Re-visiting the One-Time Pad

In 1949, Shannon proved the perfect secrecy of the Vernam cryptographic system,also popularly known as the One-Time Pad (OTP). Since then, it has been believed that the perfectly random and uncompressible OTP which is transmitted needs to have a length equal to the message length for this result to be true. In this paper, we prove that the length of the transmitted OTP which actually contains useful information need not be compromised and could be less than the message length without sacrificing perfect secrecy. We also provide a new interpretation for the OTP encryption by treating the message bits as making True/False statements about the pad, which we define as a private-object. We introduce the paradigm of private-object cryptography where messages are transmitted by verifying statements about a secret-object. We conclude by suggesting the use of Formal Axiomatic Systems for investing N bits of secret.Comment: 13 pages, 3 figures, submitted for publication to IndoCrypt 2005 conferenc

Groundwater markets and water use efficiency: The case of Karnataka

This study, based on primary data collected from 120 groundwater users in eastern dry zone of Karnataka compares the water use efficiency among different categories of water users, viz. well owners who do not sell water, well owners who sell water either for agricultural or non-agricultural use and water buyers (both agricultural and nonagricultural). Some of the important findings are- • The cropping pattern varies between categories, with both the sellers and buyers preferring low water intensive mulberry crop, while the self user's category grew more water intensive crops. • Farmers who sold water for non-agricultural purposes earned the highest return (because of higher end-use price) and also made the most efficient use of water. Thus, making a point that end-use pricing is a key in shaping marginal productivity of water. • Compared to the self-users, farmers selling water for either agricultural or non-agricultural purposes realized higher marginal productivity. Thus,groundwater markets acted as an effective tool in enhancing efficient use of a scarce resource.This study explores efficiency and equity in groundwater markets in the hard rock areas of Karnataka. It compares the water use efficiency of farmers using groundwater for irrigating their land and also selling it for agricultural purpose (WSA, n=30), farmers using water for irrigating their land and also selling for non-agriculture purpose (WSNA, n=15), farmers who do not either sell or buy water but use it on their farms (WO, n=30), farmers who are buying groundwater for agriculture purpose (WBA, n=30), and buyers of water for non-agriculture purpose (WBNA, n=15). The Nash equilibrium framework describing the bargaining power of buyers and sellers of groundwater is used. Sidlaghatta taluk in eastern dry agroclimatic zone (EDZ) of Karnataka is chosen because it supports intensive groundwater markets. The objective of the study is to find out water use efficiencies among different groups of water users with the hypothesis that WSNA obtain higher water use efficiency than WSA, WBA, and WO.Groundwater markets, efficiency, equity, Resource /Energy Economics and Policy,

Impact of water harvesting on groundwater recharge, productivity and net returns with integrated farming systems approach in eastern dry zone of Karnataka

The paper evaluates the performance of water harvesting structures by looking at the case of the Sujala watershed in Karnataka. The water harvesting structures have facilitated the rejuvenation of failed wells and enhanced the water yield. About 75% of the failed bore wells were rejuvenated as against 66% in the non- watershed. The yield of bore wells were increased by 21% in the watershed where as in non-watershed area the water yield has reduced by 11%. Investment analysis of water harvesting structures indicated that for every rupee of present investment on water harvesting structure there is a return of Rs. 2.79 in farm pond and Rs. 2.19 in recharge pits. Further, productivity of crops has enhanced through protective irrigation given at critical stages of crop growth and moisture conservation, which in turn increased the net returns of the farmer.Length: pp.764-774Water harvestingGroundwater rechargeWatershedsDevelopment projectsCostsFarming systemsArid zonesWellsIrrigation waterCase studies

Groundwater markets and water use efficiency: The case of Karnataka

Research highlight based on a paper titled “Groundwater markets promoting efficiency in water use in agriculture in Karnataka.”Water market, Groundwater extraction, Water use efficiency, Wells, Crop production, Irrigation water, Domestic water, Pricing, Models, Policy, India, Karnataka, Demand and Price Analysis, Environmental Economics and Policy, Food Security and Poverty, Productivity Analysis,

Economic analysis of groundwater markets in central dry zone of Karnataka

Water market, Groundwater irrigation, Water use efficiency, Economic analysis, India, Karnataka, Agribusiness, Agricultural Finance, Crop Production/Industries, Environmental Economics and Policy, Production Economics, Productivity Analysis,

Economic Analysis of Groundwater Markets in Central Dry Zone of Karnataka

Groundwater, unlike surface water, is expensive and relatively scarce and hence should be used to grow crops that are responsive to protective irrigation, require less water and are remunerative. Sellers and buyers of groundwater have put large areas under paddy, a water-intensive crop. This needs to be disciplined through effective groundwater institutions. Groundwater literacy has to be promoted by educating farmers on the pros and cons of overexploitation. For farmers who do not own wells, one way to enable access to water is through group investments in well irrigation. This would require provision for institutional credit for such groups and energization of pumpsets. This will provide an environment of sharing available groundwater and the associated costs. The functioning of groundwater markets in hard rock areas of the semi arid dry zone of Karnataka show two types of arrangements. In the first one, irrigation services are provided on demand and water charge is levied on hourly basis. In the second one, irrigation services are provided for the whole crop season, and cash equivalent of a fixed share of crop produce is paid as water charge. For water buyers, crop sharing arrangement yielded higher returns than that under hourly rates. Comparative analysis of allocative efficiencies of input use for sellers and buyers in groundwater markets show that water buyers obtain higher economic efficiency in water used for crop production than sellers, though both buyers and sellers are growing water-intensive crops such as paddy.water markets, Resource /Energy Economics and Policy,