On the Collision and Preimage Resistance of Certain Two-Call Hash Functions

In this paper we present concrete collision and preimage attacks on a large class of compression function constructions making two calls to the underlying ideal primitives. The complexity of the collision attack is above the theoretical lower bound for constructions of this type, but below the birthday complexity; the complexity of the preimage attack, however, is equal to the theoretical lower bound. We also present undesirable properties of some of Stam’s compression functions proposed at CRYPTO ’08. We show that when one of the n-bit to n-bit components of the proposed 2n-bit to n-bit compression function is replaced by a fixed-key cipher in the Davies-Meyer mode, the complexity of finding a preimage would be 2 n/3. We also show that the complexity of finding a collision in a variant of the 3n-bits to 2n-bits scheme with its output truncated to 3n/2 bits is 2 n/2. The complexity of our preimage attack on this hash function is about 2 n . Finally, we present a collision attack on a variant of the proposed m + s-bit to s-bit scheme, truncated to s − 1 bits, with a complexity of O(1). However, none of our results compromise Stam’s security claims.

Forgery attacks on ++AE authenticated encryption mode

In this paper, we analyse a block cipher mode of operation submitted in 2014 to the cryptographic competition for authenticated encryption (CAESAR). This mode is designed by Recacha and called ++AE (plus-plus-ae). We propose a chosen plaintext forgery attack on ++AE that requires only a single chosen message query to allow an attacker to construct multiple forged messages. Our attack is deterministic and guaranteed to pass ++AE integrity check. We demonstrate the forgery attack using 128-bit AES as the underlying block cipher. Hence, ++AE is insecure as an authenticated encryption mode of operation.

The 1958 pearl oyster fishery, Gulf of Mannar

The continental shelf between the three and twelve fathom lines, off the Ceylon coast in the Gulf of Mannar is popularly known as the Pearl Banks. Though the area of this plateau is extensive the pearl oysters are concentrated on restricted areas known as "paars". The more productive of these are the Cheval Group of paars and the Moderagam Paar. The Peria Paar and Twynam's Paar though covering larger areas are not dependable as oyster beds. The True Vankalai, Peria Paar Karai and Muthuvarathu Paars are small in extent, but have yielded oysters on a commercial scale. Although the Ceylon Pearl Banks has been commercially fished for centuries, the first scientific investigation of its pearl oysters on an intensive scale was started by Herdman in 1902 (1902-06) and later continued by Hornell (1905-41), Shipley (1904-06), Pearson (1911-33), Jameson (1912-13), Southwell (1910-14) and Malpas (1922-39).

On a Certain Algebraic Property of Block Ciphers

This is a study on a certain group theoretic property of the set of encryption functions of a block cipher. We have shown how to construct a subset which has this property in a given symmetric group by a computer algebra software GAP4.2 (Groups, Algorithms, and Programming, Version 4.2). These observations on group structures of block ciphers suggest us that we may be able to set a trapdoor based on meet-in-the-middle attack on block ciphers.

Evaluation of TFTP DDoS Amplification Attack.

Web threats are becoming a major issue for both governments and companies. Generally, web threats increased as much as 600% during last year (WebSense, 2013). This appears to be a significant issue, since many major businesses seem to provide these services. Denial of Service (DoS) attacks are one of the most significant web threats and generally their aim is to waste the resources of the target machine (Mirkovic & Reiher, 2004). Dis-tributed Denial of Service (DDoS) attacks are typically executed from many sources and can result in large traf-fic flows. During last year 11% of DDoS attacks were over 60 Gbps (Prolexic, 2013a). The DDoS attacks are usually performed from the large botnets, which are networks of remotely controlled computers. There is an increasing effort by governments and companies to shut down the botnets (Dittrich, 2012), which has lead the attackers to look for alternative DDoS attack methods. One of the techniques to which attackers are returning to is DDoS amplification attacks. Amplification attacks use intermediate devices called amplifiers in order to amplify the attacker's traffic. This work outlines an evaluation tool and evaluates an amplification attack based on the Trivial File Transfer Proto-col (TFTP). This attack could have amplification factor of approximately 60, which rates highly alongside other researched amplification attacks. This could be a substantial issue globally, due to the fact this protocol is used in approximately 599,600 publicly open TFTP servers. Mitigation methods to this threat have also been consid-ered and a variety of countermeasures are proposed. Effects of this attack on both amplifier and target were analysed based on the proposed metrics. While it has been reported that the breaching of TFTP would be possible (Schultz, 2013), this paper provides a complete methodology for the setup of the attack, and its verification.

