March 4, 2022
11:00am - 12:00pm
The Right to Deny On-Line Activities
Plausible deniability seems like the ultimate get-out-of-jail-free card. But how can we make it work when it comes to digital information sent in a public network. Deniable encryption, defined by Canetti et al (Crypto 1997), suggests a method to achieve deniability by the sender of encrypted messages to overcome this problem. The idea was especially interesting in the context of electronic elections to eliminate the threat of vote buying after a vote has been cast, except that their encryption scheme is not homomorphic which is necessary for encrypted vote adding and achieves only a 1/poly probability of being able to successfully deny unless the ciphertexts are not compact. Other examples come more largely where users store and compute on insecure platforms. I will present several new works on the subject: With S.Agarwal and S. Mossel (Crypto21) we define and construct sender Deniable Fully Homomorphic Encryption based on the Learning With Errors (LWE) polynomial hardness assumption; With S. Mossel and D. Wichs we show a public key encryption scheme which allows receivers of encrypted message to deny messages upto a set of edits of the message; With A. Coladangelo and U.Vazirani, we show a sender deniable encryption scheme where the encryption scheme is a quantum algorithm but the ciphertext is classical which is secure under the LWE polynomial hardness assumption.
Shafi Goldwasser is a renowned cryptographer, a recipient of a 2012 Turing Award for transformative work that laid the complexity-theoretic foundations for the science of cryptography. She is the RSA Professor of electrical engineering and computer science at the Massachusetts Institute of Technology, a professor of computer science and applied mathematics at Weizmann Institute of Science in Israel, and a director of the Simons Institute for the Theory of Computing at the University of California Berkeley. Shafi is also a co-founder and Chief Scientist of Duality, a company which pioneers efficient computation on encrypted data.