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A publicly verifiable PCAE scheme for confidential applications with proxy delegation

With the diversity of business transactions, new application requirements will emerge. Many confidential transactions, such as online auctions and bank savings withdrawals, sometimes might be conducted by an authorized proxy. In this paper, we propose a bilinear pairing‐based proxy convertible authenticated encryption scheme. The proposed scheme allows the delegated proxy signer to generate an authenticated ciphertext in behalf of the original signer while only the designated recipient is able to decrypt the ciphertext and verify the proxy signature. To benefit the encryption of a large message, we further present another variant with message linkages. Both schemes are publicly verifiable, that is, the designated recipient can convert the ciphertext into an ordinary proxy signature for public verification. In addition, the security requirement of confidentiality against indistinguishability under adaptive chosen‐ciphertext attacks and that of unforgeability against existential forgery under adaptive chosen‐message attacks are proved in random oracle models. Copyright © 2011 John Wiley & Sons, Ltd.