Prof. Shweta Agrawal, CSE | "Real-life cryptography is cooler than Imitation Game-the movie"| Ep.13
Shweta Agrawal (guest), Unknown Host (host)
In this episode of Best Place To Build, featuring Shweta Agrawal and Unknown Host, Prof. Shweta Agrawal, CSE | "Real-life cryptography is cooler than Imitation Game-the movie"| Ep.13 explores modern cryptography, hard problems, encrypted computation, and building India’s research Cryptography is framed as the “art of keeping secrets,” enabling private communication, authentication, and secure protocols against algorithmic attackers.
Modern cryptography, hard problems, encrypted computation, and building India’s research
Cryptography is framed as the “art of keeping secrets,” enabling private communication, authentication, and secure protocols against algorithmic attackers.
Modern cryptography aims for mathematical, reduction-based security: breaking a scheme should be as hard as solving a well-studied hard problem.
Core ideas like efficient algorithms (polynomial time), hardness assumptions, and the P vs NP question are introduced as the conceptual basis for cryptographic security.
Agrawal’s research focus is computing on encrypted data via functional encryption and related primitives, with an emphasis on post-quantum (lattice-based) security.
The conversation broadens to computer science as “computing” (not just coding), India’s improving cryptography research ecosystem, the CyStar cybersecurity center at IIT Madras, and cultural issues like women’s retention in STEM and “Atma Shraddha” (self-belief).
Key Takeaways
Modern crypto security is about reductions to hard problems, not secrecy-by-obscurity.
Agrawal emphasizes that a secure scheme should be breakable only if an attacker can solve a specific, widely studied hard mathematical problem, giving stronger confidence than ad-hoc designs.
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“Attackers” in cryptography are modeled as algorithms with capabilities.
An eavesdropper is a passive attacker who listens, while a stronger attacker may also modify messages; defining these models precisely is central to security claims.
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Hardness means “no efficient probabilistic algorithm,” typically no polynomial-time solver.
In practice, “hard” is tuned to the application’s threat horizon (years to centuries), and security parameters are chosen so even massive classical compute can’t break it in reasonable time.
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Public-key encryption shifts the burden to protecting a single secret key.
With RSA-style public/secret keys, anyone can encrypt using the public key, but only the holder of the secret key can decrypt—so operational security focuses on safeguarding the private key.
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P vs NP underlies the possibility of cryptography, but specific assumptions drive real systems.
Cryptography requires some problems to be efficiently verifiable yet not efficiently solvable; while P vs NP is open, cryptographers rely on concrete conjectures backed by decades of analysis.
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Quantum algorithms change what counts as “hard,” so post-quantum design is needed now.
Even before practical quantum machines exist, known algorithms (e. ...
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Computing on encrypted data is possible only by balancing hidden structure with apparent randomness.
Ciphertexts must look like noise to attackers, yet contain enough algebraic structure to support authorized computations (add/multiply/ML-style processing) and correct decryption.
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Functional encryption enables “authorized outputs” rather than revealing raw data.
Instead of decrypting everything, users receive keys that only reveal a permitted function of the ciphertexts—e. ...
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Attribute-based encryption is functional encryption specialized to access control.
Decryption becomes conditional on attributes (e. ...
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Lattice-based cryptography is not just a quantum fix—it enables new capabilities.
Agrawal highlights lattices as both a post-quantum candidate foundation and a “door of opportunity” whose rich structure supports cryptography beyond earlier number-theoretic tools.
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Computer science is the science of computing, and programming is only one tool.
She distinguishes theory (complexity, cryptography), systems (OS, compilers, networks), and ML/AI, arguing that “CS = coding” is a misleading simplification.
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India’s public-key cryptography research capacity has grown sharply in ~10 years.
She notes increased representation at top venues (e. ...
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CyStar is designed to unify theory, bridging work, and applied security impact.
The center spans theoretical foundations, real-world models, and implementation/side-channel concerns, plus outreach (hackathons, winter schools) and talent development.
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Women’s underrepresentation grows with seniority, despite strong academic performance.
She cites evidence of higher average CGPAs for women at IITs and discusses bias in perceived leadership (the “head of the table” experiment) as a barrier to advancement.
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“Atma Shraddha” (self-belief) is presented as a strategic constraint on national progress.
Agrawal argues many students leave due to a default belief that excellence is “abroad,” urging informed choices based on objective fit rather than inherited inferiority narratives.
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Notable Quotes
“Calling our field computer science is like calling surgery knife science.”
— Shweta Agrawal
“Cryptography, in a sentence, is the art of keeping secrets.”
— Shweta Agrawal
“Modern cryptography seeks to... prove to you mathematically that the only way that you can break our code is by solving some very hard mathematical problem.”
— Shweta Agrawal
“Real-life cryptography is cooler than this movie.”
