Key Recovery Mechanism Research Articles

Parasitic overview on different key management schemes for protection of Patients Health Records

The main goal of HIPAA (Health Insurance Portability and Accountability Act) is to protect health information of individuals against access without consent or authorization. Security and privacy are the main issues in HIPAA. A compliant key management solution is used to reduce harm and risk while providing cryptographic mechanisms. Using ECC (Elliptic Curve Cryptography) we ensure more security for access of patient’s health records. This provides same level of security for access of patient’s health records. Patient’s health Information is stored in RFID cards. Finally, the proposed method ensures higher level of security than other existing cryptographic techniques. ECC provides more security even with small key sizes. Proposed scheme describes the various counter measures for improving security and a key recovery mechanism for the protection of keys.

Augmenting security for electronic patient health record (ePHR) monitoring system using cryptographic key management schemes

Security plays a major role in most of the fields including pharmaceutical field. Authorization and Authentication are the key concepts in supporting notable areas of the cyber-health world. HIPAA's (Health Insurance Portability and Accountability Act) ultimate focus is to preserve the privacy of the health records of an individual without disclosing it and preventing the data from unauthorized access. A complaint key management solution is applied over the patient's health records to reduce the risk factor while engaging with cryptographic mechanisms. Though there are many existing cryptographic algorithms such as Elliptic curve cryptography, Elgammal's key exchange algorithm which provides security to the access of patient's health records, the proposed key management solution will overlay the same variant of security to the Electronic Health Records (EHR). This paper provides the countermeasures for improving security and suggests a key recovery mechanism for the protection of keys used in the security mechanism.

Analysis of non-equilibrium foamy oil flow in cyclic solvent injection processes

Non-equilibrium phase behavior (i.e., solvent dissolution/exsolution) and solvent transport are key recovery mechanisms in many non-thermal post-CHOPS (Cold Heavy Oil Production with Sand) processes, such as cyclic solvent injection (CSI), in western Canada and Venezuela. Foamy oil refers to the non-equilibrium phenomenon where gas bubbles are dispersed in the oil phase during exsolution, resulting in a decrease in oil viscosity. This is a well-recognized behavior in heavy oil primary production (CHOPS) and has implications in recovery during CSI. In this paper, a mechanistic simulation model is constructed based on a set of pressure depletion experiments, and the calibrated model is used to analyze the effects of solvent compositions and operating schedules on recovery efficiency.First, a series of pressure depletion tests are conducted using both bulk fluid systems and porous media to examine the non-equilibrium release of solvent (CO2, CH4 and C3H8) from saturated live oil during the production cycles of CSI. The non-equilibrium live oil viscosity profile is inferred from calibrated NMR measurements. Different combinations of solvent mixtures and pressure depletion rates are tested to examine their impacts of gas exsolution. Next, a detailed mechanistic simulation model is constructed and calibrated against a set of experimental measurements. A fluid model is defined based on equilibrium saturation pressures and gas-oil ratios corresponding to different combinations of solvent and dead oil. A viscosity model is formulated using measurements at different temperatures and solvent-oil mixtures. Reaction kinetics is implemented to represent the non-equilibrium exsolution of gas from solution gas to bubble gas and free gas in foamy oil flow.The simulation model shows the response of viscosity and oil production as a function of pressure for a porous medium saturated with live oil in a single depletion cycle. The model predicts a delay in free gas formation in the sand pack, as observed in the experimental program. Propane-based and carbon dioxide-based solvent mixtures exhibit significant foamy oil characteristics, enabling the oil viscosity to remain close to its live oil value even with pressures that are much lower than saturation pressure. The rates of gas exsolution and oil production are strongly dependent on the pressure depletion schedule, as well as the solvent compositions and properties.Although a number of models were developed in the past to describe the dissolution of solvent and bubble formation, calibration of these models against actual observations remain challenging. The model developed in this study is calibrated and corroborated by detailed experimental observations; hence, it can be further scaled up to study recovery performance at the pilot or field scales. Many existing solvent technologies suffer from low production rates due to limited solvent/heavy oil interaction. Improving our understanding of solvent dissolution/exsolution under different pressure conditions would aid in the design of operating strategies (e.g., pressure depletion and solvent injection schemes) for enhanced solvent/oil mixing and transport.

