A threshold encryption scheme without a dealer based on Chinese remainder theorem

Abstract

Secret sharing can improve the security and robustness of a system. So far, research on secret sharing without a dealer has been mainly focused on threshold signature, there are a few studies on threshold encryption. We put forward a new threshold encryption scheme without a dealer based on Chinese Remainder Theorem (CRT). To prevent the “authority deceive”, no dealer is needed and the secret shares are generated by the coordination of participants. A ciphertext can be deciphered indirectly by t or more partial decryption factors. In this process, the group private key can be used but can not be seen, so it is safe and reusable. Our scheme can also identify the mutual cheating among the participants by verifying the secret sharing shadows, which makes the scheme more secure and fair.