Q&A with Prof. Ashish Choudhury on Cryptography

Defined as the practice and study of techniques for secure communication, cryptography has started to gain importance and has become an important aspect of cyber security. In today’s computer-centric world, cryptography may be termed as the amalgamation of Mathematics and Computer Sciences. In general practice, algorithms are designed with utmost care, which the adversaries find hard to break. However, cryptography is generally associated with scrambling plaintext into ciphertext, then back again (known as decryption).

From questions about encryptions to ciphers to protocols, no one better to answer than an expert in the field himself. Prof. Ashish Choudhury joins us in an interesting conversation to decipher the concept of cryptography and emerging trends in this field.

1. What is the need of cryptography in an organisation?

Cryptography is a mathematical science, which deals with designing algorithms for ensuring information security. It plays the role of foundation for any secure system. Till the 1980s, the application of cryptography was limited only for military applications. But with the advent of Internet and digitalisation of the society, cryptography is now required on a daily basis. For example, while doing online transactions, you would like to maintain the privacy of your credit card details. While sending an email, the privacy of its contents needs to be maintained. You would like to deploy an authentication mechanism where only authorised person can enter a building or access some sensitive information and so on.

Even though Cryptography is a vast topic, the basic understanding of cryptographic algorithms is necessary before these algorithms are deployed in a real-world application.

2. Can you delve into the details of research work you’ve done in this field?

My main area of research is Secure Multi-Party Computation (SMPC) and the problem definition is as follows: there is a set of ’n’ mutually distrusting parties with their private inputs. The distrust among the parties is modelled by a centralised adversary who can corrupt a subset of parties. The parties would like to compute a publicly known function of their private inputs by keeping the inputs as private as possible. The goal is to design a protocol which allows the parties to do so. SMPC is considered to be the ‘Holy Grail’ of secure distributed computing, as it can abstract several secure distributed computing tasks. Over the last few years, I am working on designing efficient protocols for SMPC and other related tasks.

3. Tell us something about the latest developments and technologies used in this field?

As I mentioned earlier, cryptography is no longer limited to military applications and is now used widely on a daily basis. Naturally, a lot of development has happened over the last few years to make cryptography available on a day-to-day basis. Now we have fast encryption schemes and key exchange protocols, which allow secure communication within a fraction of a second. SMPC protocols are becoming a reality with several prototypes being developed. A very significant development in the cryptography arena is the invention of fully homomorphic encryption (FHE) schemes, which allows you to carry out any arbitrary computation on encrypted data, without revealing the data.

4. What, in your opinion, are some of the most interesting emerging trends in cryptography?

FHE and applied SMPC protocols are the two emerging trends which have generated lot of interest. Recently, blockchains, cryptocurrency and smart contracts have also emerged as interesting fields in the cryptography space.