International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Group Decryption

Bo Qin
Qianhong Wu
Willy Susilo
Yi Mu
Yumin Wang
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Abstract: Anonymity is one of the main concerns in group-oriented cryptography. However, most efforts, for instance, group signatures and ring signatures, are only made to provide anonymity on the sender's point of view. There is only a few work done to ensure anonymity in a cryptographic sense on the recipient's point of view n group-oriented communications. In this paper, we formalize the notion of group decryptions. It can be viewed as an analogousof group signatures in the context of public key encryptions. In this notion, a sender can encrypt a committed message intended to any member of a group, managed by a group manager, while the recipient of the ciphertext remains anonymous. The sender can convince a verifier about this fact without leaking the plaintext or the identity of the recipient. If required, the group manager can verifiably open the identity of the recipient. We propose an efficient group decryption scheme that is proven secure in the random oracle model. The overhead in both computation and communication is independent of the group size. A full ciphertex is about 0.2K bytes in a typical implementation and the scheme is practical to protect the recipient identity in privacy-sensitive group-oriented communications.
  title={Group Decryption},
  booktitle={IACR Eprint archive},
  note={ 13629 received 21 Jan 2007, last revised 26 Apr 2007},
  author={Bo Qin and Qianhong Wu and Willy Susilo and Yi Mu and Yumin Wang},