# From Bottom of Sea to Space: Quo Vadis IoT? So What About Security?
## 3 Security Challenges and Mechanisms
### IoT on the Ground
#### 3.2.1 Extensions with Applications in Medicine
To implement diffusion, a key from the Mandelbrot set can have XOR applied to the chaotic sequences and the image layer. The conditional shift algorithm should not use XOR on the key and original image. Using these improvements the authors agree that the initially proposed scheme can be implemented and used securely. Radio-frequency identification (RFID) is a resource constrained device that has had improvements in protection recently. Many access control systems use this type of device for high level security purposes. Such a device requires a lightweight cryptographic algorithm. The authors of [97] propose an algorithm called SLIM, which is a 32-bit block cipher based on the structure of the Feistel network. Since it is a block cipher, it uses the same key for encryption and decryption allowing for it to be more lightweight. SLIM has demonstrated a strong ability to prevent attacks on RFIDs. Another scheme to achieve security in IoHT is ciphertext-policy weighted attribute-based encryption (CP-WABE). But this system has several issues, including being non-scalable and requiring high computational cost, time, and memory. The authors of [98] propose some changes that, through theoretical and experimental analysis, have proven to be more efficient than CP-WABE. To resolve these issues, the authors use 0-1 encoding [99]. To make sure the scheme can run on a more inefficient system, offline/online encryption and outsourced decryption are used. Through experimental testing, the authors prove the scheme is more efficient than existing schemes. * Signcryption One of the greatest concerns for security in IoHT is the authenticity of a patients' health records sent over the Internet. Along with this is the anonymity of the sender and receiver of the data needing to be preserved. The current methods of signcryption that use certifiateless cryptography do not allow for security anonymity and the anonymity of the receiver at the same time. To solve this, the authors of [100] propose a form of signcryption based Hyperelliptic Curve Cryptosystem (HCC). The use of HCC in the proposed model creates lower computational costs to the system than in current systems that use cryptographic techniques such as RSA, elliptic curve cryptography (ECC), and bilinear pairing. Using the Random Oracle Model of testing, the authors were able to guarantee a high level of security when considering receiver anonymity, confidentiality, and unforgeability. * Data Provenance Provisions in Data Provenance are important if it is to be accepted by stakeholders. The proposed system by the authors of [101] suggests the use of a lightweight federated learning and differential privacy to protect the privacy and security of the data. The method would work in conjunction with blockchain smart contracts to manage the authentication of federated nodes, trust management, and edge training. To fully support the encryption of the dataset, federated nodes use additive encryption while the blockchain performs multiplicative encryption. The system was tested with deep learning applications and COVID-19 patient datasets. The authors claim that these tests provide strong potential for use in the IoHT. Although security is a critical design objective in the Internet of Health Things, it is not the only one. Researchers have studied other objectives such as performance [102], timeliness [103], and reliability [104] as well. Internet of Bodies In an Internet of Bodies, different kinds of worn, implanted, embedded or swallowed devices located in, on or around the human body are interconnected over a network. The Internet of Bodies has received a research focus in recent years. In one article [6] the authors deploy a programming framework for combining information from several source devices. This allows doctors to monitor and use multiple forms of data to better schedule computer-to-human interactions. In [105], the authors propose orthogonal and non-orthogonal capacitive body channel access schemes.