Privacy in Cloud Computing Identity Management System for Cloud Microsoft CardSpace

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Privacy in Cloud Computing Identity Management System for Cloud Microsoft CardSpace. Purdue University. Outline. 1. Introduction 2. Laws of Identity Management 3.Microsoft CardSpaces Model of Identity Management 4.CardSpace Framework 5.Improving Security of CardSpace - PowerPoint PPT Presentation

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  • Privacy in Cloud ComputingIdentity Management System for Cloud Microsoft CardSpace

    Purdue University

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    Outline1. Introduction2. Laws of Identity Management3.Microsoft CardSpaces Model of Identity Management4.CardSpace Framework5.Improving Security of CardSpace 5.1 Proposed Approaches6. Conclusion

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    Identity Management SystemManages the digital identity of cloud users.Creates digital identities for its user entities and protects their Personally Identifiable Information (PII). Allow users to authenticate themselves, without revealing their actual identity to either vendors or network providers.The user has the ownership of the identity management data.Control the flow of dynamic personal information by the user, over the cloud.Support pseudonyms and multiple and discrete identities to protect user privacy .Minimize the amount of the personal data which a user needs to share with the Relying Party .Having a store of multiple digital identities (Gmail account, network account) with various service providers like e-bay, Gmail available to one entity (e.g., application) helps to uniquely identify a single person.If not properly protected maybe exploited and abused.Identity management data may be accessed from the cloud by authorized entities

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    2.. Laws of Identity ManagementKim Camerson (Microsoft) has identified 7 laws which are meant to be fundamentals of a conformed Identity Management System, of which the following three laws must be basics of any IDM system: [1] User Control and Consent: An identity management system must only reveal information identifying user with a users consent (Law 1)

    Minimal Disclosure for a constrained Use: An identity system must disclose the least amount of identifying information possible. (Law 2)

    Justifiable Parties: Identity systems must be designed so the disclosure of identifying information is limited to parties having a necessary and justifiable place in a given identity relationship. (Law 3)

    Directed Identity: An identity system should support both Omni-directional identifiers for use by public entities, and unidirectional identifiers for use by private entities, in order to facilitate discovery while preventing unnecessary release of correlation handles. (Law 4 )

    http://www.identityblog.com

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    3. CardSpace Model of Identity Management[2]

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    4. Microsoft Windows CardSpaceWindows CardSpace is an Identity-metasystem which provides a way, for managing multiple digital identities of a user [2] .It is a new claims based access platform/ architecture, developed for windows XP and is a plug-in for Internet explorer 7 browser. [3] The CardSpace is designed to comply with the seven Laws of identities by Kim Cameron of Microsoft [4].In CardSpace every digital identity transmitted on the network contains some kind of security token. A security token consists of a set of one or more claims, such as a username, a user's first name, last name, home address and even more sensitive information such as SSN, credit card numbers. These security tokens provide information in order to prove that these claims really do belong to the user who's presenting them {authenticating the identity of the user}. To make it user friendly, CardSpace implements an intuitive user interface for working with digital identities in form of a visual information card, Infocard, for them to make good decisions about using their digital identities, hence user-centric.

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    4. CardSpace Framework The CardSpace makes use of open XML-based protocols, including Web services (WS-*) protocols and SOAP. The following steps describe message flows of the CardSpace framework: [5]CEUA (CardSpace enabled user agent/service requestor) RP The CardSpace enabled user agent, CEUA (CardSpace enabled browser) requests a service from the relying party, using HTTP and gets a HTTP gets Login HTML Page Request.

    (2) RP CEUA: HTML Login Page + InfoCard Tags (XHTML or HTML object tags) The RP identifies itself using a public key certificate (e.g. a SSL/TLS certificate) and declares itself as a CardSpace enabled RP using XHTML or HTML object tags, i.e. a CardSpace enabled website or service provider.(3) CEUA RP: CEUA retrieves security policy via WS-Security Policy If the RP is card enabled, the CEUA obtains the RPs security policy described using WS-Security, this policy is retrieved using WS-Metadata Exchange (protocol suites for establishing/ verifying identity and any aspects necessary for using that protocol suite). This policy includes things such as what security token formats the RP will accept, exactly what claims those tokens must contain, and which Idp (identity provider) are trusted to makes such assertions, in order for this user to be granted the service.

    (4) CEUA User: User picks an InfoCard In this step the User matches the RPs security policy with an appropriate InfoCard (containing the type of security token required by the RP), which satisfies the RPs policy. After the user selects an Infocard, the CEUA initiates a connection with the Idp that issued the Infocard, and step 5 follows.

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    4. CardSpace Framework(5) CEUA IdP : User Authentication The user performs authentication process with the Idp, either using username/password login or using self-issued InfoCard. This is done for the user to prove the ownership of the InfoCard being used.(6) CEUA IdP: CEUA retrieves security token via WS-Trust If the authentication is successful the user requests the Idp to provide a security token which holds an assertion of the truth of the claims listed within the selected InfoCard. The CEUA obtains the security token using WS-trust.

    (7) CEUA RP: CEUA presents the security token via WS-Security Finally the CEUA forwards the security token to the RP using WS-Security.

