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ISBN 978-952-5726-09-1 (Print) Proceedings of the Second International Symposium on Networking and Network Security (ISNNS ’10) Jinggangshan, P. R. China, 2-4, April. 2010, pp. 210-213 Combining Permission Based Delegation Model with Chinese Wall Chunxiao Ye 1 , Fawen Yu 1 , Tinsen Huang 1 , Haibo Hu 2 , and Hong Xiang 2 1 College of Computer Science, Chongqing University, Chongqing, China Email: yecx@cqu.edu.cn 2 School of Software Engineering, Chongqing University, Chongqing, China Email: {oram, xianghong}@cqu.edu.cn Abstract—Chinese Wall Security Policy (CWSP) is a widely applied access control policy in many fields, especially in commercial world. Delegation is one of the hot topics of access control technologies. Delegation with CWSP means delegation must satisfy not only delegation constrains but CWSP as well. There exist many delegation models, such as RBDM, RDM2000 and PBDM et al, but few focus on it. This paper proposed an approach of how to delegate permission with the restriction of CWSP. Although CWSP is part of delegation constraint, it does not mean that existing delegation models can be easy applied to this kind of delegation. In our approach, we first define two types of delegation constraints consisting of CWSP. Then we discussed different types of revocation and found that automatic revocation can make delegation safer than user revocation. Also, we found that there exists security vulnerability in multi-step delegation and gave some feasible solutions. Finally, this paper gave system implementation architecture and some examples to show how our approach works properly in a situation with CWSP. Index Terms—Permission Based Delegation Model, Delegation, Chinese Wall Security Policy, CWSP In a commercial environment, delegation occurs frequently, especially when someone is on a business trip. That means a user (delegator) can transfer her permissions to other person (delegatee) and delegatee can perform these transferred permissions just like the delegator herself. Of course, delegation is constrained by system security policy. Above researches have focus on delegation constraints, but few have elaborated delegation with CWSP. II. MOTIVATION Let us consider the example shown in figure 1: Alex can access to data of Bank A and Oil Company B, and Mike can access to data of Bank B and Oil Company A. Because Bank A and B, Oil Company A and B are in different Conflict of interest classes (COI) respectively, according to CWSP, there is a “wall” between Alex and Mike. I. INTRODUCTION Delegation means that a user (delegator) can give her permissions to other person (delegatee). There are three types of situations in which delegation can take place: backup of roles, decentralization of authority and collaboration of work. Human-to human delegation has received considerable attention recently [1] ~ [5]. RBDM [1] is the first delegation model based on role. RBDM deals with flat and hierarchical role, multi-step delegation. RDM2000 [2] is an extension of RBDM. A rule-based declarative language has been proposed to specify and enforce policies in delegation. PBDM [3] is a flexible delegation model that supports multi-step delegation and revocation in role and permission level. RPRDM [4] only addresses repeated and partial delegation. ABDM [5] is a strict and more secured delegation model both in temporary and permanent delegation. Chinese Wall Security Policy model (CWSP model) [6] was first defined by Brewer and Nash in 1989. It has been widely applied in commercial world where there exists conflict of interest among different companies. CWSP can be seen as a mixture of DAC and MAC and is seem as a history-based access control policy. Figure 1. User access to different datasets Figure 2 illustrates examples of delegation among different persons. P Bank A and P Oil Company B stand for access right to Bank A’s and Oil Company B’s datasets respectively. According to CWSP, Alex cannot choose Mike and delegate permissions to him. So, Alex can choose another person, say Tom, and perform delegation. Assume Alex delegates P Bank A to Tom, as shown in figure 2 (a). If Tom has accessed to those datasets that Mike is able to access to, the delegation will be prohibited; otherwise the delegation will succeed. In this case, because Tom has no permissions before delegation, the delegation succeeds. Let us consider another situation: assume Alex and Mike delegate some of their permissions to Tom separately, as shown in figure 2(b). According to CWSP, © 2010 ACADEMY PUBLISHER AP-PROC-CS-10CN006 210
Figure 2. Example of single-step delegation Tom can accept permissions within one COI, say Bank A and B, and once he choose to access to one bank’s dataset and a “wall” will prevent him from the other’s. So, delegator does not know whether the delegation is success after the delegation finished, for it depends on delegatee’s selection of permissions. For example, if Tom chooses to access to bank A’s data, then Alex’s delegation is success and Mike’s failed. This is a kind of “uncertain delegation” but is actually allowed according to CWSP. Thus we have two choices: to make delegation easy, we can prohibit it, or to make delegation flexible, we can allow it. The former is easy to implement and less safe and the latter is safer and makes the implementation somewhat difficult. In the former case, CWSP can be expressed by delegation constrains, such as prerequisite condition (CR) and in the later by activation constrains. If “uncertain delegation” is allowed, for the purpose of not violating CWSP, once a delegatee activates some permissions, the delegatee is prohibited from activating the corresponding conflict permissions for ever or those permissions will be revoked immediately. III. DELEGATION WITH CWSP CWSP can be regarded as a kind of SOD and looks like dynamic SOD [7]. We also believe CWSP is an object-based separation of duty as mentioned in [7], but the difference is that we use role-based separation of duty to describe CWSP. A. Concepts Here we give some concepts definitions: Definition 1 • T, U, AR, RR, TDR, P, O, OBJ and R are set of time, user, administrative role, regular role (created by system administrator), temporary delegation role (created by delegator), permission, operation, object and role respectively. t 0 , t c ∈T. t 0 is the initial time point and t c is current time point of system. • P⊆O×OBJ, R=RR∪TDR • PRA⊆R×P • URA⊆U×RR • UDA⊆U×TDR • own(u):U→2 TDR and ¬∃ (u 1 , u 2 ∈U, tdr∈TDR) ∧ (u 1 ≠u 2 ) ∧ (tdr∈own(u 1 )∧tdr∈own(u 2 )): a function mapping a user to a set of delegation roles which she created. • UA= URA∪UDA • UA ti is the UA at ti time point. • UA=U tc . • UAH=UA t0 ∪…∪UA tc : a relation of user-role assignment history. Other concepts’ definitions