## CryptoDB

### Chunxiang Gu

#### Publications

Year
Venue
Title
2008
EPRINT
A ring signature allows a user from a set of possible signers to convince the verifier that the author of the signature belongs to the set but identity of the author is not disclosed. It protects the anonymity of a signer since the verifier knows only that the signature comes from a member of a ring, but doesn't know exactly who the signer is. This paper proposes a new ID-based ring signature scheme based on the bilinear pairings. The new scheme provides signatures with constant-size without counting the list of identities to be included in the ring. When using elliptic curve groups of order 160 bit prime, our ring signature size is only about 61 bytes. There is no pairing operation involved in the ring sign procedure, and there are only three paring operations involved in the verification procedure. So our scheme is more efficient compared to schemes previously proposed. The new scheme can be proved secure with the hardness assumption of the k-Bilinear Diffie-Hellman Inverse problem, in the random oracle model.
2006
EPRINT
In this paper, we propose an efficient ID-based signature scheme based on pairing. The number of paring operation involved in the verification procedure is one. Our scheme is proved secure against existential forgery on adaptively chosen message and ID attack under the hardness assumption of computational Diffie-Hellman problem, in the random oracle model.
2006
EPRINT
Public key encryption with keyword search (PEKS) enables user Alice to send a secret key $T_W$ to a server that will enable the server to locate all encrypted messages containing the keyword $W$, but learn nothing else. In this paper, we propose a new PKES scheme based on pairings. There is no pairing operation involved in the encryption procedure. Then, we provide further discussion on removing secure channel from PKES, and present an efficient secure channel free PKES scheme. Our two new schemes can be proved secure in the random oracle model, under the appropriate computational assumptions.
2006
EPRINT
This paper proposes a new ID-based proxy signature scheme based on the bilinear pairings. The number of paring operation involved in the verification procedure of our scheme is only one, so our scheme is more efficient comparatively. The new scheme can be proved secure with the hardness assumption of the k-Bilinear Diffie-Hellman Inverse problem, in the random oracle model.
2006
EPRINT
Signature schemes with message recovery have been wildly investigated a decade ago in the literature, but the first ID-based signature with message recovery goes out into the world until 2005. In this paper, we first point out and revise one little but important problem which occurs in the previous ID-based signature with message recovery scheme. Then, by completely different setting, we propose a new ID-based signature scheme with message recovery. Our scheme is much more efficient than the previous scheme. In our scheme (as well as other signature schemes with message recovery), the message itself is not required to be transmitted together with the signature, it turns out to have the least data size of communication cost comparing with generic (not short) signature schemes. Although the communication overhead is still larger than Boneh et al. 's short signature (which is not ID-based), the computational cost of our scheme is more efficient than Boneh et al. 's scheme in the verification phase. We will also prove that the proposed scheme is provably secure in the random oracle model under CDH Assumption.

#### Coauthors

Takeshi Okamoto (1)
Eiji Okamoto (1)
Xiaoyu Pan (1)
Raylin Tso (1)
Yajuan Zhang (1)
Yuefei Zhu (4)