Coupling Microfluidics Data with Core Flooding Experiments to Understand Sulfonated/Polymer Water Injection.

The injection of sulfonated-modified water could be an attractive application as it results in the formation of a mechanically rigid oil-water interface, and hence, possible higher oil recovery in combination with polymer. Therefore, detailed experimental investigation and fluid-flow analysis into porous media are required to understand the possible recovery mechanisms taking place. This paper evaluates the potential influence of low-salt/sulfate-modified water injection in oil recovery using a cross-analyzed approach of coupled microfluidics data and core flooding experiments. Fluid characterization was achieved by detailed rheological characterization focusing on steady shear and in-situ viscosity. Moreover, single and two-phase micromodels and core floods experiments helped to define the behavior of different fluids. Overall, coupling microfluidics, with core flooding experiments, confirmed that fluid-fluid interfacial interaction and wettability alteration are both the key recovery mechanisms for modified-water/low-salt. Finally, a combination of sulfate-modified/low-salinity water, with polymer flood can lead to ~6% extra oil, compared to the combination of polymer flood with synthetic seawater (SSW). The results present an excellent way to make use of micromodels and core experiments as a supporting tool for EOR processes evaluations, assessing fluid-fluid and rock-fluid interactions.

Strong pinning of triple junction migration for robust high strain nanostructures

ABSTRACTThe universality of a key recovery mechanism: triple junction migration in high strain nanostructures is revealed herein. This migration is the only means to uniformly coarsen deformed lamellar microstructures. Migration of medium to high angle geometrically necessary boundaries at triple junctions is resisted by strong pinning phenomena. Pinning by low angle dislocation boundaries is the novel mechanism that greatly adds to the solute drag of these higher angle boundaries during migration at triple junctions. Solutes furthermore cause a significant increase in the dislocation density of the low angle boundaries formed during deformation and thus greatly enhance the observed pinning. Boundary pinning by dislocation boundaries and solute drag is analysed for deformed Ni of different purities via in and ex situ electron microscopy. A kinetic model is utilised to obtain activation energies that quantitatively demonstrate the strength of this pinning. A new strategy for achieving robust nanostructured metals is developed based on solute and dislocation pinning of triple junction migration – a universal recovery mechanism in deformed lamellar microstructures.

Scaleup of Effective Mass Transfer in Vapour-Extraction Process Accounting for Field-Scale Reservoir Heterogeneities

Summary Vapour extraction (VAPEX) is a nonthermal process using vapourized solvents, with promising potential to reduce steam consumption in heavy-oil recovery. The key recovery mechanisms are convection and molecular diffusion enhanced by various spreading mechanisms [e.g., capillarity and velocity variations at the micro and macroscale (i.e., dispersion and mixing)]. The efficiency of diffusion/dispersion depends significantly on reservoir heterogeneities, which exhibit a wide range of length scales. This paper demonstrates a procedure for quantifying the scaling characteristics of effective mass transfer accounting for heterogeneities based on the volume-averaging approach. Volume averaging is a mathematical technique used to derive continuum equations at coarse scales given representative transport equations at fine scales. Although treatment of transport problems has been published in the past, application to stochastic geological systems is limited. In the proposed procedure, results from a fine-scale numerical flow simulation reflecting the full physics of VAPEX over a small element of the reservoir are integrated by use of the volume-averaging technique to provide effective description of mass transfer at the coarse scale. Scaling characteristics of effective mass transfer are investigated systematically for different heterogeneity distributions. Results show (1) spatial variability of effective-mass-transfer coefficients increases as a solvent chamber advances through the reservoir; (2) mean and variance of effective-mass transfer vary with length scale in a fashion similar to that of recovery statistics; and (3) variability in effective-mass transfer is a strong nonlinear function of heterogeneity. An original contribution is to provide a general framework for developing scaling relationships of effective mass transfer in VAPEX accounting for reservoir heterogeneities. It also presents an important potential in modelling of other solvent-injection applications. Results demonstrate that effective-mass transfer varies with length scale and heterogeneity; hence, it should be represented properly for accurate prediction of recovery performance in simulations using scaled-up reservoir models.

