering/exiting specific zones.  
Encryption between devices in OT has not been implemented on Norwegian facilities, partly because the equipment used today rarely supports the encryption of traffic, and partly because encryption/decryption requires resources and may come at the expense of response time and the possibilities for exchanging information between the individual systems, and the operator interface may also be slower. Shell protection in the form of zones and conduits according to IEC 62443 may, in the short term, represent a better solution for OT systems.  
There are SIL 4 certified hardwired safety systems in accordance with IEC 61508, where logic cannot be influenced via ICT systems. The logic is not vulnerable to ICT threats, and information and status can be extracted, for example, with OPC (but the OPC part has not yet been certified according to current IEC 62443 standards). This means that logic does not need protection against ICT threats, while the information on OPC has the same challenge as other software-based infrastructure.