can be found in [3] and [5]. Definition 2 for two permissions p 1 = (o 1 , obj 1 ) and p 2 = (o 2 , obj 2 ), if obj 1 and obj 2 belong to the same COI, we call p 1 and p 2 are conflict with each other, denoted as p 1 ↔ p 2 . Definition 3 we call r and r’ are conflict with each other, if (∃ p, p’∈P)∧ (r, p) ∈PRA ∧ (r’, p’) ∈PRA ∧ p ↔ p’, denoted as r ↔ r’. A role r’s conflict roles can be denoted as Rr, where ∀r i ∈R r , r ↔ r i . Definition 4 ⎧true (u,r) ∈UAH,u hasactivated/ is activatingr, hasAct(u, r) = ⎨ ⎩false otherwise. Definition 4 defines the function to judge whether a role has been activated or being activated. B. Delegation Delegation constraint is vital for delegation security. In our work, delegation constraint consists of three parts: the first one is prerequisite role (CR), the second is SOD and the third is CWSP. Although CWSP looks like SOD, we separate it from SOD for there are two types of CWSPs: weak and strong CWSP: • Weak CWSP can be seen as a normal delegation constraint. This means a user can keep two conflict roles at the same time but she can only activate one role and lost the right of activate the other one for ever. So, if a delegatee has roles that conflict with delegation role but she has not activated or is activating these roles, delegation will be allowed. • Strong CWSP is stricter than weak CWSP. This means if delegatee already has roles that conflict with delegation role, delegation will not be allowed even those roles has not been activated before. Strong CWSP beyond the basic security restrictions of CWSP and is useful in a situation of multi-step delegation. Accordingly, to obtain different delegation security level, delegation can be defined as two different types: 211
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Proceedings The Second Internationa
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Table of Contents Message from the
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Zuming Xiao, Zhan Guo, Bin Tan, and
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Message from the Symposium Chairs T
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Second International Symposium on N
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model that can deal with time serie
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training for the Wushu competition
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information, called weak uncertain
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Student side Student side Student s
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If we define element of student as
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QoS, each frame data is divided int
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for Imaging Two and Three Phase Flo
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A. Profiling&following control algo
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Research and Realization about Conv
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support 10 Mb / s. But ENC28J60 onl
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ubber according to the mass ratio o
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Ⅲ. AN IMPROVED DNA ALGORITHM FOR
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Ⅴ.CONCLUSION REMARKS DNA computer
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its first child q 1 on the left, th
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chains can greatly improve efficien
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II. RELATED WORK A. Mobile Service
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special services. SOAP is used to b
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detection methods of DDoS attacks m
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Step4 calculate the new subordinate
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Figure 1. An analysis of the partit
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The preceding three formulas can be
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And the decay speed of buffer seque
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distance of view point. Given that
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Ⅳ. EVALUATION OF BLENDED LEARNING
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symmetric with respect to the origi
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each sample belongs to each categor
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A. Data Preparing To generate our t
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Strong earthquake 0.1< M L
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indirect causes, and the logical re
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egression. Granger causality test i
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B. Evaluation We have evaluated thi
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used as a source and neighboring ce
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Figure 3. Drainage networks generat
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under the endorsement of both the m
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TABLE I. DESCRIPTION OF PROPOSITION
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Figure 9. (a)the original image.(b)
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that studying being going to be to
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Reference[10] analyzed the evolutio
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module, communication module, apper
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After the comprehensive performance
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system testing can be seen that the
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III. AUTONOMIC RESOURCE ALLOCATION
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The QoE i (T i ) is the ith user’
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nodes will be formed one cluster, t
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Error 8000 7000 6000 5000 4000 3000
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Architecture (AMBA) a new bus archi
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In this paper, we adopt two Sobel o
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four layers.The far right of the gr
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TABLE II. OPERATIONAL EMPLOYEE TABL
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A. Object-relational Type To audit
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to execution time. Also, DBA would
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Liping Chen .......................
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