Chennai Mathematical Institute


11:45 am, Lecture Hall 2
Constructing cryptography for the cloud

Shweta Agrawal
Inspire Fellow, IIT Delhi.


We live in technologically exciting times. The big data revolution promises technology bordering on science fiction -- personalised medicine via genome sequencing, the "internet of things" offering the potential of smart cities, smart appliances for healthcare, smart metering and many such applications. But as our technology has increased, so has our vulnerability. In the age of Wikileaks and Snowden, we worry increasingly about the security of our data and about our privacy at large. Can we enable technology while still having reasonable guarantees on security? This is a complex question and we study how cryptography can offer solutions to the demands placed by the above applications.

In this talk, I will discuss two recent results that offer solutions that are well suited to applications such as the above. In the first work. I will describe some recent work in the construction of novel encryption schemes that generalise and extend public key encryption. An attractive feature of one of our constructions is an "online-offline" property, that enables the encryptor to do a large amount of work before it receives the data, i.e. "offline", so that encryption is very efficient after data becomes available. This makes the construction suitable for streaming data applications.

In the second work, I will describe an encryption scheme that operates on data of dynamic length. Thus the length of the message being encrypted can be chosen at run time. In our scheme, the secret key is associated with a deterministic finite automata M and the ciphertext is associated with an input x of arbitrary length. The decryptor, given SK(M) and CT(x) learns M(x) and nothing else. Our solution is useful for datasets of sensitive information that have dynamically changing sizes.