# Clone Node Detection Attacks and Mitigation Mechanisms in Static Wireless Sensor Networks
## 4 Mitigation of the Replication Attacks in Static Wireless Sensor Network
### Authentication Methods in Wireless Sensor Network  
As new threats and attack models are discovered and launched in wireless sensor networks (WSNs), various kinds of authentication techniques have been proposed in WSNs security (See [43] for the various authentication protocols in WSNs). Regarding the information security topic, it is extremely important to force the attacker make additional difficult actions in order to gain access to our electronic and/or digital information after he had physical access to our devices. Therefore, good security mechanisms should be employed on that particular device or network to restrict access to unauthorized entities. Some of these powerful techniques can be Encryption, Encoding, Hashing, Authentication, and two-step verification, etc. However, these methods, at some points, can slow down the performance of a system. As a result, applying them to a system where the availability feature of the triad is the priority, such as ICS, the experts in charge should think twice about how severe the consequences will be.  
Broadcast messages: ordinarily have one sender and multiple receivers. Broadcast messages are directly obtained from authentic, genuine sources and cannot be altered during transmission. The fundamental elements of a broadcast authentication process are:  
(a) Verifying the origin of the messages to check if the source is what it says it is.  
(b) After the step above is performed, and the source is found as legitimate, it is time for the confirmation of the message integrity.  
This authentication reduces forgery, impersonation, and replay attacks.  
Cryptographic Methods: There exist two (2) authentication techniques when it comes to cryptography, _symmetric_ and _asymmetric_ methods. In the first method, there is a single cryptographic shared-key for both parties (sender and receiver) to apply for authentication and verification before they start a communication. Some examples of symmetric encryption: AES (advanced encryption standard), Blowfish, DES (data encryption standard), RC4 (Rivest Cipher 4), RC5 (Rivest Cipher 5), RC6 (Rivest Cipher 6). (For more information, please see [44, 45]).  
In the second method, a cryptographic public key is used. This method uses two (2) keys to encrypt/decrypt a text message, which can be plaintext or cyphertext. Usually, secret keys (commonly called private keys) are exchanged locally or over the Internet. However, it ensures that pernicious persons do not misuse the keys. When a message is encrypted using a public key, then anyone with the respective private key can decrypt that message. Vice-versa, a message encrypted with a private key can be decrypted with the appropriate public key. However, usually, the public keys are made to be public, and the private key is mostly used to decrypt the cyphertext. Some examples of asymmetric encryption are RSA, Diffie-Hellman, DSA, ECC, El Gamal. (For more information, please see [45, 46]).  
Apart from the authentication techniques, another great factor that can undoubtedly be useful for the detection and mitigation of the clone node attacks is the subject of _semantic technologies_ and, hence, _ontology_. This approach can help data aggregation of the sensor network and can well manage how the queries (such as node messages) are roaming in the wireless sensor networks. (For more information about wireless sensor network, please see [47, 48, 49]). Additionally, it can allow a good establishment of the security layer, which will enhance the security of the WSNs. Thus far, several ontology approaches have been introduced for the semantic presentation of sensor networks concepts (for information, please see Section 6). In the following chapter, we propose an ontology scheme that will serve as good support for the static WSNs detection and mitigation techniques for the clone node attacks (replication attacks).