This article is to propose a consensus algorithm, called Proof of Chance (PoCh), which is designed for the industrial Internet of Things (IIoT). The PoCh protocol is designed to be scalable and extensible, with a controllable conformance delay and low hardware and computation requirements. To reach a consensus, PoCh uses chance rather than computing power: “if condition $_{1}$ , I am a candidate; if condition $_{2}$ , I am the miner.” During every consensus iteration, the condition $_{1}$ is updated, and a single miner is chosen using condition $_{2}$ . Those conditions are randomized without the node generating any value and without assigning any weight to such value. The fault tolerance of PoCh is $5f/3 + 1$ , meaning that PoCh can successfully achieve consensus as long as more than 40% of nodes are functioning properly, compared to 50% in the Proof of Stake (PoS) protocol.

Digital signature schemes are practical mechanisms for achieving message integrity, authenticity, and non-repudiation. Several asymmetric encryption techniques have been proposed in the literature, each with its proper limitations. RSA and El Gamal prove their robustness, but are unsuitable in several domains due to their computational complexity. Other asymmetric encryption schemes have been proposed to provide a cloud homomorphic encryption service, where the researchers focused only on how to ensure the homomorphic property. This paper proposes a new digital signature scheme dedicated to a family of encryption techniques. The proposal consists of two parts: the first focused on the secret key, and the second focused on the public key. Signature validity checking was performed by multiplying these two parts to reform again the sender’s public key, then comparing the result with the decrypted message. The validation of the decrypted message guarantees data integrity, where the signer public key is used to ensure authenticity. The proposed scheme takes a shorter execution time for the entire signature operation, including signing and verification, compared to other modern techniques. The analysis showed its robustness against private key recovery and forgery attacks. The implementation results of the proposed scheme showed promising performance in terms of complexity and robustness. The results confirmed that the proposed scheme is efficient and effective for signature generation and verification.

In today’s hyperconnected world, the Internet of Things and Cloud Computing complement each other in several areas. Cloud Computing provides IoT systems with an efficient and flexible environment that supports application requirements such as real-time control/monitoring, scalability, fault tolerance, and numerous security services. Hardware and software limitations of IoT devices can be mitigated using the massive on-demand cloud resources. However, IoT cloud-based solutions pose some security and privacy concerns, specifically when an untrusted cloud is used. This calls for strong encryption schemes that allow operations on data in an encrypted format without compromising the encryption. This paper presents an asymmetric multi-key and partially homomorphic encryption scheme. The scheme provides the addition operation by encrypting each decimal digit of the given integer number separately using a special key. In addition, data integrity processes are performed when an untrusted third party performs homomorphic operations on encrypted data. The proposed work considers the most widely known issues like the encrypted data size, slow operations at the hardware level, and high computing costs at the provider level. The size of generated ciphertext is almost equal to the size of the plaintext, and order-preserving is ensured using an asymmetrical encryption version.

Several trusted tasks use consensus algorithms to solve agreement challenges. Usually, consensus agreements are used to ensure data integrity and reliability in untrusted environments. In many distributed networking fields, the Proof of Work (PoW) consensus algorithm is commonly used. However, the standard PoW mechanism has two main limitations, where the first is the high power consumption and the second is the 51% attack vulnerability. In this paper, we look to improve the PoW consensus protocol by introducing several proof rounds. Any given consensus node should resolve the game of the current round $Roun{d}_i$ before participating in the next round $Roun{d}_{i+1}$. Any node that resolves the game of $Roun{d}_i$ can only pass to the next round if a predetermined number of solutions has been found by other nodes. The obtained evaluation results of this technique show significant improvements in terms of energy consumption and robustness against the 51% and Sybil attacks. By fixing the number of processes, we obtained an energy gain rate of 15.63% with five rounds and a gain rate of 19.91% with ten rounds.

The transformative potential of blockchain technology has resulted in its widespread adoption, bringing about numerous advantages such as enhanced data integrity, transparency, and decentralization. Blockchain has effectively proven its ability to establish trustworthy systems across a multitude of applications. As the number of transactions recorded into a blockchain grows, the blockchain’s size expands significantly posing challenges to the network, particularly in terms of storage capacity and processing power. To address this problem, we present a cryptosystem based on RSA to provide aggregate signatures in blockchains. The aggregate signature replaces all transaction signatures of a block. In this scheme, all participating blockchain nodes use the same modulus N , each with its own private and public key pair generated from N . Regardless of the number of transactions, nodes, and signers, the aggregate signature size is always O(k) , where k is a security parameter. The miner that constructs a candidate block computes the aggregate signature σ, replaces all transaction signatures by σ, and transmits the block with only one aggregate signature. The proposed scheme incorporates a flexible and accountable subgroup aggregate signature mechanism, allowing any subset t of n total elements to sign data, where t is the required number of signers. To verify that a set of elements signed the block, the verifier requires the aggregate signature, the aggregate public key, and the data hash. This approach requires minimal interaction between the signers, which results in reduced network traffic. Regardless of the network size, there are always t + n exchanged messages. Experimental analysis shows the proposed aggregate signature scheme’s effectiveness in increasing security robustness and reducing block size and overall network traffic.