Sirvi Autor "Veri, Hans Kristjan" järgi

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Always Two, There Are: Towards Two-Party SDitH
(Tartu Ülikool, 2025) Veri, Hans Kristjan; Krips, Toomas, juhendaja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Arvutiteaduse instituut
The rise of quantum computing threatens to break many of the cryptographic systems that secure today’s digital world. In response, researchers are developing new tools designed to remain secure in a post-quantum future. Most of the promising candidates for post-quantum digital signatures rely on security assumptions based on lattices or properties of hash functions. Another promising approach transforms secure multi-party computation protocols into zero-knowledge proofs, which are then turned into digital signatures. This technique, known as multi-party computation in-the-head (MPCitH), offers strong security properties and flexibility for distributed applications. This thesis investigates whether MPCitH digital signatures can be efficiently adapted for use by two cooperating parties to jointly produce a signature. Here we show how to construct two-party signatures based on syndrome decoding in-the-head (SDitH) signatures. We propose a provably secure scheme that achieves the smallest known communication overhead among two-party MPCitH signatures, while resulting in a signature size approximately double that of a single-prover variant. This result provides a new data point in the design space of multi-party MPCitH signatures and post-quantum digital signatures in general.
Low-Complexity Decoding of Best Known Quasi-Cyclic Linear Codes
(Tartu Ülikool, 2023) Veri, Hans Kristjan; Bocharova, Irina, juhendaja; Kudryashov, Boris, juhendaja; Skachek, Vitaly, juhendaja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Arvutiteaduse instituut
Error-correcting codes are widely used in modern communications to detect and correct errors that can occur during the transmission of digital information. These codes help ensure reliable transmission by enabling the receiver to reconstruct the original information even if some bits of data were lost or corrupted during transmission. This thesis focuses on improving the decoding schemes of quasi-cyclic error-correcting codes. A classical theoretical framework is provided for understanding error-correcting codes. Quasi-cyclic codes which have the best parameters for given length are considered as generalized low-density parity-check codes to perform decoding. Exhaustive search for parity-check matrices of these codes is done to find ones as suitable as possible for iterative decoding. A new low-complexity decoding algorithm is proposed that uses multiple sub-decoders for the same code. It is shown that for a length 24 quasi-cyclic error-correcting code, this algorithm approaches the best achievable error rates and is competitive with previous results.
Vektorväärtustega Lipschitzi funktsioonide ruumi Daugaveti omadus
(Tartu Ülikool, 2025) Veri, Hans Kristjan; Haller, Rainis, juhendaja; Põldvere, Märt, juhendaja; Tartu Ülikool. Matemaatika ja statistika instituut; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
Bakalaureusetöös kirjutatakse üksikasjaliselt lahti järgmise R. Medina ja A. Rueda Zoca teoreemi [J. Funct. Anal., 2025; teoreem 1] tõestus. Teoreem. Kui M on täielik liinkaugusega nullpunktiga meetriline ruum ja X on Banachi ruum, siis ruumil Lip0(M, X) on Daugaveti omadus.