Improvement on a Threshold Authenticated Encryption Scheme

Abstract

The authenticated encryption scheme allows one signer to generate an authenticated cipher-text so that no one except the designated verifier can recover the message and verify the message. In a (t, n) threshold authenticated encryption scheme, any t or more signers can generate an authenticated encryption for a message and send it to the designated verifier. Compared with the conventional encryption-then-signature schemes, threshold authenticated encryption schemes can meet more security requirements, including robustness, confidentiality, unforgeability, integrity, authenticity and non-repudiation. Based on Tseng and Jan’s authenticated encryption scheme and elliptic curve cryptosystem, Chung et al. [2] recently proposed an efficient (t, n) threshold authenticated encryption scheme which can reduce the load of the signers by applying a division-of-labor signature technique. However, the paper demonstrates that there exists a design defect, the threshold authentication signature scheme cannot resist against insider attack and the scheme is not robust. Then, an improved authenticated encryption scheme based on elliptic curve cryptosystem is proposed. The novel authenticated encryption scheme removes the above-mentioned weaknesses.