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Porscha : policy oriented secure content handling in android. Dhurakij Pundit University, University of Oregon, Pennsylvania State University ACSAC(2010 ). Machigar Ongtang , Kevin Butler, Patrick McDaniel. Agenda. Introduction Content on Smart Phone About Android Architecture
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Porscha : policy oriented secure content handling in android Dhurakij Pundit University, University of Oregon, Pennsylvania State UniversityACSAC(2010) MachigarOngtang, Kevin Butler, Patrick McDaniel
Agenda • Introduction • Content on Smart Phone • About Android • Architecture • Evaluation • Discussion • Conclusion
Introduction • Android provide few direct protections for the content placed on the phone • DRM(Digital Right Management) • Porscha: • content should only be accessible by explicitly authorized phones • content should only be accessed by provider endorsed applications • content should be subject to contextual constraints • Two phases of Porscha: • in transit • on platform
Content on Smart Phone • Personal and Business Documents • Service-specific data • spy camera • Mydroid • Financial Information
Content on Smart Phone • DRM Policy Requirements • Binding content to the phone • Binding content to endorsed applications • Constraining continuing use of the content
About Android • Four types of components • Two groups of applications • Documents in transit & on-platform access
About Android • On-platform access • Initial Document Recipients • Documents at Rest • Document Sharing
Architecture • Constraints on Devices-binding to specific devices identified by the users' International Mobile Subscriber Identity (IMSI)or WAP Identify Module (WIM). • Constraints on Applications-be restricted to applications with a given code fingerprint (hash of the application image) • Constraints on Use-support not only the regulation of simple accesses, but also differentiation of simple access from read, modify and delete rights
Architecture-in transit • Identity-Based Encryption (IBE):enables the senders to construct the public keys of the recipients from known identities, and contains a trusted Private Key Generator(PKG). • Encryption: inputting the message (data), public key string, and cryptosystemparameters • Decryption:inputting the ciphertext and privatekey to the decryption algorithm
Architecture-in transit • sender(content source) : S • receiver(phone) : R • identity for participant s : Is • public/private key of a :Ka+/Ka- • content : m • police for m : pm • ------------------------------------------ • Delivery of SMS/MMS:
Architecture-in transit • Delivery of email: • one-time 128-bitAES symmetric key : ke
Architecture-on platform • Policy Enforcement on Initial Recipients
Architecture-on platform • Email traffic is opaque to Android • Use the Apache Mime4j library to parse the e-mail message streams in plain RFC-882 and MIME formats
Architecture-on platform • Policy Enforcement on Documents at Rest • add an extra policy field to the structureof each Content Provider record • The Porscha mediator insertsthe policy into this field
Architecture-on platform • Enforcement on Indirect Receivers
Discussion • Recipients Without Porscha • store all modifications such as decrypted emails and those with information removed, locally on the phone, and only reflect back to the IMAP server the original email • Application and Platform Trust • Alternative Application Enforcement Infrastructures • Digital Rights Management • Porscha islightweight and designed with mobile solutions in mind; bycontrast, many advanced DRM protocols are heavyweightand not transparent to applications.
Conclusion • Porscha can protect SMS, MMS, Email document. • Porscha secures content delivery using identity-based encryption and mediates on-platform content handling to ensure conformance with content policy