Wireless sensor network (wireless sensor network) is a network that consists of connecting consisting of computing components, data processing and communication, which are used to exchange, collect information and send data using sensors and battery power obtained to the terminal for further processing . The popularity of using WSN is because of its ability to be implemented in various fields at a low cost.
WSN has unique characteristics that distinguish it from ordinary networks. Computational capability and WSN computation are more limited with limited memory capacity and power as well. The use of WSN is usually installed in an environment that is physically accessible thereby increasing the potential for physical attacks. Although WSN utilizes wireless network techniques, security services for wireless networks cannot be applied directly to WSN because of the unique features and application requirements.
This certainly becomes an issue of security at WSN, but the rapid development of WSN requires further research as many new security issues and techniques are developed. The expected operating characteristics and application of wireless sensor networks have also opened new possibilities for security threats. Data can be stolen or altered during transmission or valid malicious sensors can inject false information into the network. In addition, a group of Denial of Service (DoS) attacks severely damage resource-limited wireless sensor systems, as well as demanding security measures.
- WSN Security Aspects
A WSN is a special form of ad-hoc network that has several differences and limitations on several sides. Regarding security, there are several considerations that need attention:
1) Limited resources, including memory and power. With this limitation the code size of the network security algorithm must be limited. Whereas the more complicated the algorithm level the code will use the greater energy.
2) Lack of effective communication, which includes ineffective data transfer, conflicts between packages. The use of protocols and the effects of channel errors can cause packet defects. Network congestion, multi-hop routing and the presence of processor nodes will spur greater latency on the network which makes synchronization between networks difficult to achieve.
3) Unattended network operations so that WSNs are placed in remote areas that are easy to physically exploit and remote sensor control makes physical interference detection more difficult.
In WSN, security requirements can be classified as follows:
- Confidentiality, where information cannot be accessed by unauthorized parties.
- Integrity, which ensures information received is not altered from the original.
- Authentication, to ensure the reliability of origin of information.
- Availability, which guarantees users to be able to access WSN services whenever needed despite an attack.
- Novelty of data and keys, where the data generated and keys used are the latest.
- Self-regulation where the sensor node is free and flexible to independently react to problem situations.
- Authority, where only authorized entities can access network services and resources.
- Time synchronization for most applications in WSN.
- Secure localization, especially for sensors that require location information accurately and automatically.
- Forward / backward secrecy where a sensor is not permitted to know information after the sensor has left the network and the newly joined sensor cannot know the message sent earlier.
There are several types of security attacks against WSN. Some types such as man-in-the-middle attack on sensor network communications, attacks can be divided into 2 namely passive and active attacks. In passive attacks, unauthorized parties can access data packets without making changes to network communications for example by traffic analysis, while active attacks disrupt network functionality by launching Denial of Service (DoS) attacks such as jamming and Distributed Denial of Service (DDoS) which attack on the entire WSN network.
This activity is classified as a security threat to the wireless sensor network as internal or external, depending on the possible origin of the attack. External attacks come from outside the network, while internal attacks will be executed by legitimate users which will be carried out in an unintentional manner. The activity also defines that the attack may be passive, without network modification, or active, where the data flow is changed or created.
The goal, attacks can be divided into 3 types, namely attacks on confidentiality and authentication, attacks on the availability of services and attacks on data integrity. Standard cryptographic techniques can overcome such as tapping, packet replay, and spoofing. Attacks on service availability are often also referred to as denial of service (DoS) which is an event that weakens or tries to reduce the capacity of the network so that the network does not work according to the function that it should. Whereas in an attack on data integrity, an attacker aims to make the network receive incorrect data.
- Cryptography, Cryptography is the basic encryption method used in applying security. The selection of cryptography plays an important role in WSN security. In general there are two approaches, namely symmetric key cryptography and asymmetric (public key). Symmetric key cryptography uses the same key for the encryption and decryption process while the public (asymmetric) key method uses different keys for encryption and decryption. Examples of symmetric keys are RC4, RC5, RC6, IDEA, SHA-1, MD5 Rijndael, BSPN. Examples of asymmetric keys / public keys are RSA, ECC.
- Key Management, Key management is used to determine the keys used between networks in a safe and reliable way. The scheme used must be able to support the addition and reduction of networks dynamically and because of limited resources, this key management protocol must be lightweight. Based on network structure, there are 2 types of key management, namely centralized and distributed keys. In a centralized key scheme, there is only one person who has the role of regulating the generation and distribution of keys called the Key Distribution Center (KDC). Although this scheme can reduce the need for storage at sensor nodes, it has an impact on high communication costs and failure vulnerability concentrated at one point. Whereas in distributed protocols, several different controllers are used to manage keys, which allows for vulnerability to failure.