Spheres of Influence:Secure organization and coordination

of diverse device communities

Spheres of Influence:Secure organization and coordination

of diverse device communities

Kevin Eustice

January 28th, 2005

Kevin Eustice

January 28th, 2005

2

Roadmap

• Managing ubiquitous computing

• Our approach: device communities

• Related work

• Research Challenges

• Spheres of Influence: Design and Implementation

-Architecture-Connection Management

-Application Logic-Security

3

Ubiquitous Computing

Work has been focused in several areas:

• Smart environments (MIT, CMU, UIUC, UMD,…)

• Location & Context-aware support

• Specialized environment-specific applications (frequently, sensor + UI)

Few projects or technologies have transitioned to the real world.

4

Device Communities

We see device communities as an emerging trend in networking

• Personal Device Communities– Communities organized by common owner– Multi-device users require multi-device management– Bluetooth/802.11/GPRS

• Physical Location Communities– Communities organized by proximity/physical network– Basic model adopted by traditional ubicomp

infrastructure developers– Devices in a given location want to interact

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Device Communities (cont.)

• Social Communities are the latest addition– Community organized by social structure– Social computing is entering the limelight in it’s varied

forms• IM/chat communities• Blogs, moblogs, DC++• Friendster, orkut, tribes.net

• Connections beginning to be formed:• AT&T “Find Friends” • Vodafone “Buddy Alert” • Dodgeball.com

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Can we design scalable infrastructure to support device communities operating in multiple heterogeneous contexts (social, location, personal)?

Will novel applications or a new application paradigm arise from such an infrastructure?

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Thesis: Spheres of Influence

Device community based infrastructure, focused on:– Membership– Communication– Security

A sphere is a software entity representing either a device or set of other spheres that interact within a shared, secure boundary

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Spheres of Influence (cont.)

• Spheres can join together to form a set of spheres

• Sphere membership implies access to local sphere resources, events

• Each sphere possesses– Policy (limits internal interactions)– Requirements (properties it seeks from others)– Credentials (secure attestations of identity or

membership)

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Spheres of Influence (cont.)

Spheres serve as a scoping mechanism for:• Policy• Privilege• EventsSpheres can represent arbitrarily complex

arrangements of devices:• Personal device clusters• Physical locations (hierarchically arr.)• Social groups

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SoI Vision

Provide management infrastructure for communities of devices, enabling:– Dynamic group-based management of mobile

and infrastructure-based devices– Context-scoped resource discovery, event

handling– Establishment of secure boundaries– Attestable membership– Improved scalability

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SoI Vision (cont.)

• Membership and connections flow and adjust as users move with their devices throughout their environment

• As connectivity is acquired, devices negotiate with new hosting environment for necessary resources and acquire new policy

• Outside memberships are reasserted, queued messages/events are delivered

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Laboratory for Advanced Systems Research

Boelter Hall

Boelter 3564

Kevin

Kevin

Network Connections to Social Spheres through

Phys. Sphere

Physical Sphere

Social Sphere

Personal Device Sphere

Kevin

Network Connection to Physical Sphere

Friends

Kevin

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Anticipated Benefits

• Performance

• Security

• Vehicle for Application Innovation

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Performance Benefits

• Potential overhead savings for multi-device mobility

• Improved scaling through aggressive use of structured groups

• Improved spatial reuse through diverse groups and intelligent management of wireless spectrum

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Security Benefits

• Security boundary: dynamic firewall rules protect sphere members from outside world

• Defense-in-depth: layered security protects sphere structure

• Context attestation: spheres can provide secure, verifiable attestations of membership to members for access control or application purposes

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Applications Innovation

• Customized content based on community membership

• “Group as User”—new applications that focus on the group as the application user– Semantics for group application decisions?– UI for group applications?

• Support for “trails” type applications, in multiple contexts

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Legacy Wireless LAN

Mobile cluster example

E D

C

BA

N-times:•Acquire address (DHCP, bootp, …)•Rebind to network (VPN, mobile IP, IPsec, …)•Identify and reacquire resources (proxies, etc.)

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Physical Sphere

Mobile cluster example

Once:•Join protocol•Negotiate for access•Attach to other spheres

K

E D

C

BA

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Legacy IM example

K’s home machine

K’s work machine

K’s phone K’s PDA

IM Server

Id,logs

Id,logs

Id,logs

Id,logs

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Sphere-basedIM example

K’s home machine

K’s work machine

K’s phone K’s PDA

IM Server

K’s PersonalSphere

IM ID,logs

Cred. Cred. Cred. Cred.

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Related Work

• Protection Domains– 60s-70s work defining protection boundaries in single

machine

• ZeroConfig– WZC: Automatic configuration of wireless settings

based on observed network and (trivial) policies– Rendezvous: Apple solution for locating printers, file

servers, wireless APs, local http servers

• Ad-hoc Formation of Security Domains• Mobile Publish-Subscribe Systems

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Research Issues

• Sphere Management

• Sphere Mobility Management & Discovery

• Policy and Negotiation for Spheres

• Context Attestation

• Event Flow

• Sphere Enrollment

• Group as User

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SoI Design

Three principal components:• Doorman: External interactions• Sphere Manager: Internal interactions• Policy Manager: Consulted by other

componentsAlso necessary:• Relational Primitives: Support application

reasoning regarding sphere membership, relationships.

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Doorman

• Beaconing/Advertisement

• Discovery/Rendezvous

• Connection management– Accept incoming supplicants– Request outgoing join requests

• Queries policy manager for join approval

• Delivers events in observed external state to sphere manager

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Sphere Manager

• Coordinator for Sphere

• Maintains connections to relatives

• Manages events– Registration– Processing– Delivery

• Firewall manager

• Sphere state container

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Policy Manager

• Policy Manager: – Policy database contains local policy rules– Policy engine answers questions regarding

state changing interactions and local policy

• Policy Language– Describes valid interactions in terms of

relational, deontic, and temporal constraints– Logic-based

Focus of V. Ramakrishna’s research

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Relational Logic

• Applications and infrastructure need to be able to talk about relationships

• Primitives must describe basic relations:– Parent– Child– Sibling– Related

• Other properties: active, attested, etc.

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Sphere Manager

PolicyManager

Sphere StateMember tableAccess Rights

Event Registration…

Doorman

Simple Sphere

Policy CacheFast Path

Policy CacheFast Path

Int.EventIface

Ext.EventIface

App 1Connection to

any related Spheres

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Managed Sphere S

IEISM

PMState

DM

Members of SEEI

Candidates of S

Co

OCi

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Dissertation Plan

• Initial Implementation of Simple Spheres– No resources– Focus on membership and events

• Implement sample applications– Sphere-based IM application– Context-weighted task manager– Interactive fiction application– “Door monitor” application for LASR

• Evaluate implementation– Overhead of operations (join, event handling)– Scalability

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Dissertation Plan

• Extend design to support resources and services

• Extend implementation

• New applications?

• Evaluate implementation

• Write dissertation

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Contributions

• Model for a consistent representation of device membership spanning heterogeneous communities

• Secure, active management of community memberships

• Secure, cryptographic membership attestation• Logic to reason about membership,

relationships, and community transitions• Intra- and Inter-community event registration and

delivery• Evaluation of model with applications