Analyzing Multisignature Scheme of Bitcoin Based on Threshold Cryptography Guidelines

Blockchain used cryptography to ensure that transactions are secure and consistent. However, conventional cryptographic techniques were based on a single secret key to protect transaction data. Blockchain transactions will be compromised if the secret key is leaked or stolen. Threshold cryptography provided an alternative solution to mitigate this issue. It secured the secret key by splitting it into multiple parts and distributing it among multiple parties. Many such parties had to collude to compromise the secret key of the threshold cryptography. This paper explored multisignature, a threshold signature scheme used in Bitcoin. This scheme defined subsets of signatories that can generate valid signatures and spend Bitcoin transactions. It decentralized spending authorization among multiple parties and protected the Bitcoin network from the single-point-of-failure event. The multisignature scheme was evaluated based on the proposed guidelines for threshold cryptography. The results highlighted the different properties of multisignature and inherent strengths and weaknesses. It also revealed its level of resistance to different categories of security attacks. Finally, the investigation results may guide future research works that use multisignature as their threshold signature scheme.