IKEv2를 지원하는 IPSec 에서의 키 복구 설계

본 IPSec은 인터넷의 네트워크 계층에서 IP 메시지에 대하여, 암호화 서비스와 인증 서비스를 제공하는 보안 프로토콜이다. 본 논문은 모바일 환경에서 요구되어지는 IPSec 에서의 키 복구를 위하여 IKEv2에 적용할 수 있는 키 복구 수행 메커니즘을 제시한다. 이는 IPSec과 IKEv2에서 호환성을 유지할 수 있으며, 기존의 메커니즘보다 안전하며, 네트워크 오버헤드를 줄일 수 있으며, 키 위탁기관이나 권위기관에 종속되지 않고 키 복구 결정을 할 수 있는 메커니즘이다. IPSec is the security protocol that do encryption and authentication service to IP messages on network layer of the internet. This paper presents the key recovery mechanism that is applied to IKEv2 of IPSec for mobile communication environments. It results to have compatibility with IPSec and IKEv2, reduce network overhead, and perform key recovery without depending on key escrew agencies or authorized party.

Providing key recovery capability for mobile communications

AbstractIn this paper, we propose a novel security scheme with key recovery capability for mobile communications. The proposed key recovery mechanism offers a “backdoor” for an authorized agency to monitor suspected communications while protecting legal users from unauthorized disclosure of their data privacy. All the features form a unitary security scheme with monitoring service. The performance analysis shows that our scheme has a low‐computational complexity and it can be practically deployed on contemporary mobile devices. Copyright © 2009 John Wiley & Sons, Ltd.

Simulation of counter-current imbibition in water-wet fractured reservoirs

Counter-current imbibition, where water spontaneously enters a water-wet rock while oil escapes by flowing in the opposite direction is a key recovery mechanism in fractured reservoirs. Fine grid, one- and two-dimensional simulations of counter-current imbibition are performed and the results are compared with experimental measurements in the literature. The experimental data are reproduced using two sets of relative permeabilities and capillary pressures. One set is derived from a counter-current experiment and one set is computed using pore-scale modelling. Two-dimensional simulations of water flow through a single high permeability fracture in contact with a lower permeability matrix are run. The results are compared with experimental measurements of fracture flow and matrix imbibition in the literature and with one-dimensional simulations that account for imbibition from fracture to matrix using an empirical transfer function. It is shown that with this transfer function the behavior of the two-dimensional displacement can be predicted using a one-dimensional model.

Matching key recovery mechanisms to business requirements

This paper addresses the business needs for key recovery as a countermeasure to the threat of losing potentially valuable information. Several requirements essential for a sound key recovery mechanism are described, and the applicability of two main classes of existing key recovery schemes to a corporate environment is examined. Different requirements are identified for key recovery mechanisms for communicated and archived data, and a further study is made of the applicability of existing mechanisms to these two cases.

A group key recovery mechanism based on logical key hierarchy

Secret group communication can be achieved by encryption messages with a group key. Dynamic groups face the problem of changing the group key whenever members join or leave. One of the solutions to this problem is to send updated group keys to members via rekey messages in a secure manner. The recovery of lost group keys consequently becomes important because a member cannot decrypt the group data if she loses the rekey messages. Also, any rekey messages lost while a member is logged off cannot be recovered in real-time. Saving recent rekey messages and resending them by the key distribution center not only requires large storage space, but also can cause unnecessary transmission and decryption of keys. Furthermore, the keys in the unsaved rekey messages cannot be recovered. This paper analyzes the problem of rekey message loss and proposes an efficient scheme for recovering group keys based on a logical key hierarchy. The group key generation method used in the scheme make it possible to recover group keys without transmission and decryption of useless keys.

