Igors Stepanovs

I am interested in practice-oriented cryptography. My ongoing and recently completed projects focus on providing formal security analysis of novel cryptographic algorithms that are deployed in widely used software.

I currently work at Amazon. Previously I worked as a postdoctoral researcher in the Applied Cryptography Group at ETH Zürich led by Kenny Paterson. I earned a PhD in Computer Science at UC San Diego advised by Mihir Bellare. Prior to starting my doctoral studies, I obtained BSc and MSc in Computer Science at University of Latvia, and MSc in Mathematics of Cryptography and Communcations at Royal Holloway, University of London.

I worked as a software developer during my university studies. In one of my roles, I participated in the development of a whitebox cryptography library. I provide more information in my CV.

Publications (Google Scholar profile)

Symmetric Signcryption and E2EE Group Messaging in Keybase
Joseph Jaeger, Akshaya Kumar, Igors Stepanovs. EUROCRYPT 2024.

Four Attacks and a Proof for Telegram
Martin R. Albrecht, Lenka Mareková, Kenneth G. Paterson, Igors Stepanovs. IEEE S&P 2022 (Distinguished Paper Award).
webpage; talk by Lenka Mareková; my slides from the Joint Latvian-Estonian Theory Days 2022; my online talk and slides from RWC 2022; my comments in popular press.

Security under Message-Derived Keys: Signcryption in iMessage
Mihir Bellare, Igors Stepanovs. EUROCRYPT 2020.
my pre-recorded talk and slides.

On the Security of Two-Round Multi-Signatures
Manu Drijvers, Kasra Edalatnejad, Bryan Ford, Eike Kiltz, Julian Loss, Gregory Neven, Igors Stepanovs. IEEE S&P 2019.
talk by Manu Drijvers.

Optimal Channel Security Against Fine-Grained State Compromise: The Safety of Messaging
Joseph Jaeger, Igors Stepanovs. CRYPTO 2018.
talk by Joseph Jaeger.

Forward-Security under Continual Leakage
Mihir Bellare, Adam O'Neill, Igors Stepanovs. CANS 2017.

Ratcheted Encryption and Key Exchange: The Security of Messaging
Mihir Bellare, Asha Camper Singh, Joseph Jaeger, Maya Nyayapati, Igors Stepanovs. CRYPTO 2017.
talk by Joseph Jaeger.

New Negative Results on Differing-Inputs Obfuscation
Mihir Bellare, Igors Stepanovs, Brent Waters. EUROCRYPT 2016.
my (truncated) talk and slides.

Contention in Cryptoland: Obfuscation, Leakage and UCE
Mihir Bellare, Igors Stepanovs, Stefano Tessaro. TCC 2016-A.
talk by Stefano Tessaro at the Simons Workshop on Securing Computation in June 2015; my slides (combined for two papers) from TCC 2016-A.

Point-Function Obfuscation: A Framework and Generic Constructions
Mihir Bellare, Igors Stepanovs. TCC 2016-A.
my slides (combined for two papers).

Poly-Many Hardcore Bits for Any One-Way Function and a Framework for Differing-Inputs Obfuscation
Mihir Bellare, Igors Stepanovs, Stefano Tessaro. ASIACRYPT 2014.
my slides.

Advising and Academic Service

Advising: Tijana Klimovic (ETH Zürich, MSc thesis, Mar 2021–Sep 2021). "Modular Design of the Messaging Layer Security (MLS) Protocol". Co-Advisor: Kenneth G. Paterson.

Program committee (PC) memberships: PKC 2022.

Peer review for scientific conferences:


TA appointments at ETH Zürich:

TA appointments at UC San Diego:

I taught programming to groups of high school students in 2007–2010 and 2012–2013, as a part-time job at Progmeistars.


A technical description and a toy implementation of an LWE-based FHE scheme.
My project for the lattice class taught by Daniele Micciancio at UC San Diego in Spring 2014. The scheme was defined in class and is roughly based on GSW13, BV14, AP14.

Selected Relations Between Obfuscation Notions
A diagram that presents some of the results from my TCC 2016-A and EUROCRYPT 2016 papers in the context of prior work.

Survey of Fully Homomorphic Encryption
Igors Stepanovs. MSc dissertation, Royal Holloway, University of London, 2012.

Query Complexity of Boolean Functions with Low Polynomial Degree (in Latvian)
Igors Stepanovs. MSc thesis, University of Latvia, 2012.
my slides from the Joint Estonian-Latvian Theory Days 2012.

Query Complexity of Boolean Functions with Low Polynomial Degree (in Latvian)
Igors Stepanovs. BSc thesis, University of Latvia, 2010.