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Aravind (Sri AravindaKrishnan Thyagarajan)

@aravind16coiner.bsky.social

Lecturer @sydney.edu.au @sydneycompsci.bsky.social SyCrypt Group: https://sydney-cryptography-group.github.io Previously PostDoc at NTT Research, CMU. PhD from FAU. Cryptography, Fairness, Blockchain, Cryptocurrency https://sak-thyagarajan.github.io

61 Posts275 Follower 97 Folgt

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 2mo ago

We organised the first edition of the cryptography school yesterday! Many students from diverse majors and a lot of fruitful discussions. Hope to spread the word on cryptography in the future as well. #Cryptography #UniSyd

School of Computer Science, University of Sydney@sydneycompsci.bsky.social · 3mo ago

🚨📣 Qiang Tang and @aravind16coiner.bsky.social are organising a one-day cryptography school on August 7, 2026. Open to UG, master's, and PhD students. Free attendance, but registration required! sydney-cryptography-group.github.io/activities-e...

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 3mo ago

Clément Canonne @ccanonne.github.io · 4mo ago

I have done a thing I'm very happy with (proposing the creation of a new course on quantum computing with @aravind16coiner.bsky.social), I think it's fair to call it a week.

Marcel Keller @mkskeller.bsky.social · 4mo ago

UNSW Sydney is hiring an associate professor and a lecturer in cryptography, and the description explicitly mentions *secure computation*. Didn't you want to live in the sunniest of the most livable cities in the world?

Associate Professor in Cryptography

Join an organisation that is shaping the future direction of cryptography and secure computation in Australia, in a senior academic role that combines research leadership, strategic contribution, and ...

external-careers.jobs.unsw.edu.au

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 4mo ago

We're hiring! As part of the "Women in Engineering" initiative at #USyd, the School of Computer Science is hiring women-identifying academics at Lecturer, Senior Lecturer, and A/Professor levels! (≈Asst, Assoc, and full prof) ⏰ Apply by July 13 (Sydney): usyd.wd105.myworkdayjobs.com/en-US/USYD_E...

Women in Engineering: Continuing (Tenure-Track) Academic Positions for Women, Faculty of Engineering, The University of Sydney

Join a growing Faculty and be part of a University that places amongst the world’s best teaching and research institutions Located in the heart of Sydney’s bustling inner west quarter, close to beache...

usyd.wd105.myworkdayjobs.com

ePrint Updates @eprint.ing.bot · 4mo ago

Cryptographic Collateralized Loan without Smart Contracts (Diego Castejon-Molina, Varun Madathil, Dimitrios Vasilopoulos, Sri AravindaKrishnan Thyagarajan, Pedro Moreno-Sanchez) ia.cr/2026/1123

Abstract. Cryptocurrency lending is growing rapidly, and smart-contract-based loans are expected to grow further. However, existing systems are fundamentally limited: they only operate on smart-contract-enabled blockchains, and assets from other blockchains can be used only via tokenized representations.

In this work, we propose an oracle-aided cryptographic protocol that implements the logic of collateralized loans without smart contracts, instead only requiring basic transactions from the underlying blockchain and hence, being compatible with limited-scripting blockchains, including Bitcoin.

For that, we introduce verifiable graph encryption for signatures (VGES), a new cryptographic primitive that, on input a graph modeling the correspondence between transactions for collateral distribution (vertices) and loan repayments (edges), permits to encrypt the signatures on collateral-distribution transactions ensuring: (1) a signature can only be decrypted after completing loan repayments corresponding to a valid path in the graph from the root (graph enforcement); and (2) anyone can verify that encrypted signatures are valid and can be decrypted after doing the required loan repayments according to the graph (verifiability).

We present two provably secure constructions of VGES and the evaluation of our implementation shows that they offer a tradeoff between the number of required on-chain transactions and off-chain computation, while both remain efficient on commodity hardware.

