# Precision Agriculture: A Remote Sensing Monitoring System Architecture +
## 7 Energy-Saving Techniques and Security Mechanisms
### Security Mechanisms  
Precision agriculture monitoring systems involve the exchange of sensitive information regarding the cultivation process, the state of crops and personal data of authorized staff. It is of great importance for such systems to be protected against cyber-attacks. An unauthorized entry of a malicious individual in the system may cause great damage to the cultivation process or even acquire the farmers personal information [47]. In the pursuit of safeguarding a smart farm monitoring system the confidentiality of data should be met. In addition, it is vital to ensure the reliability of the data and the ability to confirm that a message has not been tampered with, altered or changed while on the network. Also, the services of resources offered by the network, or by a single sensor node must be available whenever required and finally to be able to identify the origin of a message received. Basic security mechanisms are already deployed by the combined IoT technologies in every architectural level of the proposed smart monitoring system. However, there are more ways to increase the level of security in each layer separately. One popular way of providing physical layer security in WSN and IoT systems is cryptography. Physical layer security refers to the inner security capabilities of the Sensor layer regarding therandomness of wireless channels, the signal-to-noise ratio gaps or intended jamming. There are three kinds of cryptographic methods used in WSNs, the symmetric and asymmetric ones and hash functions. Hash functions are special mathematical functions which map a given input to a certain output with a fixed size. Well-known cryptographically secure hashes are the Secure Hash Algorithm-2 (SHA-2) and Advanced Encryption Standard (AES) algorithm. In symmetric cryptographic techniques, a single shared key is used between the two communicating nodes both for encryption and decryption. This key stays known only to the nodes of the network. On the other hand, in asymmetric cryptography, a private key can be used to decrypt and sign data. A public key is also used to encrypt and verify data. The private key needs to be kept confidential while the public key can be published freely. Asymmetric cryptographic techniques may use the RSA (Rivest-Shamir-Adleman) algorithm, the ECC (Elliptical Curve Cryptography) algorithm or the pairing technique. Popular frameworks of symmetric and asymmetric technique can be found in [48]. Regarding the Link layer of our proposed architecture security mechanisms focus against the interception, modification and fabrication of the exchanged data. Attack detection mechanisms can be applied, such as the misbehavior-aware threshold detection scheme for LLNs proposed in [49]. In addition, secure routing protocols may be used such as SAR(Secure aware routing protocol), which is based on on-demand protocol such as AODV or DSR and DPRAODV (Detection, Prevention and ReactiveAODV) [50]. Middleware security mechanisms deal with unauthorized modifications that occur due to transmission errors (accidental) and require the use of digital signatures. Digital signature schemes are cryptographic schemes that include key generation algorithms, signing algorithms and signature verifying algorithms. A digital signature is an authentication mechanism that enables the creator of the message to attach a code that acts as a signature. The Digital Signature Algorithm (DSA), developed by the National Institute of Standards and Technology, is one of many examples of a signing algorithm. Access control is an important building block for the overall security of a precision agriculture monitoring system. The IoT requires access control models that apply authorization policies across a multitude of smart sensors. In a smart farm monitoring platform, authentication is required to prevent authorized users from accessing resources in an unauthorized manner. For instance, a worker in the fields is a legitimate user but does not have the access rights as the main administrator farmer.