Nikita Snetkov
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snetkovnikita.bsky.social
Nikita Snetkov
@snetkovnikita.bsky.social
50 followers 39 following 10 posts
Junior cryptography researcher at Cybernetica. PhD student at TalTech. Opinions are my own.
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snetkovnikita.bsky.social
My colleagues from Cybernetica and I decided to make another variant of Smart-ID / SplitKey protocol. Coppercloud is a two-party blind RSA signing with private key being split between a user and a server.
Perfect for the future of privacy-preserving digital wallets! 🌐✨
eprint.ing.bot ePrint Updates @eprint.ing.bot · Oct 8
Coppercloud: Blind Server-Supported RSA Signatures (Nikita Snetkov, Mihkel Jaas Karu, Jelizaveta Vakarjuk, Alisa Pankova) ia.cr/2025/1824
Abstract. Privacy-preserving technologies are a well-established area of research for the modern digital systems, driven by the regulatory mandates, such as the GDPR, and growing demand for the users’ privacy. One example from the different available technologies are blind signatures: a primitive that supports creation of privacy-sensitive applications, starting from secure e-voting and anonymous digital cash to privacy-preserving credentials and identity management systems. In this work, we introduce Coppercloud, a blind server-supported RSA signature scheme designed to enhance privacy in digital identity systems. Coppercloud enables a user to obtain a signature on a message, without revealing its content to the supporting server, while distributing the signing key between the user’s device and the supporting server. We formalize the security requirements for blind server-supported signing by defining an ideal functionality, and prove that Coppercloud securely realizes this functionality in the Universal Composability (UC) model.
October 8, 2025 at 10:24 AM
snetkovnikita.bsky.social
New paper written with my colleagues Jelizaveta Vakarjuk and Peeter Laud from Cybernetica just got accepted to ProvSec2025 🥳

In this paper, we aim to combine server-supported signatures together with fail-stop properties.

P.S. yes, protocol’s name is inspired by Mistborn series
eprint.ing.bot ePrint Updates @eprint.ing.bot · Jul 22
Electrum: UC Fail-Stop Server-Supported Signatures (Nikita Snetkov, Jelizaveta Vakarjuk, Peeter Laud) ia.cr/2025/1337
Abstract. Migration to quantum-safe cryptography represents a significant technological shift, addressing the vulnerabilities of traditional cryptographic primitives, such as KEMs and digital signatures. Yet, a number of challenges remain, especially in the development of secure solutions for sophisticated cryptographic applications. One of them is Smart-ID, European server-supported (threshold) signing service. To address this issue, we present Electrum, a fail-stop server-supported signature scheme designed to enhance security of existing Smart-ID service. Electrum combines multiprime RSA-based signatures with fail-stop features: providing not only unforgeability against classical adversaries but also allowing to prove that a given signature is a forgery made by classical and/or quantum adversaries. Proposed protocol can be seen as a temporary remedy against the quantum threat until standardised threshold signature schemes become a common practice. To prove security of Electrum, we introduce a new ideal functionality ℱ^(SplFS) for a fail-stop server-supported signing in the Universal Composability model. We show that Electrum protocol securely realizes the proposed functionality ℱ^(SplFS). Image showing part 2 of abstract.
July 23, 2025 at 8:25 AM
snetkovnikita.bsky.social
Thrilled to share a new paper written with my colleagues -- Trilithium (Star Trek reference is intended).

Our protocol is secure in UC model and allows two parties to construct FIPS compliant quantum-safe signature!
eprint.ing.bot ePrint Updates @eprint.ing.bot · Apr 15
Trilithium: Efficient and Universally Composable Distributed ML-DSA Signing (Antonín Dufka, Semjon Kravtšenko, Peeter Laud, Nikita Snetkov) ia.cr/2025/675
Abstract. In this paper, we present Trilithium: a protocol for distributed key generation and signing compliant with FIPS 204 (ML-DSA). Our protocol allows two parties, “server” and “phone” with assistance of correlated randomness provider (CRP) to produce a standard ML-DSA signature. We prove our protocol to be secure against a malicious server or phone in the universal composability (UC) model, introducing some novel techniques to argue the security of two-party secure computation protocols with active security against one party, but only active privacy against the other. We provide an implementation of our protocol in Rust and benchmark it, showing the practicality of the protocol.
April 15, 2025 at 1:28 PM
Reposted by Nikita Snetkov
tragiccommons.infosec.exchange.ap.brid.gy
We are now more than 30 years into the quantum computing hype. https://dl.acm.org/doi/pdf/10.1145/190616.190617 OMG it's the end of cryptography! zzz😴
January 8, 2025 at 7:43 PM
Reposted by Nikita Snetkov
claucece.bsky.social
Very excited to share our first exploration of threshold MAYO (yes, the PQC algorithm)! 🎉 Joint work with the amazing
Daniel Escudero and Guilhem Niot. The ideas can extend to UOV as well—let’s have MV-based threshold cryptography!

📄 eprint.iacr.org/2024/1960.pdf
December 6, 2024 at 4:34 PM
snetkovnikita.bsky.social
I don't know what impresses me more - BlueSky having ePrint updates or ePrint Updated Bot being able to find my profile and tag it 🤨
eprint.ing.bot ePrint Updates @eprint.ing.bot · Dec 2
Universally Composable Server-Supported Signatures for Smartphones (Nikita Snetkov, Jelizaveta Vakarjuk, Peeter Laud) ia.cr/2024/1941
Abstract. Smart-ID is an application for signing and authentication provided as a service to residents of Belgium, Estonia, Latvia and Lithuania. Its security relies on multi-prime server-supported RSA, password-authenticated key shares and clone detection mechanism. Unfortunately, the security properties of the underlying protocol have been specified only in “game-based” manner. There is no corresponding ideal functionality that the actual protocol is shown to securely realize in the universal composability (UC) framework. In this paper, we remedy that shortcoming, presenting the functionality (optionally parameterized with a non-threshold signature scheme) and prove that the existing Smart-ID protocol securely realizes it. Additionally, we present a server-supported protocol for generating ECDSA signatures and show that it also securely realizes the proposed ideal functionality in the Global Random Oracle Model (UC+GROM).
December 2, 2024 at 9:26 AM
snetkovnikita.bsky.social
The implementation for the TOPCOAT (link.springer.com/article/10.1...) is now public!!! Check it out at - github.com/ISRI-PQC/top...
November 20, 2024 at 9:51 AM