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 4mo ago

The paper is finally out! It was presented at IEEE SP this year. We show that functional fair exchange is possible to do efficiently! #adaptor #signatures

ePrint Updates@eprint.ing.bot · 4mo ago

New Constructions of Functional Adaptor Signatures: Broader Functions and Improved Efficiency (Nikhil Vanjani, Garrett Greiner, Sri AravindaKrishnan Thyagarajan, Pratik Soni) ia.cr/2026/1124

Abstract. Functional adaptor signatures (FAS) are a novel cryptographic primitive introduced at CCS’24 that enable privacy-preserving, fine-grained data-payment exchanges between a seller and a buyer in a trustless and atomic manner. In this setup, the seller holds sensitive data x (e.g., patient records, climate data), and the buyer specifies a function f (e.g., aggregate, sum). FAS guarantees that the buyer learns f(x) (and nothing beyond) if and only if the seller receives payment in blockchain-based tokens. Unlike generic smart contracts, FAS-powered solutions excel in privacy, efficiency, and compatibility with diverse blockchain systems. However, prior FAS constructions were limited to linear functions (where f was linear in x), restricting their applicability to more complex and prevalent applications including data analytics and ML model evaluations.

In this work, we extend the capabilities of FAS to support higher-degree functions (deg ≥ 2), significantly broadening its range of applications. Our core contribution is a novel FAS design leveraging homomorphic encryption, which simultaneously achieves enhanced efficiency and compatibility for general functions. This approach diverges fundamentally from the restricted design in CCS’24 which relied on connections to functional encryption. We implement our homomorphic encryption-based FAS for functions arising in applications such as data analytics and machine learning inference. Remarkably, even for linear functions, our new design achieves an order-of-magnitude improvement in performance compared to CCS’24 constructions. Furthermore, our solutions seamlessly integrate with prominent blockchain systems, requiring only a basic signature verification script on standard transactions, thus ensuring practical deployability. As a conceptual contribution, we introduce the general paradigm of a blockchain-based functional fair exchange (FFE) protocol, rigorously define buyer and seller fairness, and show that FAS implies the general goal of FFE.

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 4mo ago

We have been hiring healthy over the past cycles and if you are interested in coming down to Sydney and experiencing a more all round academic life, do get in touch. If you work on general CS topics and especially security, privacy, cryptography, blockchains etc, do apply!

School of Computer Science, University of Sydney@sydneycompsci.bsky.social · 4mo ago

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 4mo ago

I’m excited to share that I’ve received an Amazon Research Award for my proposal “Efficient Robust Post-Quantum Distributed Key Generation and Threshold Signatures”, at #USyd @sydneycompsci.bsky.social @sydney.edu.au About the program: www.amazon.science/research-awa... #AmazonResearchAwards

Amazon Research Awards

Collaborating with scientists around the globe to fund research, share knowledge and encourage innovation.

amazon.science

Dom Williamson @domwilliamson.bsky.social · 5mo ago

Very excited to explore new roads to fault-tolerant photonic quantum computation with PsiQuantum! rms.arc.gov.au/RMS/Report/D... @arc-gov-au.bsky.social @sydney.edu.au @psiquantum.bsky.social @bartlettquantum.bsky.social @acdoherty.bsky.social @jcbridgeman1.bsky.social @quantum-roberts.bsky.social

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 5mo ago

Wonderful time at the 🏆 2026 School of Computer Science annual awards ceremony last Tuesday, where academics and staff gathered to celebrate the exceptional achievements and outstanding contributions of our students! A few of the many highlights below—and so much talent! 🎓 #USyd

Prof. Tony Wirth, Head of School, kicking off the ceremony

A group of 6 students, presented with their awards: the Microsoft Research Asia Prize for Senior Software Development Projects

The audience in the Holme refectory, where the ceremony was held

A group of 5 students who were awarded the Undergraduate High Honour Roll, presented with their certificate by Dr. Nataliia Stratiienko

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 5mo ago

🏆 Our PhD student Linwei Tao has been selected as an Apple Scholar in AIML, a fellowship recognising emerging leaders in #AI and #MachineLearning! Linwei is one of only 20 scholars in 2026, and the first recipient from an Australian University! Read more: machinelearning.apple.com/updates/appl...

Announcing the 2026 Apple Scholars in AIML

The Apple Scholars in AIML PhD fellowship program supports emerging leaders in academic research through funding as they pursue their PhDs…

machinelearning.apple.com

Nils Fleischhacker @cryptomaeher.bsky.social · 5mo ago

My time at RUB is coming to an end and I'm looking for an industry position. Primarily looking for remote or Rhine-Ruhr area positions, but will consider any exceptional offers. So if you're looking to hire a cryptographer to work on cryptographic protocols, or related areas, maybe we should talk!