A group key recovery mechanism based on logical key hierarchy

Secret group communication can be achieved by encryption messages with a group key. Dynamic groups face the problem of changing the group key whenever members join or leave. One of the solutions to...

A Common Key Recovery Block Format: Promoting Interoperability Between Dissimilar Key Recovery Mechanisms

When cryptographic products that employ different key recovery mechanisms need to interoperate with one another, one of the major obstacles is the inability of the decryptor product to recognize, and optionally validate, the key recovery information generated by the encryptor product. In this paper, a common Key Recovery Block (KRB) format is being proposed to facilitate interoperability between heterogeneous key recovery systems. The KRB serves as a container for mechanism-specific key recovery information, and supports techniques to identify and optionally validate the contained key recovery information. This specification provides an extensible set of KRB validation techniques - however, it makes no attempt to set a preference for one technique over the others. The choice of validation technique(s) used is determined by the policies (with respect to the use of cryptography and key recovery) that apply to the encryptor and decryptor products. It may be noted that the KRB format specification is independent of the encryption algorithm used to protect the confidentiality of the data, and independent of the communication or storage protocol used to carry the encrypted data. It should also be recognized that the KRB format proposed in this paper is of limited scope. It assumes that the key recovery information can be made available to interested parties along with the encrypted data. There are a number of open issues regarding the techniques that allow key recovery information to be associated with encrypted data (whether the key recovery information and the encrypted data are transmitted over the same channel or separate channels) — these issues are beyond the scope of this proposal.

Flow Regimes During Cyclic Steam Stimulation At Cold Lake

Abstract From the analyses of production data from thousands of cyclic steam stimulation (CSS) cycles at Cold Lake, a conceptual model of the flow regimes has been developed. It indicates that the traditional reservoir flow conceptualization of bitumen and water slipping past each other according to the relative permeability curves is, to a large extent, inapplicable at Cold Lake, and very likely inappropriate to visualizing steam stimulation in general. Upon completion of steam injection, three distinct and sequential flow regimes characterize the production phase: type I, free water with little if any bitumen production: type II, slugs of free water alternating with slugs of water in bitumen emulsion, resulting in scattered production rates; and type III, a single phase flow condition comprising of water in bitumen emulsion with very smooth, slowly varying production rates. In early cycles the majority of the bitumen production occurs during type III flow, with the type II regime being small. Over time, as the cycle number increases, the water content of the emulsion in type III flow reaches a maximum of about 50%; the flow then increasingly remains in type II condition, corresponding to a decline in the well's OSR and increase III the wafer/oil ratio (WOR) as the well begins to approach its economic limit. The swelling of the bitumen by the entrained water permits the emulsion to occupy essentially the whole pore space during type III flow, incorporating an otherwise continuous free water that could compete for production at the wellbore. This may be the physical reason for the need to introduce hysteresis to depress the water relative permeability during numerical stimulations of the production phase of CSS. Introduction Using cyclic steam stimulation (CSS), Esso Resources Canada Limited produces in excess of 14,000 m3/day of 10 API gravity bitumen from the Clearwater formation at Cold Lake, Alberta(l). A significant technological effort supports this large commercial thermal recovery project. Progress has been made in delineating the relative importance of key recovery mechanisms of CSS, such as formation recompaction, solution gas drive and gravity drainage(2). This paper reports the reservoir flow regimes during the production phase of CSS deduced from the analyses of production data from thousands of cycles. This analysis leads to the view-point that the traditional reservoir flow conceptualization of bitumen and water slipping past each other according to the relative permeability curves is, to a large extent, inapplicable at Cold Lake, and very likely inappropriate to visualizing steam stimulation in general. Perusal of the production data shows that the water and bitumen production rates often track each other with considerable coherence; this is most striking when the WOR is one. This is illustrated in Figure 1 for well A in its fourth cycle production. Note that in the later half of the cycle, for a period of 150 days, the WOR persists as one even during wide variations in fluid rates. During this period the reservoir is cooling, with the viscosity of the bitumen increasing much faster than that of the water; by the end of the period, it is estimated that the ratio of bitumen to water viscosity has increased at least by a factor of two.