Independent Chronicle Vol. XLVI No. 3477- August 8, 1814

A semi-weekly paper that was published from 1801 to 1817. It was previously called the Independent chronicle and the universal advertiser, and was later the Independent chronicle and Boston patriot (Semiweekly). Publishers were Abijah Adams and Ebenezer Rhoades. Topics of interest in this issue include: Page 1: notice from the U.S. War Department seeking proposals for the supply of rations to troops; account of the battle of Bridgewater; list of important military figures wounded in the battle; news of prisoner exchange; Americans and the British negotiate and new prisoner exchange convention; Page 2: report of more British troops sailing to North America; report of some Indian tribes signing a treaty to fight against the British; report of battle near Detroit; report of militia moving from Fredricksburg, Virginia to Baltimore, Maryland; report of troop numbers and casualties in the battle of Bridgewater; report that Commodore Chauncey has recovered from his illness; news of American Naval forces sailing from Sackett's Harbor; Indian tribes sign peace treaty with U.S.; news of U.S. relations with Indians in the southern U.S.; account of battle of Bridgewater and list of casualties; report of the number of men killed and wounded on both sides in the battle of Chippewa; Page 3: report of surprise attack on the British; news of warship movements in and out of Halifax; frigate Java launched in Baltimore; news of British ship movements; 3 companies of Massachusetts militia arrive at Fort Warren; news of ship movements in and out of the Port of Boston; various Marshal's notices alleging U.S. ships supplying goods to the British;

Letter written by Mahlon Taylor to Samuel Clarke commenting on US troops during Fort George occupation, July 26, 1813

Fort George, situated on the west side of the Niagara River in Niagara-on-the-Lake, served as the headquarters for the Centre Division of the British Army during the War of 1812. On May 25, 1813, the Americans launched an artillery attack on the Fort, destroying most of the buildings. Two days later, the Americans invaded the Town of Niagara and occupied Fort George. They remained in the Fort for almost seven months, but suffered defeats at the Battle of Stoney Creek and Beaver Dams. Only a small number of militia remained stationed at the Fort. Fearing an attack by the British, the Americans retreated back across the Niagara River in December, 1813. The Fort remained in British possession for the rest of the War.

La perception de l’ennemi japonais dans les médias écrits américains pendant la Deuxième Guerre mondiale

Ce mémoire offre un résumé de l’état de la recherche quant à la perception des Japonais et de l’ennemi japonais aux États-Unis avant et pendant la Deuxième Guerre mondiale. Il en ressort que la question plus spécifique du traitement réservé à l’ennemi japonais et à la responsabilité des actions de guerre perpétrées par celui-ci dans les journaux américains mérite d’être approfondie. L’analyse des articles publiés dans les trois mois suivant l’attaque japonaise de Pearl Harbour et précédant la fin officielle de la guerre dans trois grands périodiques américains de l’époque suggère que ceux-ci offrirent un traitement de l’ennemi japonais similaire à celui présent dans l’ensemble des autres média américains de l’époque, mais que ce traitement est généralement plus nuancé et éclaté dans les trois mois précédant la fin de la guerre. Certaines dissensions importantes peuvent y être constatée quant à la question de la responsabilité des actions de guerre japonaises entre les périodiques, ce qui suggère l’existence de points de vue, de valeurs et de perceptions différentes des Japonais aux États-Unis pendant la Deuxième Guerre mondiale.

Studies on sphaeroma terebrans bate of the port of Cochi

Sphaeroma terebrans Bate, one of the most destructive wood-boring isopod crustacean occurring in the Cochin harbour region was taken up for investigations on its habitat, breeding, attack on timber, salinity tolerance and respiration. The respiration of the animal under different stresses was noted using an instrument fabricated in the laboratory. Of the various hydrographic conditions of the Cochin harbour region studied, salinity is found to be the most fluctuating factor and the variations are largely influenced by the seasonal rain fall from one side and the tidal currents on the other.In spite of the great fluctuations in salinity, Sphaeroma terebrans occurs throughout the year in the Cochin harbour region, though their number varies in different months. Exposure tests show that Sphaeroma terebrans can remain for about 20 to 24 hours outside water in a damp atmosphere.

The impact of 9/11 on US REIT returns: fundamental or financial?