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 5mo ago

We show how to do wagers or probabilistic cross chain swaps on Bitcoin. Say you have x LTC tokens, and you want to swap it for 1 BTC. But you get the BTC only with some probability. So if you like the odds, you can now bet your tokens to enter into more stable systems. #Bitcoin #crypto #swap

ePrint Updates@eprint.ing.bot · 5mo ago

Probabilistic Atomic Swaps for Bitcoin and Friends (Paul Gerhart, Jay Taylor, Sri Aravinda Krishnan Thyagarajan) ia.cr/2026/887

Abstract. Atomic swaps are a fundamental primitive for the trustless exchange of digital assets across blockchains: they guarantee that either both parties receive the agreed assets or neither party transfers. While this all-or-nothing guarantee is powerful, it also imposes an inherent determinism that rules out exchanges whose intended outcome is probabilistic. As a result, existing atomic swaps cannot realize trustless exchanges in which one party pays for a fixed chance of receiving a larger asset or reward, as in lotteries, randomized allocation mechanisms, and probabilistic cross-chain trades.

We introduce probabilistic swaps, a new cryptographic primitive that extends atomic swaps to the probabilistic setting. In a probabilistic swap, one party’s transfer is executed with a fixed, publicly specified probability embedded in the protocol and cannot be biased by either party. This yields a trustless mechanism for randomized exchange with verifiable odds and no trusted intermediary.

Our construction combines adaptor signatures with oblivious pseudorandom functions (OPRFs) to realize the desired probabilistic outcome while ensuring that neither party can predict or bias it in advance. Along the way, we introduce a new mechanism for the atomic exchange of OPRF evaluations for payments, which may be of independent interest. A key feature of our approach is that it preserves the minimal on-chain footprint of modern atomic-swap protocols. The protocol relies only on standard Bitcoin scripts, such as digital signatures and timelocks, and is deployable on any blockchain that already supports atomic swaps. Consequently, probabilistic swaps are indistinguishable from ordinary on-chain transactions, which helps preserve privacy and fungibility. We provide formal security foundations and demonstrate practicality through a probabilistic swap between the Bitcoin and Litecoin testnets, as well as in the Lightning Network.

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 5mo ago

🎉 Andre Van Renssen's paper "Visibility Queries in Simple Polygons" has been accepted at #ICALP! #computationalgeometry 🔗 More about ICALP: icalppodcspaa2026.cs.rhul.ac.uk/icalp/ arxiv.org/pdf/2605.03334

Sydney Mathematical Research Institute (SMRI)@sydmathinst.bsky.social · 5mo ago

@monsoon0.bsky.social's fundamental research in the mathematical sciences is our weapon against cryptographic breakdown of our current security systems protecting your personal and financial information 🔐 Check out the episode of The Solutionists here: www.sydney.edu.au/news-opinion... #MathSky

The Solutionists with Mark Scott

The Solutionists is a podcast from The University of Sydney, hosted by Vice-Chancellor and President Mark Scott.

sydney.edu.au

Nalini Joshi@monsoon0.bsky.social · 5mo ago

I did a podcast with my Vice-Chancellor @sydney.edu.au go.sydney.edu.au/H7FkmC #thesolutionists

Nalini Joshi @monsoon0.bsky.social · 5mo ago

I did a podcast with my Vice-Chancellor @sydney.edu.au go.sydney.edu.au/H7FkmC #thesolutionists

go.sydney.edu.au

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 5mo ago

Follow the handle @sydneycompsci.bsky.social for exciting updates on CS research conducted at #USyd @sydney.edu.au !!!!

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 5mo ago

🎉 Hanwen Feng, Qiang Tang, and Sri AravindaKrishnan Thyagarajan's paper " Anchor-DKG: Distributed Key Generation with Repeating Parties" has been accepted at #CCS2026! #cryptography #dkg 🔗 More about ACM CCS 2026: www.sigsac.org/ccs/CCS2026/ 👤 @alkist.bsky.social @aravind16coiner.bsky.social

Computational Geometry

computational-geometry.org

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 5mo ago

🎉 Sri AravindaKrishnan Thyagarajan's paper "When Threshold Meets Anamorphic Signatures: What is Possible and What is Not!" has been accepted at #PoPETS2026! #anamorphic #communication #privacy 🔗 More about PoPETS 2026: petsymposium.org/2026/ 👤 @aravind16coiner.bsky.social

ACM CCS 2026

CCS2026

sigsac.org

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 5mo ago

Want to work with us on threshold cryptography? Get in touch! #threshold #cryptography #phd

School of Computer Science, University of Sydney@sydneycompsci.bsky.social · 5mo ago

🏆 Congratulations to Qiang Tang (@alkist.bsky.social) and Sri AravindaKrishnan Thyagarajan (@aravind16coiner.bsky.social), who were awarded a grant by the Stellar Development Foundation on "Enabling Scalable Threshold Cryptography For Federated Settings"!

