IACR News item: 04 March 2021
Amril Syalim, Takashi Nishide, Kouichi Sakurai
ePrint Report
A proxy re-encryption scheme can be executed by a semi-trusted proxy, so that we can transform a ciphertext encrypted with a key to another ciphertext encrypted with different key without allowing the proxy to access the plaintext. A method to implement a secure proxy re-encryption is by first converting the plaintext to an intermediate form by using an all or nothing transform (AONT). In this paper, we describe an improved proxy re-encryption scheme for symmetric cipher by advocating the usage of a variant of the AONT function in the proxy re-encryption scheme. We show that the scheme secure under Chosen Plaintext Attack (CPA) for all possible types of attackers.
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