Skip to main content
Realizing Sender’s Deniability in Public Key Encryption via Random Coins Isolation
European Journal of Scientific Research (2014)
  • Maged Ibrahim, Helwan University
Deniable encryption allows a sender and/or a receiver to escape a coercion attempted by a potential coercive adversary. It also prevents a malicious user from misusing his rights by sending to a receiver a particular encrypted message (against his own belief) satisfactory to the coercer in order to benefit from such action (e.g. gaining some cash in return). Therefore, deniable encryption must be receipt-free in the sense that it must disable the ability of the user to prove to the coercer the message that will be decrypted by the receiver. Almost all previous contributions to design a deniable public- key encryption scheme are based on the idea of constructing an encryption scheme that allows the sender to open a fake message and random coins to an adversary that when verified using the receiver's public key gives the same ciphertext as the true message. Although such approach is challenging, none of the previously proposed schemes achieves the desired level of deniability in the sense that they are not receipt-free. On the other hand they do not benefit from the efficiency and security properties of existing standard cryptosystems (e.g. homomorphic properties, semantic security, chosen text security, constant transmission rate, etc.). In this paper we introduce a new approach to realize sender’s deniability in public-key encryption. Our approach is to isolate the generation of the random coins from the sender and to force the sender to (blindly) use the isolated random coins to perform the encryption or else, an honest receiver will not accept the decrypted message. Our approach converts any existing conventional public- key cryptosystem to a sender-deniable public-key cryptosystem while preserving all the features of this cryptosystem.
  • Smart-Cards,
  • Deniable Encryption,
  • Incoercible Encryption,
  • Public-Key Cryptosystems,
  • Receipt freeness,
  • E-voting,
  • E-auctions,
  • E-commerce.
Publication Date
January, 2014
Citation Information
Maged Ibrahim. "Realizing Sender’s Deniability in Public Key Encryption via Random Coins Isolation" European Journal of Scientific Research Vol. 119 Iss. 2 (2014) p. 177 - 187
Available at: