KeyScrub: A Reliable Key Backup and Recovery Method for Blockchain

On a blockchain platform, if a user has exposed or lost his/her private key, it may result in the loss of all the cryptocurrencies that he/she owns. It is critical to back up a user's private key and recover it at any time, without compromising the decentralized feature of the blockchain. The t-out-of-n secret sharing technique is typically used to support key backup and recovery in a blockchain, where a user's private key is divided into n partial keys, and the original private key can be restored only when at least t partial keys are available. This paper proposes a key scrubbing method, KeyScrub, to guarantee that at least t partial keys are available at any time in t-out-of-n secret sharing. The key scrubbing operation periodically (i.e., the scrubbing interval) checks how many partial keys are correctly maintained, and issues the recovery of partial keys without full recovery of the key. The reliability analysis of the proposed method shows a tradeoff relationship between the scrubbing interval and the values of t and n to meet the given reliability requirement for a key backup and recovery service.

Automated summary

On a blockchain platform, it is critical to back up and recover a user's private key in order to prevent loss of cryptocurrencies. This paper proposes KeyScrub, a key scrubbing method using t-out-of-n secret sharing technique to ensure the availability of at least t partial keys at any time. The reliability analysis shows the tradeoff relationship between the scrubbing interval and the values of t and n.