Reza Ebrahimi Atani; Shahabaddin Ebrahimi Atani; A. Hassani Karbasi
Abstract
In this paper we present a new finite field-based public key cryptosystem(NETRU) which is a non-commutative variant of CTRU. The original CTRU is defined by the ring of polynomials in one variable over a finite field F2. This system works in the ring R = F2[x]=hxN 1i and is already broken ...
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In this paper we present a new finite field-based public key cryptosystem(NETRU) which is a non-commutative variant of CTRU. The original CTRU is defined by the ring of polynomials in one variable over a finite field F2. This system works in the ring R = F2[x]=hxN 1i and is already broken by some attacks such as linear algebra attack. We extend this system over finite fields Zp, where p is a prime (or prime power) and it operates over the non-commutative ring M = Mk(Zp)[T; x]=hXn Ikki, where M is a matrix ring of k by k matrices of polynomials in R = Zp[T; x]=hxn 1i. In the proposed NETRU, the encryption and decryption computations are non-commutative and hence the system is secure against linear algebra attack as lattice-based attacks. NETRU is designed based on the CTRU core and exhibits high levels of security with two-sided matrix multiplication.
R. Ebrahimi Atani; Sh. Ebrahimi Atani; A. Hassani Karbasi
Abstract
GGH class of public-key cryptosystems relies on computational problems based on the closest vector problem (CVP) in lattices for their security. The subject of lattice based cryptography is very active and there have recently been new ideas that revolutionized the field. We present EEH, a GGH-Like public ...
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GGH class of public-key cryptosystems relies on computational problems based on the closest vector problem (CVP) in lattices for their security. The subject of lattice based cryptography is very active and there have recently been new ideas that revolutionized the field. We present EEH, a GGH-Like public key cryptosystem based on the Eisenstein integers Z [ζ3] where ζ3 is a primitive cube root of unity. EEH applies representations of polynomials to the GGH encryption scheme and we discuss its key size and parameters selection. We also provide theoretical and experimental data to compare the security and efficiency of EEH to GGH with comparable parameter sets and show that EEH is an improvement over GGH in terms of security and efficiency.
A. Tavakoly; R. Ebrahimi Atani
Abstract
The Tor network is probably one of the most popular online anonymity systems in the world. It has been built based on the volunteer relays from all around the world. It has a strong scientific basis which is structured very well to work in low latency mode that makes it suitable for tasks such as web ...
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The Tor network is probably one of the most popular online anonymity systems in the world. It has been built based on the volunteer relays from all around the world. It has a strong scientific basis which is structured very well to work in low latency mode that makes it suitable for tasks such as web browsing. Despite the advantages, the low latency also makes Tor insecure against timing and traffic analysis attacks, which are the most dominant attacks on Tor network in recent past years. In this paper, first all kinds of attacks on Tor network will be classified and then timing and traffic analysis attacks will be described in more details. Then we present a new circuit scheduling for Tor network in order to preserve two properties, fairness and randomness. Both properties are trying to make pattern and timing analysis attacks more difficult and even in some cases impractical. Our scheduler distorts timing patterns and size of packets in a random way (randomness) without imposing artificial delays or paddings (fairness). Finally, by using our new scheduler, one of the most powerful attacks in this area is debilitated, and by it is shown that analyzing traffic patterns and size of packets will be more difficult to manage.