Ambiguous Multi-Symmetric Cryptography

In this paper, we propose a new method called Ambiguous Multi-Symmetric Cryptography (AMSC) that conceals multiple plain-texts in a cipher-text using the same number of keys. The goal of this method is to overcome the problem of symmetric cryptography failure when the shared key is exposed. The proposed method AMSC is a cryptographic primitive that preserves plausible deniability after a cryptographic key is discovered. We evaluate AMSC in terms of security and complexity. The security analysis shows that our scheme withstands all security attack models with different knowledge of the adversary. In terms of time complexity, AMSC produces the cipher-text in polynomial time with respect to the number and size of the plaintexts and keys. AMSC has two main applications: a) It sends multiple messages for multiple receivers through one cipher-text. b) It sends one real message and multiple decoys to defeat attacks by providing security beyond conventional brute-force bounds. For both applications, AMSC can be used to deny encryption.