    (8) RP CEUA: Welcome, you are now logged in! If the RP is able to verify the security token, the service is granted to the user.

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    5. Improving Security of CardSpaceAlthough CardSpace replaces Password-Based Web logins (preventing Phishing), with that of using digital security certificates/ tokens, there are certain security limitations in its framwork [5]:

    1. Users Judgements of RP Trustworthiness In the CardSpace framework, the user is prompted for its consent to be authenticated to an RP using a particular InfoCard, the user makes a judgment regarding the trustworthiness of the RP (step 2). Although, Microsoft recommends that the user should only make use of a high assurance certificate such as an X.509 certificate. Most users do not pay much attention when they are asked to approve a digital certificate, either because they do not understand the importance of the approval decision or because they know that they must approve the certificate in order to get access to a particular website. RPs without any certificates at all can be used in the CardSpace framework. Even if the RP presents a higher-assurance certificate, the user still needs to rely on an Idp who is providing that certificate to the RP and the user need to trust the Idp. Therefore, higher-assurance certificates do not solve this problem completely.

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    5. Improving Security of CardSpace2. Reliance on a Single Layer of AuthenticationThe security of the CardSpace identity metasystem relies on the authentication of the user by the IdP (step 5). In a case where a single IdP and multiple RPs are involved in a single working session, which we expect to be a typical scenario, the security of the identity metasystem within that working session will rely on a single layer of authentication, that is, the authentication of the user to the IdP. This user authentication can be achieved in a variety of ways (e.g., using an X.509 certificate, Kerberos v5 ticket, self-issued token or password); however, it seems likely that, in the majority of cases, a simple username/password authentication technique will be used. If a working session is hijacked (e.g., by compromising a self-issued token) or the password is cracked (e.g., via guessing, brute-force, key logging, or dictionary attacks), the security of the entire system will be compromised.

    How do we bypass these Security Limitations?The goal is to prevent the need to reveal the actual values of the claims to any party within the CardSpace framework, this way no party will have to trust any other party to the level that it has to reveal the actual values of the claims to it.

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    5.1 Proposed ApproachesUse of Zero-Knowledge Proofing and Selective Disclosure with a ZKP, it is possible to prove a claim or assertion without actually disclosing any credentials.The solution using a ZKP works as follows. For instance, a service requires a user to be over 18. The user wants to satisfy the relying partys technical policy but tell the party nothing or as little as possible. He need not to reveal his date of birth, just needs to somehow prove being over 18. This proves something without revealing all.

    Fig. Use of ZKP during Negotiation

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    5.1 Zero-Knowledge Proofing, Selective DisclosureZKPs are possible with cryptography. Few popular ZKP schemes that are available for example Fiat-Shamir proof of identity protocol: [6]

    1. A trusted center chooses n=pq, and publishes n but keeps p and q secret.2. Each prover A chooses a secret s with gcd(s,n)=1, and publishes v=s2 mod n. 3. A proves knowledge of s to B by repeating: (a) A chooses random r and sends r2 mod n to B. (b) B chooses random e in {0,1}, and sends it to A. (c) A responds with a=rse mod n. (d) B checks if a2 = ve r2 mod n. If A follows the protocol and knows s, then B's check will always work Iff A does not know s, then they can only answer the question with probability 1/2.

    The value of n should be digitally signed by the Idp by including it within the security token for example: XML- signature within a SAML assertion.

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    5.2 ZKP in SAML security tokenSecurity Assertions Markup Language (SAML) tokens are XML representations of claims. [7]

    C#

    Claim myClaim = new Claim( ClaimTypes.GivenName, "Martin", Rights.PossessProperty);SamlAttribute sa = new SamlAttribute(myClaim);

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    6. Conclusion

    Improve security of cardspace using ZKP.Adopt CardSpace for cloud as apposed to just for Web Services Access.

    Information on CardSpace Implementation:----The CardSpace Login Control for Asp.Net http://www.qualitydata.com/products/windows-cardspace/asp-net-information-card-login.aspx

    --- Project CardSpaehttp://www.codeproject.com/KB/WC/Introducing_Cardspace.aspx

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    REFERENCES:[1] K. Camerson et al. Proposal for a Common Identity Framework: A user-Cenctric Identity Metasystem, http://www.identityblog.com/, October 05, 2008.[2] Introducing Windows CardSpacehttp://msdn.microsoft.com/en-us/library/aa480189.aspx

    [3] http://en.wikipedia.org/wiki/Windows_Live_ID

    [4] CLAIMS-BASED IDENTITY FOR WINDOWShttp://download.microsoft.com/download/7/D/0/7D0B5166-6A8A-418A-ADDD-95EE9B046994/Claims-Based%20Identity%20for%20Windows.pdf[5] W. A. Alrodhan, C. J. Mitchell, Improving the Security of CardSpace, EURASIP Journal on Information Security Vol. 2009, doi:10.1155/2009/167216, 2009.[6] Zero knowledge example Fiat-Shamir proof of identityhttp://pages.swcp.com/~mccurley/talks/msri2/node24.html[7] SAML Tokens and Claims -msdnhttp://msdn.microsoft.com/en-us/library/ms733083.aspx

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