A Security Framework for a World of Post-PC Clients and Infrastructure-based Services Steven Ross, Jason Hill, Michael Chen, Anthony D. Joseph, David E. Culler, Eric A. Brewer Computer Science Division U.C. Berkeley {stevross, jhill, mikechen, adj, culler,

Typical (Traditional) Internet Service Assumes: Private / trusted access device and software Sufficient computational resources to secure connection and display content HTTP/SSL

Scenario: Kiosks - Untrusted Endpoints Public (untrusted) computers will be pervasive Content filter –hides private information Control filter –limits operations performed Decrease the content value instead of increasing the security level

Scenario: Low Power Info Appliances Limited computational abilities Low physical security Low reliability Limited input and display capabilities Users have multiple devices

Enable Secure Access from all Devices Security is fundamental to Universal Computing Tremendous diversity emerging –No pre-planning: wide array of services and clients –Info flowing over wide array of insecure links and clients Key leverage: Composable Secure Services –Automating scalability and availability eases task authoring –Build new services from component services Key Tool: Transcoding Operators –Adapt content, and security level to desired use

Bridging the Gap Stock Trading Banking Mail PDA Kiosk Cell Phone Pager Desktop Laptop Trusted Infrastructure Composable Security Framework

Content Transformers Client Side –Decouple device I/O capabilities from services –New client transformer enables access existing content Server Side –Transform content and control to canonical representation »Filtered by application logic »Easily rendered by client side content transformer CT c CT s Stock Trading Banking Mail PDA Kiosk Cell Phone Pager Desktop Laptop Trusted Infrastructure Composable Security Framework CT: Content Transformer

Security Adaptors Secure channel in depends on device capabilities Secure channel out depends on Internet service Examples –Low power info appliance –International Kiosk SA Stock Trading Banking Mail PDA Kiosk Cell Phone Pager Desktop Laptop Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer CT c CT s

Identity Service Secure repository Key component for enabling access from untrusted endpoints Critical level of indirection and information hiding Mitigates problem of replicating identities Promotes use of secure username/password pairs Identity Service SA CT c CT s SA Stock Trading Banking Mail PDA Kiosk Cell Phone Pager Desktop Laptop Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer

Filter and Control Modifier Identity Translation Add new or remove existing control functionality –Add logout button –Remove ability to trade, write checks, drop class, etc. Remove sensitive content –Account balances, addresses, names Identity Service SA CT c FCM CT s SA Stock Trading Banking Mail PDA Kiosk Cell Phone Pager Desktop Laptop Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from Kiosk Kiosk browser interacts with security adaptor Identity Service SA SSL CT c FCM CT s SA SSL Datek Kiosk Trusted Infrastructure Composable Security Framework SSL SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from Kiosk HTTP request passed to FCM no content transformer in prototype Identity Service SA SSL CT c FCM CT s SA SSL Datek Kiosk Trusted Infrastructure Composable Security Framework SSL SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from Kiosk FCM authenticates pseudonym and one time password Substitutes real identity Identity Service SA SSL CT c FCM CT s SA SSL Datek Kiosk User Identity Trusted Infrastructure Composable Security Framework SSL SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from Kiosk FCM passes substituted data through to outgoing security adaptor Identity Service SA SSL CT c FCM CT s SA SSL Datek Kiosk User Identity Trusted Infrastructure Composable Security Framework SSL SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from Kiosk SA communicates with Datek Service FCM Filters all remaining traffic –Removes sensitive information: i.e. account name, address –Performs control filtering: adds logout button Identity Service SA SSL CT c FCM CT s SA SSL Datek Kiosk User Identity Trusted Infrastructure Composable Security Framework SSL SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from PDA Pilot connects to security adaptor Identity Service SA Blowfish CT c FCM CT s SA SSL Stock Trading PDA Trusted Infrastructure Composable Security Framework Blowfish SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from PDA Shared secret key identity verified Identity Service SA Blowfish CT c FCM CT s SA SSL Stock Trading PDA Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from PDA Content transformer –simple pilot commands to http requests –html to plain text pilot app format Identity Service SA Blowfish CT c FCM CT s SA SSL Stock Trading PDA Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from PDA FCM examines HTTP requests performs identity substitution Identity Service SA Blowfish CT c FCM CT s SA SSL Stock Trading PDA Auth Client User Identity Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from PDA Modified packets sent to security adaptor Identity Service SA Blowfish CT c FCM CT s SA SSL Stock Trading PDA Auth Client User Identity Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Illustration: Datek Access from PDA Security Adaptor establishes HTTPS connection to Datek service Identity Service SA Blowfish CT c FCM CT s SA SSL Stock Trading PDA Auth Client User Identity Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Composable Security Framework Paths from devices to services can be dynamically created Multiple transcoders may be composed for a path Identity Service SA CT c FCM CT s SA FCM Stock Trading Banking Mail PDA Kiosk Cell Phone Pager Desktop Laptop Auth Client User Identity Auth Service Trusted Infrastructure Composable Security Framework SA: Security Adapter CT: Content Transformer FCM: Filter & Control Modifier

Key Design Points Security and Content both transformed –Security adaptors based on device capability and link –Information hiding based on device, user role, and link Composing services –Trust model must be carefully considered Extensible –New devices easily added by writing appropriate component if it doesn’t already exist Scalability/ Fault Tolerance –Runs in Ninja distributed execution environment –Components replicated among nodes in cluster

Other Applications Meta-trade environment –Aggregation: provide most valuable composition of content Multi-user or manager account –Owner of account can view all content –Account manager only views selected pieces essential to role –Example: Trade-bot only needs stock quotes and rules –Account value, and private information hidden from Trade-bot Short lived and persistent pseudonyms Support sharing of PDAs –Now have untrusted low power device –Compose kiosk FCM and PDA components to handle scenario

Security Assessment Untrusted endpoint –May still alter information Identity Service –A primary point to attack PDA Keys –I/O methods limit strength of generated keys Dynamic Trust Model –New Functionality added »I.e. Citibank online payment –User must explicitly grant functionality for each profile

Future Work Implementation of additional content, control and security transformer –Additional web services –Other services » IMAP, LDAP, e-commerce, etc –Additional Devices »Pagers, phones Development of common data change format for FCM –XML for canonical representation, XSL for rendering to device

Take-Away New security requirements of Post-PC devices –Supports access from insecure endpoints –Precise control of information exposure (access device / role) Composable Services in the infrastructure –New level of “programming” Towards an Architecture for Universal Computing –Diverse concurrent development: 1 to many, meta-svcs, aggregation svcs –Many to one, heterogeneous clients Eureka phenomenon –Most fundamental services probably yet to be discovered »Ex: identity service –Only find them by building the world and living in it

A Security Framework for a World of Post-PC Clients and Infrastructure-based Services Steven Ross, Jason Hill, Michael Chen, Anthony D. Joseph, David E. Culler, Eric A. Brewer Computer Science Division U.C. Berkeley {stevross, jhill, mikechen, adj, culler,