Threshold Proxy Re-encryption and Its Application in Blockchain

Since the proxy re-encryption has the limitation of distributed applications and the security risk of collusion attacks in semi-trusted distributed environments (e.g. cloud computing), the novel definition of threshold proxy re-encryption is proposed based on secret sharing and proxy re-encryption. According to the definition, the threshold proxy re-encryption scheme can be flexibly created with the standard cryptographic prototype. An efficient, secure, and implementable unidirectional threshold proxy re-encryption scheme is constructed by the combination of Shamir’s secret sharing, and is proved secure by using the intractability of discrete logarithms. This paper presents a consortium blockchain access permission scheme, which is built on the threshold proxy re-encryption scheme. When a new node joins a consortium blockchain, an access permission is achieved by the agreement on other existing nodes, instead of a centralized CA.