IKE: Threshold Key Escrow Service with Intermediary Encryption

Blockchain has gained significant attention for its potential to revolutionize various fields. The security of the blockchain system heavily relies on private key management, and traditional key management schemes pose a higher risk of key compromise or loss. A general key management solution with security supervision is needed to overcome the problems in the traditional key management scenario and ensure the long-term development of the blockchain system. Drawing upon the aforementioned principles, this paper proposes a threshold key escrow scheme with intermediaries that affords secure, generic and convenient distributed key escrow services. The scheme utilizes Paillier encryption and intermediary encryption to provide two layers of encryption protection for the escrow key. Moreover, we consider the recovery needs of committee member changes and key share losses in practical scenarios and propose secure methods to obtain new shares. Finally, we prove the correctness and semantic security of the scheme; and through theoretical and the practicability and efficiency of the scheme in practical applications are verified through theoretical and experimental analysis.