OHIE: Blockchain Scaling Made Simple

Many blockchain consensus protocols have been proposed recently to scale the throughput of a blockchain with available bandwidth. However, these protocols are becoming increasingly complex, making it more and more difficult to produce proofs of their security guarantees. We propose a novel permissionless blockchain protocol OHIE which explicitly aims for simplicity. OHIE composes as many parallel instances of Bitcoin's original (and simple) backbone protocol as needed to achieve excellent throughput. We formally prove the safety and liveness properties of OHIE. We demonstrate its performance with a prototype implementation and large-scale experiments with up to 50,000 nodes. In our experiments, OHIE achieves linear scaling with available bandwidth, providing about 4-10 Mbps transaction throughput (under 8-20 Mbps per-node available bandwidth configurations) and at least about 20x better decentralization over prior works

Cryptanalysis of EnRUPT

In this paper we present a preimage attack on EnRUPT-512. We exploit the fact that the internal state is only a little bit larger than the critical security level: 1152 bits against 1024 bits. The absence of a message expansion and a fairly simple compression function allow us to fix the values for some state words and thus reduce the size of birthday state space in the meet-in-the-middle attack under 1024 bits. Equations that arise through the analysis are solved using look-up tables. The complexity of the attack is around 2^{480} compression function calls and the memory requirement is around 2^{384}

Refinements of the k-tree Algorithm for the Generalized Birthday Problem

We study two open problems proposed by Wagner in his seminal work on the generalized birthday problem. First, with the use of multicollisions, we improve Wagner\u27s $3$-tree algorithm. The new 3-tree only slightly outperforms Wagner\u27s 3-tree, however, in some applications this suffices, and as a proof of concept, we apply the new algorithm to slightly reduce the security of two CAESAR proposals. Next, with the use of multiple collisions based on Hellman\u27s table, we give improvements to the best known time-memory tradeoffs for the k-tree. As a result, we obtain the a new tradeoff curve T^2 \cdot M^{\lg k -1} = k \cdot N. For instance, when k=4, the tradeoff has the form T^2 M = 4 \cdot N

Efficient Design Strategies Based on the AES Round Function

We show several constructions based on the AES round function that can be used as building blocks for MACs and authenticated encryption schemes. They are found by a search of the space of all secure constructions based on an efficient design strategy that has been shown to be one of the most optimal among all the considered. We implement the constructions on the latest Intel\u27s processors. Our benchmarks show that on Intel Skylake the smallest construction runs at 0.188 c/B, while the fastest at only 0.125 c/B, i.e. five times faster than AES-128

Performance Analysis of Industrial Cooperative Communication System in Generalized Fading Environment

This paper considers the performance analysis of M-ary phase shift keying industrial cooperative relaying system in Nakagami-m multipath fading channel with Gamma shadowing, which is known as the Generalized-K composite fading channel. Since the paper deals with the industrial environment, the communication channel is also affected by the additive Middleton\u27s Class-A impulsive noise. The bit error rate is used as a performance measure and the closed-form average bit error rate expression was derived. The influence of different fading and noise parameters on the system performance is investigated. The obtained results may be used for the improvement of the present and future industrial wireless communication systems

Pre-crisis reforms, austerity measures and the public-private wage gap in two emerging economies

This paper analyzes crisis adjustments of the public and private sectors in two emerging market economies, Croatia and Serbia, during the 2008–2011 period. It focuses on public-private wage gaps at the onset of and during the crisis, decomposed into structural and composition effects using an extension to the Oaxaca-Blinder method based on Recentered Influence Function (RIF) regressions and reweighting. The main results indicate that at the beginning of the crisis public sector workers in both countries enjoyed a significant wage premium, with the premium in Serbia being about three times higher than in Croatia. During the crisis, both countries experienced a similar increase of the premium, with Croatia reaching the size of gap usually estimated for EU countries, while Serbia stayed largely ahead. The results also show that the wage distribution in the public sector is more compressed than in the private sector in both countries, which is further exacerbated by the crisis. Despite the introduced austerity measures, public sector workers continue to enjoy well-protected and privileged jobs in terms of wages relative to their private sector counterparts. Structural reforms undertaken prior to the crisis played a decisive role in determining the countries’ responses to the crisis

Boomerang Attacks on BLAKE-32

We present high probability differential trails on 2 and 3 rounds of BLAKE-32. Using the trails we are able to launch boomerang attacks on up to 8 round-reduced keyed permutation of BLAKE-32. Also, we show that boomerangs can be used as distinguishers for hash/compression functions and present such distinguishers for the compression function of BLAKE-32 reduced to 7 rounds. Since our distinguishers on up to 6 round-reduced keyed permutation of BLAKE-32 are practical (complexity of only 212 encryptions), we are able to find boomerang quartets on a PC