Custodian-Hiding Verifiable Encryption.
Joseph K. Liu, Victor K. Wei, Duncan S. Wong · 2004
In a verifiable encryption, an asymmetrically encrypted ciphertext can be publicly verified to be decipherable by a designated receiver while maintaining the semantic security of the message [2, 6, 9]. In this paper, we introduce Custodian-Hiding Verifiable Encryption, where it can be publicly verified that there exists at least one custodian (user), out of a designated group of n custodians (users), who can decrypt the message, while the semantic security of the message and the anonymity of the actual decryptor are maintained. Our scheme is proven secure in the random oracle model. We also introduce two extensions to decryption by a subset of more than one user.