Trust your wallet: A new online wallet architecture for Bitcoin

Online wallet has become an important method to manage Bitcoin. In a Bitcoin transaction, online wallet manages the private key automatically, and stores the encrypted private key in remote to ensure the accessibility of Bitcoin anywhere. In the traditional online wallet, the private key is stored centrally in a storage unit. However, if the storage unit is collapsed or hacked, users will suffer the risk of losing their Bitcoins. Motivated by this, in this paper, we propose a new online wallet architecture: HA-eWallet. In HA-eWallet, the transaction of Bitcoin is signed by multiple private keys rather than one, and private keys are stored separately in different places. In addition, we introduce a second service unit to construct the Active-Active architecture to rotate the capability and workload. Besides, we adopt a disaster recovery strategy in our proposed architecture in case of any disaster. According to the running states of each service unit, HA-eWallet have three operation models, and can be switched smoothly. Theoretical analyses and experiments show that: HA-eWallet can achieve higher availability compared with the traditional online wallet architecture, and users will not suffer a loss as long as the number of lost private keys are less than 50% of the users' total number of private keys.