Transcript Privacy and Identity Management in Cloud Rohit Ranchal, Bharat Bhargava, Pelin Angin, Noopur Singh, Lotfi Ben Othmane, Leszek Lilien Department of Computer Science Purdue University,

Privacy and Identity
Management in Cloud
Rohit Ranchal, Bharat Bhargava, Pelin Angin, Noopur Singh,
Lotfi Ben Othmane, Leszek Lilien
Department of Computer Science
Purdue University, Western Michigan University
{rranchal, bbshail}@purdue.edu, [email protected]
Mark Linderman
[email protected]
Air Force Research Laboratory
Rome, NY, USA
This research was supported by AFRL Rome, USA and NGC
Outline
Motivation
 Identity Management (IDM)
 Goals of Proposed User-Centric IDM
 Mechanisms
 Description of proposed solution
 Advantages of the Proposed Scheme
 Conclusion & Future Work
 References
 Questions?
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Motivation
User on
Amazon Cloud
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Name
E-mail
Password
Billing Address
Shipping Address
Credit Card
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Name
E-mail
Password
Billing Address
Shipping Address
Credit Card
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Name
E-mail
Shipping Address
Name
Billing Address
Credit Card
Name
E-mail
Shipping Address
Motivation
User on
Amazon Cloud
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Name
E-mail
Password
Billing Address
Shipping Address
Credit Card
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Name
E-mail
Password
Billing Address
Shipping Address
Credit Card
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Name
E-mail
Shipping Address
Name
Billing Address
Credit Card
Name
E-mail
Shipping Address
Identity Management (IDM)
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IDM in traditional application-centric IDM model
Each service keeps track of identifying information of its
users.
Existing IDM Systems
Microsoft Windows CardSpace [W. A. Alrodhan]
OpenID [http://openid.net]
PRIME [S. F. Hubner, Karlstad Univ]
These systems require a trusted third party and do not work on
an untrusted host.
If Trusted Third Party is compromised, all the identifying information
of the users is also compromised leading to serious problems like
Identity Theft.
[Latest: AT&T iPad leak]
IDM in Cloud Computing
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Cloud introduces several issues for IDM
◦ Collusion between Cloud Services
 Users have multiple accounts associated with multiple service
providers.
 Sharing sensitive identity information among services can lead to
undesirable mapping of the identities to the user.
◦ Lack of trust
 Cloud hosts are untrusted
 Use of Trusted Third Party is not an option
◦ Loss of control
 Service-centric IDM Model
IDM in Cloud needs to be user-centric
Goals of Proposed User-Centric IDM
for the Cloud
1. Authenticate
without disclosing
identifying information
2. Ability to securely use a service while on
an untrusted host (VM on the cloud)
3. Minimal disclosure and minimized risk of
disclosure during communication
between user and service provider
(Man in the Middle, Side Channel and
Correlation Attacks)
4. Independence from Trusted Third Party
for identity information
Mechanisms in Proposed IDM
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Active Bundle [L. Othmane, R. Ranchal]
Anonymous Identification [A. Shamir]
Computing Predicates with encrypted data [E. Shi]
Multi-Party Computing [A. Shamir]
Selective Disclosure [B. Laurie]
Active Bundle
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Active bundle (AB)
– An encapsulating mechanism protecting data carried within
it
– Includes data
– Includes metadata used for managing confidentiality
• Both privacy of data and privacy of the whole AB
– Includes Virtual Machine (VM)
• performing a set of operations
• protecting its confidentiality
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Active Bundles—Operations
– Self-Integrity check
E.g., Uses a hash function
– Evaporation/ Filtering
Self-destroys (a part of) AB’s sensitive data when threatened with a disclosure
– Apoptosis
Self-destructs AB’s completely
Active Bundle Scheme
– Metadata:
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E(Name)
E(E-mail)
E(Password)
E(Shipping Address)
E(Billing Address)
E(Credit Card)
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Access control policies
Data integrity checks
Dissemination policies
Life duration
ID of a trust server
ID of a security server
App-dependent information
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– Sensitive Data:
• Identity Information
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– Virtual Machine (algorithm):
• Interprets metadata
• Checks active bundle integrity
• Enforces access and
dissemination control policies
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* E( ) - Encrypted Information
Anonymous Identification
• Use of Zero-knowledge proofing for user
authentication without disclosing its identifier.
User on Amazon
Cloud
ZKP Interactive Protocol
User Request for service
Function f and number k
fk(E-mail, Password) = R
1. E-mail
2. Password
Authenticated
1. E-mail
2. Password
Interaction using Active Bundle
AB information disclosure
Active Bundle Destination
User Application
Active Bundle
Active Bundle
Creator
Active
Bundle (AB)
Security Services
Agent (SSA)
Directory
Facilitator
Active Bundle Coordinator
Trust Evaluation
Agent (TEA)
Active Bundle Services
Audit Services
Agent (ASA)
Predicate over Encrypted Data
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Verification without disclosing unencrypted identity data.
