A convertible authenticated encryption scheme allows the signer to create a valid authenticated ciphertext such that only the specified receiver can simultaneously recover and verify the message. To protect the receiver’s benefit of a later dispute on repudiation, the receiver has the ability to convert the signature into an ordinary one that can be verified by anyone. However, the previous pro...

Designated verifier signature schemes are applied in situations such as electronic voting and electronic auctions. Signature recipients can ascertain the contents of the document, but cannot verify the identity of the signer to a third party. This study reviewed the protocols of past researches and analyzed whether these protocols would disclose signer identities under various types of attacks....

Multi signature is a signature scheme in which signers jointly generate a signature on a message. Threshold multisignature combines the traits of threshold signature and multisignature. In threshold multisignature, a group of users jointly generate a valid multisignature on a message and any one can verify the validity of the multisignature. However, in some applications the signed message is s...

In this paper, we propose a strong designated verifier proof signature scheme for an ad-hoc group and discuss its security properties. The proposed scheme provides a way that leaks authoritative secrets to only a designated person anonymously by one of the ad-hoc group members and no one knows that the secret is from a group member or the recipient, except the recipient. This group is called a ...

Designated verifier signature (DVS) is a cryptographic primitive that allows a signer to convince a verifier the validity of a statement in a way that the verifier is unable to transfer the conviction to a third party. In DVS, signatures are publicly verifiable. The validity of a signature ensures that it is from either the signer or the verifier. Strong DVS (SDVS) enhances the privacy of the s...

Strong designated verifier signatures make the message authenticated only to a designated person called the designated verifier while privacy of the signer’s identity is preserved. This primitive is useful in scenarios that authenticity, signer ambiguity and signer’s privacy are required simultaneously such as electronic voting and tendering. To have quantum-attack-resistant strong designated v...

Directed signature scheme allows only a designated verifier to check the validity of the signature issued to him; and at the time of trouble or if necessary, any third party can verify the signature with the help of the signer or the designated verifier as well. Due to its merits, directed signature scheme is widely used in situations where the receiver’s privacy should be protected. Threshold ...

In this paper we propose a new voting scheme that provides a receipt to each voters. The receipt is build in a way that prevents that the vote can be revealed to third entities other than a judge. The scheme is based on the concept of strong designated verifier signature scheme and threshold RSA signatures. The signing key size remains bounded by the size of a RSA modulus. The computational cos...