Security Assumptions Research Articles

Secure key-evolving for public key cryptosystems based on the discrete logarithm problem

This paper addresses the security and efficiency of key-evolving protocols in public key encryption and signature schemes, where the security assumption is the intractability of the discrete logarithm problem. We identify the key-independence property as the security goal of key-evolving, so that each periodic secret key is independent of each other. The first protocol operates in Z(superscript * subscript p) and is efficient for the secret-key holder, the second operates in Z(superscript * subscript n) and is efficient for the public-key holder For both protocols, we provide proofs and analysis for correctness, security and efficiency

Improved authenticated multiple-key agreement protocol without using conventional one-way function

An authenticated multiple-key agreement protocol enables two entities to authenticate each other and establish multiple common keys in a two-pass interaction, and a protocol without using a conventional hash function simplifies its security assumption on only public hard problem. In 2001, Yen et al. proposed an improved multiple-key agreement protocol to overcome the attacks that break the previous variants. However, the authors show that an impersonator can easily forge message without being detected, and can establish common session keys with the communicating party. To overcome all the weakness, we propose an improved scheme that also achieves better key utilization, compared to the previous variants.

Convertible Authenticated Encryption Scheme Without Using Conventional One‐Way Function

An authenticated encryption allows the designated recipient to verify the authenticity while recovering the message. To protect the recipient's benefit in case of a later dispute, a convertible authenticated encryption scheme allows the recipient to convert the authenticated encryption into an ordinary signature so that it becomes a publicly verifiable. This paper shows a universal forgery attack on Araki et al.'s convertible authenticated encryption scheme, and proposes a new convertible authenticated encryption scheme. Without using any conventional one-way function, the proposed scheme simplifies its security assumption on only a public hard problem - the discrete logarithm problem.

Navies and world events in the 21st century

As the number and diversity of conflicts at different levels has increased in recent years, and the nature of threats has become more dangerous, the need for effective naval forces to meet and counter those threats and situations will grow. But no one nation will be able to ‘go it alone’ in our increasingly interdependent world. Within this basic security assumption, however, John Dalton, US Secretary of the Navy, detects a paradox: the perceived lack of an obvious, well‐defined threat led to substantial reduction in the navies and militaries that ostensibly triumphed in the Cold War. Since then, the US navy for one has been busier than ever in undertaking actions and exercises with allies in many different contingencies around the world What has been seen to matter more is the quality and capability of naval forces, rather than quantity. In focusing on the roles of naval forces into the 21st century, and outlining scenarios in which those forces may need to be’ used, Secretary Dalton also highlights the need for targeted investment in key technologies and the recognition that enhancing collective security entails a different kind of cost involving national sovereignty on security issues. He concludes that combined naval operations under the aegis of international organisations play a large part in enhancing national sovereignty and can, through close cooperation, help to define international political will to maintain global security.

On the (Im)possibility of Basing Oblivious Transfer and Bit Commitment on Weakened Security Assumptions

We consider the problem of basing Oblivious Transfer (OT)<br />and Bit Commitment (BC), with information theoretic security, on seemingly weaker primitives.We introduce a general model for describing such primitives, called Weak Generic Transfer (WGT). This model includes as important special cases Weak Oblivious Transfer (WOT), where both<br />the sender and receiver may learn too much about the other party's input, and a new, more realistic model of noisy channels, called unfair noisy channels. An unfair noisy channel has a known range of possible noise levels; protocols must work for any level within this range against adversaries who know the actual noise level. We give a precise characterization for when one can base OT on WOT. When the deviation of the WOT from the ideal is above a certain threshold, we show that no information-theoretic reductions from OT (even against passive adversaries) and BC exist; when the deviation is below this threshold, we give a reduction from OT (and hence BC) that is information-theoretically secure against active adversaries.<br />For unfair noisy channels we show a similar threshold phenomenon for bit commitment. If the upper bound on the noise is above a threshold (given as function of the lower bound) then no information-theoretic reduction from OT (even against passive adversaries) or BC exist; when it is below this threshold we give a reduction from BC. As a partial result, we give<br />a reduction from OT to UNC for smaller noise intervals.

From International Institutionalism to Revolutionary Expansionism: The Foreign Policy Discourse of Contemporary Russia

The purpose of this essay review is to explore the foreign policy discourse in contemporary Russia. The argument is made that Russian foreign policy is still open to the influence of ideas across the political spectrum and that examining the discourse extant in the society is useful in revealing the country's competing schools of thought. Four schools of thought are identified that have different definitions of security and different policy goals. After defining the four schools' security assumptions, attention is directed toward analyzing the images each has of Russia as an international actor and about Russia's international environment. The essay concludes with a consideration of the grand strategies that follow from each school’s proposals and offers a preliminary assessment of the possible evolution of Russian foreign policy drawing on the relative status of each school.