Predicate Request*
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E-mail
Password
E(Name)
E(Shipping Address)
E(Billing Address)
E(Credit Card)
*Age Verification Request
*Credit Card Verification Request
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E(Name)
E(Billing Address)
E(Credit Card)
Multi-Party Computing
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To become independent of a trusted third party
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Multiple Services hold shares of the secret key
Minimize the risk
Predicate Request
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K ’1
K ’2
E(Name)
E(Billing Address)
E(Credit Card)
K ’3
K ’n
Key Management Services
* Decryption of information is handled by the Key Management services
Multi-Party Computing
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To become independent of a trusted third party
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Multiple Services hold shares of the secret key
Minimize the risk
Predicate Reply*
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K ’1
K ’2
Name
Billing Address
Credit Card
K ’3
Key Management Services
*Age Verified
*Credit Card Verified
K ’n
Selective Disclosure
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User Policies in the Active Bundle dictate dissemination
Selective disclosure*
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E-mail
Password
E(Name)
E(Shipping Address)
E(Billing Address)
E(Credit Card)
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E-mail
E(Name)
E(Shipping Address)
*e-bay shares the encrypted information based on the user policy
Selective Disclosure
Selective disclosure*
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E-mail
E(Name)
E(Shipping Address)
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E(Name)
E(Shipping Address)
*e-bay seller shares the encrypted information based on the user policy
Selective Disclosure
Selective disclosure
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E-mail
E(Name)
E(Shipping Address)
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Name
Shipping Address
Decryption handled by Multi-Party Computing as in the previous slides
Selective Disclosure
Selective disclosure
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E-mail
E(Name)
E(Shipping Address)
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Name
Shipping Address
Fed-Ex can now send the package to the user
Identity revealed in the Cloud
User on Amazon
Cloud
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E-mail
Password
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Name
E-mail
Password
Billing Address
Shipping Address
Credit Card
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Name
Shipping Address
E-mail
Name
Billing Address
Credit Card
Characteristics and Advantages
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Ability to use Identity data on untrusted hosts
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Establishes the trust of users in IDM
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Through putting the user in control of who has his data
and how is is used
Identity is being used in the process of authentication,
negotiation, and data exchange.
Independent of Third Party for Identity Information
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Self Integrity Check
Integrity compromised- apoptosis or evaporation
Data should not be on this host
Minimizes correlation attacks
Minimal disclosure to the SP
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SP receives only necessary information.
Conclusion & Future Work
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Problems with IDM in Cloud Computing
◦ Collusion of Identity Information
◦ Prohibited Untrusted Hosts
◦ Usage of Trusted Third Party
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Proposed Approaches
◦ IDM based on Anonymous Identification
◦ IDM based on Predicate over Encrypted data
◦ IDM based on Multi-Party Computing
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Future work
◦ Develop the prototype, conduct experiments and
evaluate the approach
References
[1] C. Sample and D. Kelley. Cloud Computing Security: Routing and DNS Threats,
http://www.securitycurve.com/wordpress/, June 23,2009.
[2] W. A. Alrodhan and C. J. Mitchell. Improving the Security of CardSpace, EURASIP Journal on
Information Security Vol. 2009, doi:10.1155/2009/167216, 2009.
[3] OPENID, http://openid.net/, 2010.
[4] S. F. Hubner. HCI work in PRIME, https://www.prime-project.eu/, 2008.
[5] A. Gopalakrishnan, Cloud Computing Identity Management, SETLabsBriefings,Vol7,
http://www.infosys.com/research/, 2009.
[6] A. Barth, A. Datta, J. Mitchell and H. Nissenbaum. Privacy and Contextual
Integrity: Framework and Applications, Proc. of the 2006 IEEE Symposium on Security and
Privacy, 184-198.
[7] L. Othmane, Active Bundles for Protecting Confidentiality of Sensitive Data throughout Their
Lifecycle, PhD Thesis, Western Michigan Univ, 2010.
[8] A. Fiat and A. Shamir, How to prove yourself: Practical Solutions to Identification and
Signature Problems, CRYPTO, 1986.
[9] A. Shamir, How to Share a Secret, Communications of the ACM, 1979.
[10] M. Ben-Or, S. Goldwasser and A. Wigderson, Completeness theorems for noncryptographic fault-tolerant distributed computation, ACM Symposium on Theory of
Computing, 1988.
[11] E. Shi, Evaluating Predicates over Encrypted Data, PhD Thesis, CMU, 2008.
Thank you!
Any question?
Approach - 1
IDM Wallet:
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Use of AB scheme to protect PII from untrusted
hosts.
Anonymous Identification:
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Use of Zero-knowledge proofing for authentication
of an entity without disclosing its identifier.
Components of Active Bundle
(Approach – 1)
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Identity data: Data used during authentication,
getting service, using service (i.e. SSN, Date of
Birth).
Disclosure policy: A set of rules for choosing
Identity data from a set of identities in IDM
Wallet.
Disclosure history: Used for logging and
auditing purposes.
Negotiation policy: This is Anonymous
Identification, based on the Zero Knowledge
Proofing.
Virtual Machine: Code for protecting data on
untrusted hosts. It enforces the disclosure
policies.
Anonymous Identification (Approach –
1)
Anonymous Identification
(Shamir's approach for Credit Cards)
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IdP provides Encrypted Identity
Information to the user and SP.
SP and User interact
Both run IdP's public function on the
certain bits of the Encrypted data.
Both exchange results and agree if it
matches.
Usage Scenario (Approach – 1)
Approach - 2
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Active Bundle scheme to protect PII
from untrusted hosts
Predicates over encrypted data to
authenticate without disclosing
unencrypted identity data.
Multi-party computing to be independent
of a trusted third party
Usage Scenario (Approach – 2)
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Owner O encrypts Identity Data(PII) using
algorithm Encrypt and O’s public key PK. Encrypt
outputs CT—the encrypted PII.
SP transforms his request for PII to a predicate
represented by function p.
SP sends shares of p to the n parties who hold
the shares of MSK.
n parties execute together KeyGen using PK,
MSK, and p, and return TKp to SP.
SP calls the algorithm Query that takes as input
PK, CT, TKp and produces p(PII) which is the
evaluation of the predicate.
The owner O is allowed to use the service only
when the predicate evaluates to “true”.
Representation of identity
information for negotiation
Token/Pseudonym
Identity Information in clear plain text
Active Bundle
Motivation:
Authentication Process using PII
Problem: Which information to disclose and how to
disclose it.