An Enhanced Threshold RSA-Based Aggregate Signature Scheme to Reduce Blockchain Size

Chait, Khaled ORCID: https://orcid.org/0000-0001-8744-3901, Laouid, Abdelkader ORCID: https://orcid.org/0000-0002-8175-8467, Kara, Mostefa ORCID: https://orcid.org/0000-0002-5736-8039, Hammoudeh, Mohammad ORCID: https://orcid.org/0000-0002-9735-2365, Aldabbas, Omar and Al-Essa, Abdullah T (2023) An Enhanced Threshold RSA-Based Aggregate Signature Scheme to Reduce Blockchain Size. IEEE Access, 11. pp. 110490-110501. ISSN 2169-3536

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Abstract

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 $\sigma $ , replaces all transaction signatures by $\sigma $ , 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.