Can we redefine national security in time?

Recent changes in the international situation, particularly the end of the Cold War, are focusing attention on the need to redefine national security to take into account growing threats from a variety of global problems. We should be asking what are the real threats to our security and examining our military and security assumptions. Strategies beyond military readiness should be evolved to prevent and deter conflicts. All countries should have a debate about national security. National security should be redefined in broader terms than the defense of borders. It should provide conditions for the health, education, and well-being of society and for a sustainable economy. The debate needs, however, reliable facts and statistics about how well these conditions have been created around the world. Fortunately, two annual publications contain the information needed for an informed debate on national security issues. They are World Militaly and Social Expenditures 1996, published by World Priorities Inc., Washington, DC, and the SIPRI Yearbook 1996: Armaments, Disarmament and International Security, published by the Stockholm International Peace Research Institute. The picture emerging from the wealth of statistics--on world military expenditures, global and regional conflicts, military research and development, and global arms production and trade-contained in these volumes is, generally speaking, a bleak one. It becomes clear that the most serious global problems arise from the rapidly growing world population and the widening gap between rich and poor

Improved digital signature suitable for batch verification

In this paper, an improved digital signature is developed based on the famous Schnorr (1990) or Brickell-McCurley (1991) schemes. It is shown that both the new scheme and the previous two originals rely on the same security assumptions. The novel feature of this proposed signature is that it can be verified in a batch manner and the improved efficiency is approximately proportional to the number of signatures to be verified. >

Quality of attachment and home environments in children prenatally exposed to PCP and cocaine

AbstractQuality of attachment, disorganization in attachment, and the contribution of caregiver interactions in the home were investigated for infants prenatally exposed to PCP and cocaine and their caregivers. The drug-exposed infants were compared with infants of similar ethnicity, socioeconomic status (SES), and living in the same geographical area of the city with non-substance-abusing mothers. The majority of drug-exposed infants were insecurely attached to their caregivers and did not differ in the percentage of security in the three caregiving environments in which the infants were growing up: biologic mother care, kinship care, or foster mother care. The majority of drug-exposed children were disorganized. Change in caregivers during the first year was not found to be related to the rate of insecurity in any of the caregiving environments. The majority of the non-drug-exposed comparison infants were securely attached, and only a small percentage were disorganized. The high incidence of insecurity in the drug-exposed group is discussed in relation to maternal and environmental circumstances that can alter the assumption of security in attachment for the majority of children and caregivers toward insecurity in attachment.

Deposit Ceilings and Monetary Policy

SINCE 1966, the Federal Reserve Board has experimented with the use of Regulation Q, the regulation which specifies the maximum interest rates banks are permitted to pay on time and savings deposits, as an active tool of monetary policy. Since September 1966, the Federal Home Loan Bank Board has been empowered to impose ceilings, on savings and loan associations and some mutual savings banks movements in these ceilings to be coordinated with movements in Regulation Q ceilings. In spite of our now-substantial experience with these ceilings, there appears to be no consensus on what purely macro-economic consequences emerge from the employment of deposit ceilings. We need answers to the following two questions: 1) Does the existence of effective deposit ceilings strengthen or weaken standard monetary policy actions? 2) Can the manipulation of deposit ceilings serve as an independent active tool of stabilization policy and, if so, what is the direction of its impact? 1 The official view of the Federal Reserve Board on question (2) appears to be that effective deposit ceilings (attention is typically focused on Q ceilings) are depressive while relaxation of those ceilings is expansionary.2 We know of no clear statement of their position on question (1). There is scant discussion of these issues in the professional literature. In the most general theoretical discussion of deposit ceilings, Tobin (1970) suggests (relying on some casual empirical evidence) that the sign of response of the level of economic activity to changes in interest rate ceilings may vary depending on whether an interest rate variable or a reserve variable is exogenous. He apparently believes that the response we are interested in (letting reserves be held constant) is typically inverse a rise in interest rate ceilings being restrictive. He does not consider question (1). Using a much more restrictive model, Warren Smith (1967) has argued that monetary policy is stronger with effective ceilings (only Q ceilings are considered) than without them. He does not consider question (2). We deal with both questions in this paper. Our analysis suggests that the Tobin and Smith conclusions (on questions (2) and (1), respectively) are incompatible. The model we employ in dealing with these questions differs from both the Smith and Tobin models.3 Our model builds on theirs by incorporating two intermediary claims (both commercial bank time deposits and nonbank intermediary claims), by including currency demand functions, and by considering the impact of incorporation of the price level in the model. Unlike Tobin, we employ the commonplace macro-economic assumption of a single marketable security.4