CRC Seminar Series - Prof. Adi Shamir

Mar 16, 2023
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Adi Shamir

Prof. Adi Shamir

Tel Aviv University, Weizmann Institute of Science


16th March 2023, 4:00pm - 5:00pm (GST)



Facial Misrecognition Systems


In this talk I will describe how to plant novel types of backdoors in any facial recognition model based on the popular architecture of deep Siamese neural networks, by mathematically changing a small fraction of its weights (i.e., without using any additional training or optimization). These backdoors force the system to err only on specific persons which are preselected by the attacker. For example, we show how such a backdoored system can take any two images of a particular person and decide that they represent different persons (an anonymity attack), or take any two images of a particular pair of persons and decide that they represent the same person (a confusion attack), with almost no effect on the correctness of its decisions for other persons. Uniquely, we show that multiple backdoors can be independently installed by multiple attackers who may not be aware of each other’s existence with almost no interference. Joint work with Irad Zehavi.


Adi Shamir (Hebrew: עדי שמיר; born July 6, 1952) is an Israeli cryptographer. He is a co-inventor of the Rivest–Shamir–Adleman (RSA) algorithm (along with Ron Rivest and Len Adleman), a co-inventor of the Feige–Fiat–Shamir identification scheme (along with Uriel Feige and Amos Fiat), one of the inventors of differential cryptanalysis and has made numerous contributions to the fields of cryptography and computer science. Born in Tel Aviv, Shamir received a Bachelor of Science (BSc) degree in mathematics from Tel Aviv University in 1973 and obtained his Master of Science (MSc) and Doctor of Philosophy (PhD) degrees in Computer Science from the Weizmann Institute in 1975 and 1977 respectively. After a year as a postdoctoral researcher at the University of Warwick, he did research at Massachusetts Institute of Technology (MIT) from 1977 to 1980 before returning to be a member of the faculty of Mathematics and Computer Science at the Weizmann Institute. Starting from 2006, he is also an invited professor at École Normale Supérieure in Paris.

In addition to RSA, Shamir's other numerous inventions and contributions to cryptography include the Shamir secret sharing scheme, the breaking of the Merkle-Hellman knapsack cryptosystem, visual cryptography, and the TWIRL and TWINKLE factoring devices. Together with Eli Biham, he discovered differential cryptanalysis in the late 1980s, a general method for attacking block ciphers. It later emerged that differential cryptanalysis was already known — and kept a secret — by both IBM and the National Security Agency (NSA).

Shamir has also made contributions to computer science outside of cryptography, such as finding the first linear time algorithm for 2-satisfiability and showing the equivalence of the complexity classes PSPACE and IP.