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Publicly Verifiable Ciphertexts

Nieto, JMG, Manulis, M, Poettering, B, Rangasamy, J and Stebila, D (2012) Publicly Verifiable Ciphertexts In: 8th International Conference, SCN 2012, 2012-09-05 - 2012-09-07, Amalfi, Italy.

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In many applications where encrypted traffic flows from an open (public) domain to a protected (private) domain there exists a gateway that bridges the two domains and faithfully forwards the incoming traffic to the receiver. We observe that indistinguishability against (adaptive) chosen-ciphertext attacks (IND-CCA), which is a mandatory goal in face of active attacks in a public domain, can be essentially relaxed to indistinguishability against chosen-plaintext attacks (IND-CPA) for ciphertexts once they pass the gateway that acts as an IND-CCA/CPA filter, by first checking the validity of an incoming IND-CCA ciphertext, then transforming it (if valid) into an IND-CPA ciphertext, and finally forwarding the latter to the recipient in the private domain. “Non-trivial filtering” can result in reduced decryption costs on the receiver’s side. We identify a class of encryption schemes with publicly verifiable ciphertexts that admit generic constructions of (non-trivial) IND-CCA/ CPA filters. These schemes are characterized by existence of public algorithms that can distinguish between valid and invalid ciphertexts. To this end, we formally define (non-trivial) public verifiability of ciphertexts for general encryption schemes, key encapsulation mechanisms, and hybrid encryption schemes, encompassing public-key, identity-based, and tag-based encryption flavors. We further analyze the security impact of public verifiability and discuss generic transformations and concrete constructions that enjoy this property.

Item Type: Conference or Workshop Item (Conference Paper)
Divisions : Faculty of Engineering and Physical Sciences > Computing Science
Authors :
Nieto, JMG
Manulis, M
Poettering, B
Rangasamy, J
Stebila, D
Date : 2012
DOI : 10.1007/978-3-642-32928-9_22
Contributors :
Additional Information : Coyright 2012 Springer-Verlag Berlin Heidelberg.The original publication is available at
Depositing User : Symplectic Elements
Date Deposited : 18 Oct 2013 15:57
Last Modified : 31 Oct 2017 16:23

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