# IoT and Blockchain Integration: Applications, Opportunities, and Challenges
## 6 Security Assurances and IoT Threat Model
### Definitions of Security Assurances  
#### 6.1.1 Confidentiality  
Confidentiality (or, privacy) [38] of data (or a message) in a storage device (such as hard disk, RAM) or a transmission channel (such as Ethernet cable, fiber optics, radio signal) ensures that the data [is not exposed/readable]/[remains secret] to illegitimate (unauthorized) parties but the authorized owner or a valid recipient of the message. For example, if any user, say, [PERSON], sends a message \(m\) targeted only to another user, say, [PERSON], on the other side through a public channel (medium), the confidentiality of the message ensures that any intermediate party, such as [PERSON], cannot read the message. For instance, as mandated by law [39], an individual may wish to keep his/her personal, professional, or academic matters secret; two people exchanging electronic mails or any digital or analog messages) wish to keep their communication secret to both of them. Data privacy [40] has been a crucial requirement in demand since the medieval period up until today's interconnected world. Several encryption algorithms such as Advanced Encryption Standards (AES), Data Encryption Standard (DES), Blowfish, Rivest-Shamir-Adleman (RSA), and Elliptic Curve Digital Signature Algorithm (ECDSA) are utilized to encrypt the data (message) to achieve data or communication confidentiality [41, 42]. Figure 4 depicts the simple flow of encryption and decryption schemes. Encryption is scrambling messages (data) so that illegitimate parties cannot read the message. Two major encryption schemes are (i) symmetric encryption scheme and (ii) asymmetric encryption scheme. Under symmetric encryption schemes, both encryption and decryption operations are performed by a shared secret key. Some of the algorithms that follow symmetric encryption schemes are Advanced Encryption Standards (AES), Data Encryption Standards (DES), and Blowfish, among others [41, 42]. Under asymmetric encryption schemes, two different keys are used for encryption and decryption. Each entity generates a pair of mathematically related public keys and private keys. The sender encrypts a message using the recipient's public key. The recipient with the private key for the public key used for  
\begin{table}
\begin{tabular}{l} \hline \hline
**Terminologies 1** \\ \hline “[Internet of Things, IoT] for Blockchain [Networks, technology]” \\ “Integration of [Internet of Things, IoT] and Blockchain [Networks, technology]” \\ “Challenges of [Internet of Things, IoT] and Blockchain [Networks, technology]” \\ “Issues in [Internet of Things, IoT] and Blockchain [Networks,technology] integration” \\ “Applications of Challenges of [Internet of Things, IoT] and Blockchain [Networks, technology]” \\ “Merging Challenges of [Internet of Things, IoT] and Blockchain [Networks, technology]” \\ “Combining Challenges of [Internet of Things, IoT] and Blockchain [Networks, technology]” \\ “Combination of Challenges of [Internet of Things, IoT] and Blockchain [Networks, technology]” \\ “[Using, Use of] Blockchain network for [health, hospitals, farm, farming, poultry, fishery]” \\ “[Using, Use of] Blockchain network for [agriculture, forestry, smart city, smart driving]” \\ “[Using, Use of] Blockchain network for [parking, war, smart grid, battle]” \\ \hline \hline \end{tabular}  
* The terms in a [] are used independently to produce all possible, unique search terms. Each search term can be used separately for a search or can be logically ORed with other search expressions.  
\end{table}
Table 3: Database search terminologies.  
encryption can decrypt the message using the private key. This scheme is also called public key cryptography. Examples of algorithms based on asymmetric encryption schemes are RSA, and ECDSA, among others [41; 42].