Following the attack on the World Trade Center on 9/11 volatility of daily returns of the US stock market rose sharply. This increase in volatility may reflect fundamental changes in the economic determinants of prices such as expected earnings, interest rates, real growth and inflation. Alternatively, the increase in volatility may simply reflect the effects of increased uncertainty in the financial markets. This study therefore sets out to determine if the effects of the attack on the World Trade Center on 9/11 had a fundamental or purely financial impact on US real estate returns. In order to do this we compare pre- and post-9/11 crisis returns for a number of US REIT indexes using an approach suggested by French and Roll (1986), as extended by Tuluca et al (2003). In general we find no evidence that the effects of 9/11 had a fundamental effect on REIT returns. In other words, we find that the effect of the attack on the World Trade Center on 9/11 had only a financial effect on REIT returns and therefore was transitory.

Speculative attacks on debts and optimum currency area: a welfare analysis

Traditionally the issue of an optimum currency area is based on the theoretical underpinnings developed in the 1960s by McKinnon [13], Kenen [12] and mainly Mundell [14], who is concerned with the benefits of lowering transaction costs vis-à- vis adjustments to asymmetrical shocks. Recently, this theme has been reappraised with new aspects included in the analysis, such as: incomplete markets, credibility of monetary policy and seigniorage, among others. For instance, Neumeyer [15] develops a general equilibrium model with incomplete asset markets and shows that a monetary union is desirable when the welfare gains of eliminating the exchange rate volatility are greater than the cost of reducing the number of currencies to hedge against risks. In this paper, we also resort to a general equilibrium model to evaluate financial aspects of an optimum currency area. Our focus is to appraise the welfare of a country heavily dependent on foreign capital that may suffer a speculative attack on its public debt. The welfare analysis uses as reference the self-fulfilling debt crisis model of Cole and Kehoe ([6], [7] and [8]), which is employed here to represent dollarization. Under this regime, the national government has no control over its monetary policy, the total public debt is denominated in dollars and it is in the hands of international bankers. To describe a country that is a member of a currency union, we modify the original Cole-Kehoe model by including public debt denominated in common currency, only purchased by national consumers. According to this rule, the member countries regain some influence over the monetary policy decision, which is, however, dependent on majority voting. We show that for specific levels of dollar debt, to create inflation tax on common-currency debt in order to avoid an external default is more desirable than to suspend its payment, which is the only choice available for a dollarized economy when foreign creditors decide not to renew their loans.

Essays on international finance, default and inflation

This thesis is composed by three papers, each one of them corresponding to one chapter. The first and the second chapters are essays on international finance appraising default and inflation as equilibrium outcomes for crisis time, in particular, for confidence crisis time that leads to speculative attack on the external public debt issued by emerging economies. With this background in mind, welfare effects from adopting common currency (chapter 1) and welfare effects from increasing the degree of economic openness (chapter 2) are analyzed in numerical exercises, based on DSGE framework. Cross-countries results obtained are then presented to be compared with empirical evidence and to help on understanding past policy decisions. Some policy prescriptions are also suggested. In the third chapter we look to the inflation targeting regime applied to emerging economies that are subject to adverse shocks, like the external debt crisis presented in the previous chapters. Based on a more theoretical approach, we appraise how pre commitment framework should be used to coordinate expectations when policymaker announcement has no full credibility and self fulfilling inflation may be possible.

Do police reduce crime? Estimates using the allocation of police forces after a terrorist attack

An important challenge in the crime literature is to isolate causal effects of police on crime. Following a terrorist attack on the main Jewish center in the city of Buenos Aires, Argentina, in July 1994, all Jewish institutions (including schools, synagogues, and clubs) were given 24-hour police protection. Thus, this hideous event induced a geographical allocation of police forces that can be presumed to be exogenous in a crime regression. Using data on the location of car thefts before and after the terrorist attack, we find a large deterrent effect of observable police presence on crime. The effect is local, with little or no appreciable impact outside the narrow area in which the police are deployed.

Spittlebug impacts on sugarcane quality and ethanol production

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Coati (Nasua nasua) Attacks on Humans: Case Report

Coatis [including Nasua nasua, the ring-tailed coati], are medium-sized mammals widely distributed in the Americas. They are social animals, whose normal diet includes insects, fruits, and small vertebrates, and rarely prey on larger sized animals. There are, to our knowledge, no reports in the medical literature of attacks on humans. This report describes a coati attack on 2 children in their home. The children sustained deep scratches and bites. The animal may have injured the humans in a defensive strike, but motivation for attack was uncertain. Coati attacks may occur in places where there is interaction between these mammals and humans.