Abstract: Digital signature is a useful primitive to attain the integrity and authenticity in various wire or wireless communications. Proxy signature is one type of the digital signatures. It helps the proxy signer to sign messages on behalf of the original signer. It is very useful when the original signer (e.g. the president of a company) is not available to sign a specific document. If the original signer can not forge valid proxy signatures through impersonating the proxy signer, it will be robust in a virtual environment; thus the original signer can not shift any illegal action initiated by herself to the proxy signer. In this paper, we propose a new proxy signature scheme. The new scheme can prevent the original signer from impersonating the proxy signer to sign messages. The proposed scheme is based on the regular ElGamal signature. In addition, the fair privacy of the proxy signer is maintained. That means, the privacy of the proxy signer is preserved; and the privacy can be revealed when it is necessary.
Abstract: Deniable authentication is a new protocol which not only enables a receiver to identify the source of a received message but also prevents a third party from identifying the source of the message. The proposed protocol in this paper makes use of bilinear pairings over elliptic curves, as well as the Diffie-Hellman key exchange protocol. Besides the security properties shared with previous authentication protocols, the proposed protocol provides the same level of security with smaller public key sizes.
Abstract: Proxy signature helps the proxy signer to sign
messages on behalf of the original signer. It is very useful when
the original signer (e.g. the president of a company) is not
available to sign a specific document. If the original signer can
not forge valid proxy signatures through impersonating the proxy
signer, it will be robust in a virtual environment; thus the original
signer can not shift any illegal action initiated by herself to the
proxy signer. In this paper, we propose a new proxy signature
scheme. The new scheme can prevent the original signer from
impersonating the proxy signer to sign messages. The proposed
scheme is based on the regular ElGamal signature. In addition,
the fair privacy of the proxy signer is maintained. That means,
the privacy of the proxy signer is preserved; and the privacy can
be revealed when it is necessary.