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 5mo ago

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 6mo ago

📢 📢 📢 🚨 I am looking for two PhD students to hire in post quantum cryptography. Exciting opportunity to work at University of Sydney @sydneycompsci.bsky.social and the theory/crypto groups here. Do share with your students and contacts. #hiring #phd #pqc #cryptography 🔗 iacr.org/jobs/item/4199

Two PhD Positions in Post-Quantum Cryptography (PQC)

iacr.org

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 7mo ago

Here's the paper eprint.iacr.org/2026/395 that my student Jay @ezepze.bsky.social will present at #FC2026 this week. He will talk about how to make delegated payments on Bitcoin. A question relevant for the AI agentic future. This was part of Jay's UG thesis.

How To Make Delegated Payments on Bitcoin: A Question for the AI Agentic Future

AI agents and custodial services are increasingly being entrusted as intermediaries to conduct transactions on behalf of institutions. The stakes are high: The digital asset market is projected to exc...

eprint.iacr.org

Aravind (Sri AravindaKrishnan Thyagarajan)@aravind16coiner.bsky.social · 8mo ago

Jay ( @ezepze.bsky.social ) will present the paper in St. Kitts #FC2026

School of Computer Science, University of Sydney@sydneycompsci.bsky.social · 8mo ago

🎉 Jay Taylor (UG Honor's student) and Sri AravindaKrishnan Thiagarajan (@aravind16coiner.bsky.social)'s paper "How To Make Delegated Payments on Bitcoin: A Question for the AI Agentic Future" has been accepted at #FC2026! 🔗 FC 2026: ifca.ai/fc26/ #Blockchain #Bitcoin #Cryptography #AgenticPayments

School of Computer Science, University of Sydney @sydneycompsci.bsky.social · 10mo ago

🎉Congratulations to Aravind (@aravind16coiner.bsky.social), on being awarded an USD 25k grant by the SUI Foundation for "Sequential Conditional Payments Across Blockchains With Minimal Contracts"! #Blockchain

Clément Canonne @ccanonne.github.io · 10mo ago

Fantastic talk by Shafi Goldwasser at #USyd, to a packed auditorium!

Shafi, being introduced by the Dean of Engineering, Hesham El Gamal

Sydney Mathematical Research Institute (SMRI)@sydmathinst.bsky.social · 10mo ago

Our special Basser-SMRI Seminar with @sydneycompsci.bsky.social is now on YouTube: Is Dijkstra’s Algorithm Optimal? — Robert Tarjan, Princeton University youtu.be/Pc40q0JGdjc

Is Dijkstra’s Algorithm Optimal?

YouTube video by Sydney Mathematical Research Institute - SMRI

youtu.be

Sydney Mathematics and Statistics @sydneymathsstats.bsky.social · 10mo ago

Congratulations to @monsoon0.bsky.social, Geordie Williamson, @tillus.bsky.social, John Voight from the School of Mathematics at USyd, and the rest of the team, from other parts of university and beyond, for their ARC Centre of Excellence in Mathematics for Quantum Era Security and Trust!

Clément Canonne @ccanonne.github.io · 10mo ago

Thrilled to be part of this new ARC Centre of Excellence, led by Prof. Nalini Joshi (@monsoon0.bsky.social) at #USyd: ARC Centre of Excellence in Mathematics for #Quantum Era Security and Trust (MathQUEST)!

ARC Centre of Excellence in Mathematics for Quantum Era Security and Trust. The ARC Centre of Excellence in Mathematics for Quantum Era Security and Trust (MathQuEST) strives to build critical expertise to protect against the expected breakdown of cybersecurity protocols on quantum computers and build trust in artifical intelligence. Deep, untapped reservoirs of mathematical problems and structures will be mined to establish complexity foundations for security and create accelerated methods for AI. MathQuEST will assemble leading researchers from diverse disciplines to deliver a mathematically trained, technologically agile workforce, ensuring Australia’s preparedness for grand challenges arising from future quantum computers with dual-use impact across agriculture, defence, health and industry.