A directed signature scheme allows a designated verifier to directly verify a signature issued to him, and a third party to check the signature validity with the help of the signer or the designated verifier as well. Directed signatures are applicable where the signed message is sensitive to the signature receiver. Due to its merits, directed signature schemes are suitable for applications such...

A directed signature scheme allows a designated verifier to directly verify a signature issued to him, and a third party to check the signature validity with the help of the signer or the designated verifier as well. Due to its merits, the directed signature scheme can be applied on some personally or commercially sensitive occasions. Up to now, there are several directed signature schemes havi...

Recently, Kyriakos et al. proposed a Partially Materialized Digest scheme (PMD). Their scheme uses separate indexes for the data and the verification information to realize the authenticity and completeness verification in outsourced database. In this paper, we analyze PMD and show the drawbacks in PMD such as the slow update, the collusion and forgery attacks, and no content access control etc...

Multi-Designated Verifier Signatures (MDVS) are privacy-oriented signatures that can only be verified by a set of users specified by the signer. We propose two new generic constructions of MDVS from variants of existing cryptographic schemes, which are ring signature from anonymous subset and multi-chameleon hash. We first devise a single add-on protocol which enables many existing identity-bas...

A lot of designated verifier signature (DVS) schemes have been proposed. However, all of them only provide the basic security requirement that only the designated verifier can check the validity of the signature. They are either not secure enough or lacking source hiding. Hence, in this article, we design a provably secure DVS scheme. It not only can attain the basic security requirement but al...

Hwang and Cheng proposed the first strong designated-verifier ring signature scheme providing one-out-of-all signer anonymity to hide the actual signer’s identity. Their scheme also provides signer admission to admit who the actual signer is. However, the computation and communication costs caused by the signer admission are heavy because their scheme needs all ring members’ Schnorr promises. T...

With the promotion of Remote Medical Treatment, sharing big telemedicine data becomes more and popular. Telemedicine based on wireless sensor networks collects blood pressure, pH value, pulse, other medical information from healthcare terminal. The is sent to hospital or server for processing. security protection patient data, such as confidentiality authenticity, has gradually become a critica...

Proxy signature schemes allow delegation of signing rights. The paper proposes the notion of Identity Based Strong Bi-Designated Verifier Proxy Signature (IDSBDVPS) schemes. In such schemes, only the two designated verifiers can verify that the proxy signer on behalf of the original signer signed the message but none of them is able to convince anyone else of this fact. The paper proposes nine ...

E-mail brings us lots of conveniences. Especially with help of PGP and S/MIME, it gives both confidentiality and message/origin authentication. However, in some cases for strong privacy, a message sender will not want to let others know even the fact that he sent a message to a recipient. Very recently, Harn and Ren proposed a fully deniable authentication scheme for E-mail where a sender can r...