Cryptology ePrint Archive: Report 2017/1140

Lattice Klepto: Turning Post-Quantum Crypto Against Itself

Robin Kwant and Tanja Lange and Kimberley Thissen

Abstract: This paper studies ways to backdoor lattice-based systems following Young and Yung's work on backdooring RSA and discrete-log based systems. For the NTRU encryption scheme we show how to build a backdoor and to change the system so that each ciphertext leaks information about the plaintext to the owner of the backdoor. For signature schemes the backdoor leaks information about the signing key to the backdoor owner.

As in Young and Yung's work the backdoor uses the freedom that random selections offer in the protocol to hide a secret message encrypted to the backdoor owner. The most interesting and very different part though is how to hide and retrieve the hidden messages.

Category / Keywords: public-key cryptography / Post-quantum cryptography, kleptography, lattice-based encryption, NTRU, signatures

Original Publication (with minor differences): Selected Areas in Cryptography 2017

Date: received 24 Nov 2017

Contact author: k k a thissen at student tue nl

Available format(s): PDF | BibTeX Citation

Version: 20171127:133018 (All versions of this report)

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