— Shweta Agrawal
“Cryptography is really this very fine dance between sort of structure and randomness.”
— Shweta Agrawal
Questions Answered in This Episode
When you say “prove security by reduction,” what does a reduction look like for a real scheme (step-by-step, conceptually)?
Cryptography is framed as the “art of keeping secrets,” enabling private communication, authentication, and secure protocols against algorithmic attackers.
Get the full analysis with uListen AI
In your view, what are the most common ways cryptosystems fail in practice despite strong theory (e.g., key handling, implementations, side channels)?
Modern cryptography aims for mathematical, reduction-based security: breaking a scheme should be as hard as solving a well-studied hard problem.
Get the full analysis with uListen AI
You described functional encryption keys that only open authorized computations—what prevents an analyst from combining multiple allowed functions to reconstruct the raw data?
Core ideas like efficient algorithms (polynomial time), hardness assumptions, and the P vs NP question are introduced as the conceptual basis for cryptographic security.
Get the full analysis with uListen AI
How does functional encryption differ from fully homomorphic encryption and secure multiparty computation in assumptions, efficiency, and deployment readiness?
Agrawal’s research focus is computing on encrypted data via functional encryption and related primitives, with an emphasis on post-quantum (lattice-based) security.
Get the full analysis with uListen AI
You mentioned RSA is easy for quantum computers—what are the concrete migration paths organizations should follow today (hybrid modes, timelines, standards)?
The conversation broadens to computer science as “computing” (not just coding), India’s improving cryptography research ecosystem, the CyStar cybersecurity center at IIT Madras, and cultural issues like women’s retention in STEM and “Atma Shraddha” (self-belief).
Get the full analysis with uListen AI
Transcript Preview
Calling our field computer science is like calling surgery knife science. Cryptography, in a sentence, is the art of keeping secrets. The desire to keep secrets is as old as humanity itself. Cryptography is really this very fine dance between sort of structure and randomness. I remember reading this algorithm as an undergrad and feeling that this is a life-changing moment. [upbeat music]
Hi, my name is Amrit. We've heard that IIT Madras is the best place to build. [upbeat music] So we've come down to the Sudha and Shankar Innovation Hub. We want to meet some people. These are builders. We want to talk to them about their work, and also ask them, what makes IIT Madras the best place to build? [upbeat music] Hi, welcome to the Best Place to Build Podcast. Today, we are sitting with Professor Shweta Agrawal. She's a professor of computer science at IIT Madras. Her area of interest is cryptography, so I've brought my ruled notebook to take notes. Uh, she holds the Venky Hariharan and Anand Rajaram Chair, and has won numerous awards, including the Swarnajayanti in 2020. Welcome, ma'am.
Thank you so much. It's good to be here.
Ma'am, let's start with, uh, what is cryptography? I think, uh, maybe it's obvious in your world, but it's completely alien to me.
So cryptography, in a sentence, is the art of keeping secrets. Uh, essentially, there are different goals that you might have, uh, such as, you know, wanting to communicate with someone in private, or when you're talking to someone, you, you may want to convince them that, you know, you are the person that they think, uh, they are talking to. So there are different goals that, uh, you might want to achieve in a secret manner, right? And cryptography is the science of enabling that.
So what I know of this, from whatever you said, is, uh... So I've watched Imitation Game, which is a movie about, uh-
Yeah
... about Alan Turing-
Right
... his team breaking the Enigma code. So c- can you tell us where we started from in cryptography and where we have come to?
Yeah, so cryptography, uh, is really an ancient field, though it may not have been, you know, uh, given, given this name until much more recently. But it's, uh... You know, the, the desire to keep secrets is as, uh, old as humanity itself, right? So y- you have, like, these very, very old codes, like the Caesar cipher and so on, where essentially if I want to say something in private to you, I replace each letter by, you know, the letter five steps ahead of it or something like that. So, uh, the field in, in its original form, I think has always existed, as long as humanity has existed. Uh, the movie you mentioned, and I mean, uh, the, the war and the efforts of building, uh, unbreakable codes, of course, took on, uh, like, a profound importance, uh, during that time. And, uh, the field as we know it is actually also, in a way, inspired from what happened, uh, during the war, which is that, uh, you know, a, a bunch of really smart people put together a really, uh, hard code to break, what they thought was a hard code to break, but they missed something, right? And that's what led to the, the break of the code. So modern cryptography seeks to kind of address this problem by saying that, "You know, we will prove to you mathematically that the only way that you can break our code is by solving some, you know, very hard mathematical problem." So in some sense, you know, all attack vectors can be reduced down to, like, this one question of: Can you solve so and so problem? And then if you choose this underlying problem as something that, you know, maybe mathematicians have tried for, like, decades, uh, and you have a lot of confidence that this problem is going to be very hard for any attacker, then you can have much more confidence that your code is secure.
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