Modern cryptography provides strong security guarantees via mathematical proofs. One major challenge is to define realistic formal models in which security of cryptographic systems can be proven and which at the same time cover real-world needs and threats. Researchers at MIT have tackled the question of providing better and strong security models for central and emerging cryptographic tasks which have been so far lacking appropriate modeling, like distributed cryptographic protocols, physical-layer security and password-based cryptography.



Micciancio, D., and Tessaro, S. “An Equational Approach to Secure Multi-Party Computation.” Innovations in Theoretical Computer Science - ITCS 2013.

Bellare, M., Ristenpart, T., and Tessaro, S. “Multi-Instance Security and its Application to Password-Based Cryptography.” Advances in Cryptology -- CRYPTO 2012. LNCS, vol. 7417, pp. 312–329, Aug 2012.

Bellare, M., Tessaro, S., and Vardy, A. “Semantic Security for the Wiretap Channel.” Advances in Cryptology -- CRYPTO 2012. LNCS, vol. 7417, pp. 294–311, Aug 2012. [Video]



In the real-world, the security of cryptographic systems may end up being reduced for different reasons: Better attacks may weaken computational assumptions underlying the security of these systems, and implementation errors may lead to both security vulnerabilities as well as incorrect behavior of cryptographic algorithms. The area of security amplification deals with protecting cryptographic systems from such vulnerabilities by providing efficient methods to transform possibly weak cryptosystems into strongly secure ones. 

Researchers at MIT have recently made several advances in the theory of security amplification for different form of encryption algorithms. 



Lin, H., and Tessaro, S. “Amplification of Chosen-Ciphertext Security.” Advances in Cryptology -- EUROCRYPT 2013. May 2013. (To appear).

Gazi, P., and Tessaro, S. “Efficient and Optimally Secure Key-Length Extension for Block Ciphers via Randomized Cascading.”Advances in Cryptology -- EUROCRYPT 2012. LNCS, vol. 7327, pp. 63–80, Apr 2012.

Tessaro, S. “Security Amplification for the Cascade of Arbitrarily Weak PRPs: Tight Bounds via the Interactive Hardcore Lemma.” Theory of Cryptography — TCC 2011, LNCS, vol. 6597, pp. 37–54, Mar 2011.