Science & Engineering Research Support soCiety (SERSC)
A convertible authenticated encryption scheme simultaneously provides the functions of integration, authentication, confidentiality and non-repudiation. A signer generates an authenticated cipher text signature on the chosen message. So that only a designated recipient can recover the message by using their secret key and verify the message by using the signer's public key. If there is a dispute, the recipient is able to convert the authenticated cipher text signature into an ordinary signature that can be verified by anyone. This paper separately points out that any adversary can forge a converted signature in Araki's scheme and Ma-Chen's scheme.