Simona Samardjiska

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1 Department of Telematics, Norwegian University of Science and Technology (NTNU), Trondheim, NORWAY, {danilog, simonas, hakoja} 2 “Ss Cyril and Methodius” University, Faculty of Computer Science and Engineering (FINKI), Skopje, MACEDONIA 3 Saint Petersburg State University of Aerospace Instrumentation, Saint(More)
This paper presents MQDSS, the first signature scheme with a security reduction based on the problem of solving a multivariate system of quadratic equations (MQ problem). In order to construct this scheme we give a new security reduction for the Fiat-Shamir transform from a large class of 5-pass identification schemes and show that a previous attempt from(More)
In this paper we describe two methods for constructing Multivariate Quadratic Quasigroups (MQQ) in Galois fields of any characteristic and order. Our constructions extend the previously known constructions defined for operations over the prime field of characteristic 2. Application of these new constructions can reduce the public key size of the recently(More)
In today’s world of big data and rapidly increasing telecommunications, using secure cryptographic primitives that are parallelizable and incremental is becoming ever more important design goal. π-Cipher is parallel, incremental, nonce based authenticated encryption cipher with associated data. It is designed with the special purpose of providing(More)
We propose a new multivariate probabilistic encryption scheme with decryption errors MQQ-ENC that belongs to the family of MQQ-based public key schemes. Similarly to MQQ-SIG, the trapdoor is constructed using quasigroup string transformations with multivariate quadratic quasigroups, and a minus modifier with relatively small and fixed number of removed(More)
We introduce a new family of binary linear codes suitable for steganographic matrix embedding. The main characteristic of the codes is the staircase random block structure of the generator matrix. We propose an efficient list decoding algorithm for the codes that finds a close codeword to a given random word. We provide both theoretical analysis of the(More)
Staircase-Generator codes (St-Gen codes) have recently been introduced in the design of code-based public key schemes and in the design of steganographic matrix embedding schemes. In this paper we propose a method for random splitting of St-Gen Codes and use it to design a new coding based public key encryption scheme. The scheme uses the known list(More)
We investigate the security of the family of MQQ public key cryptosystems using multivariate quadratic quasigroups (MQQ). These cryptosystems show especially good performance properties. In particular, the MQQ-SIG signature scheme is the fastest scheme in the ECRYPT benchmarking of cryptographic systems (eBACS). We show that both the signature scheme(More)
One of the crucial factors for enabling fast and secure computations in the Zettabyte era is the use of incremental cryptographic primitives. For files ranging from several megabytes up to hundreds of gigabytes, incremental cryptographic primitives offer speedup factors measured in multiple orders of magnitude. In this paper we define two incremental hash(More)
Recently we proposed a method for a random split of Staircase-Generator codes (StGen codes) to counter the weaknesses found in the previous constructions of public key schemes using St-Gen codes. The initial proposal for the random split addressed only the encryption scheme, and we left the problem of how to apply the random splitting on the signature(More)