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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 A Distributed P2P Storage Service, Adaptive to Trust Assessment Marco Casassa Mont (marco_casassa-mont@hp.com ) Lorenzo Tomasi (University of Bologna) Trusted E-Services Laboratory (TESL) Hewlett-Packard Laboratories, Bristol, UK
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Table of Contents Background Trust E-Services Distributed Long-term Trusted E-Record Storage Distributed P2P Storage Service Model Conclusions & some Future Trends
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Trust E-Services Notary Restoration Services Restoration Services Access Control Evidential Analysis Evidential Analysis Identity tracking Identity tracking Storage -contracts -keys -evidential documents Storage -contracts -keys -evidential documents real time Monitoring real time Monitoring Reliable Messaging Reliable Messaging Underwriter Credential Management Credential Management Policy Transactions, contracts, agreements, e-records B2B, B2C, P2P, …
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Purpose: Long-term preservation of electronic documents Longevity of e-Documents (E-records) and Processes Survivability Long-term identity management and access control Long-term Renewal of information Long term Renewal of signatures & time-stamps Migration of data through technology Accountability Integrity Privacy & Confidentiality Non-Repudiation Authenticity Long-Term Trusted Storage
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Distributed Long-Term Trusted Storage Portals Storage SLAs E-Record (Evidence) E-Record Clusters: - Conversation - Bundle User/ Application Add Retrieve Modify Delete DERMS Services Distributed E-Records Management & Storage
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Portal Layer Indexing & Management Layer Physical Storage Layer Service Pool Management Service Pool Portal Storage Systems Application Layer Distributed Long-term Trusted Storage Architecture Replication: Stored Documents Metadata Randomness: Portals Service Pools Services Storages “Lazy transactional” behaviour Diversity Decentralization & Distribution Monitoring Self healing …
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 SAN, NAS, Distributed FSs, for example … Focus on rapid and frequent access to data Dedicated, expensive solutions Not really “Long-termed” Current Approach
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Research on alternative long-term storage service of e-records (for DERMS Services at the physical storage layer) Objectives Basic Requirements best-effort preservation a document for a long period storage, retrieval and deletion of documents Assumption High performance, rapid and frequent accesses are not a basic requirement
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 PCs: geographically distributed (survivability) Their storage capacity and CPU time are not fully used Alternative long-term Storage Service Context: Medium/Large Enterprise Dynamic (in the medium/long term): PCs employees/people Collaborative but unreliable not necessary trusted
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Research Issues Challenge: cope with a dynamic and unreliable environment Medium-Large enterprise: 15000 people PCs: 10000 PC obsolescence timeframe: 3-4 years Percentage of PCs involved in the service: 10% Number of PCs: 1000 Average obsolescence of involved PCs (per year): 250 (1/4* 1000) This without considering faults, loss of data, PC’s owner accidental and intentional data deletion, time zones, etc. ….
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Resources: distributed Trust: variable resources’ behaviour is very dynamic Control: variable not fully centralized (take advantage of distributed resources) not fully distributed (likely anarchic, need for a trusted access point for DERMS Services) Research Space: Choices Resources distributed centralized Control distributedcentralized Trust none full “Trust”: belief that someone/something is going to act and behave as expected
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 TrustedNot trusted DERMS Services A A A A A A A A Hybrid P2P Model ControllerPeers Agents installed on distributed PCs (not necessarily trusted, at least initially) Trusted controller, acting as Gateway with DERMS services
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 TrustedNot trusted A A A A A A A A Agent Installation (on Peers) Agents installed on requests (by PCs’ users)
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 TrustedNot trusted A A A A A A A A Storage, Retrieval, Deletion of E-Records DERMS Services - Replication of stored E-Records - Integrity Check during E-Record retrieval
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Tasks Delegation TrustedNot trusted A A A A A A A A DERMS Services - Delegation of Tasks to Peers (if Authorised)
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Peer-to-Peer Interaction Trusted Not trusted A A A A A A A A DERMS Services -Peer-to-Peer interaction triggered by an Agent (if Authorised)
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Are distribution and replication sufficient to achieve long-term storage? It depends … In case of dynamic environment, peers may: not be available lose data (or data may get corrupted) not be able to complete tasks “Blind” delegation of tasks to Peers Is this Sufficient?
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Need for an Adaptive System Monitor Distributed Peers Learn from Peers’ behaviour Adopt dynamic working criteria “delegation of tasks to peers” depending on peers’ reliability Select contextual policies depending on peers’ behaviour and environment dynamics
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Monitoring & Learning Monitoring Objectives: control replicas’ status (survivability) observe peers’ behaviour gather information about peers trigger reactions Learn about: Peers’ availability Peers’ reliability Correctness of document replicas Peers’ ability to complete tasks with success Peers’ response time …
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Aggregation of measures of reliability/ trustworthiness in Trust Rating Information Usage of Trust Rating Information to dynamically adapt service by making decision on allocation of storage and delegation tasks Delegation and Storage Policies driven by measures of trust Usage of “Trust and Reliability Functions” to define Trust Metrics based on measured indicators (parameters) Adaptation driven by “Trust Rating” “Trust”: belief that a Peer/Resource is going to act and behave as expected
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Communication Manager Engines (store, delete, retrieve, etc …) “Intelligent” components (Task Mgr, Monitoring, Rating) High Level Architecture Agents are a cut-down version of the centralized controller Architecture is modular
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 DERMS Services Communication Manager Index and Secure Repository Monitoring Module Rating Module Storage Module Task Manager Communication Manager Monitoring Module Rating Module Storage Module Task Manager Enterprise Central Control Component Agents Agent Secure Connections Secure Repository Local Storage Scheduler TRUSTED UNTRUSTED Secure Connections Registration High Level Architecture
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Communication: authentication based on secure link (SSL) Delegation: authorization token (SPKI based) Integrity management: hash value, digital signature Confidentiality: encryption Survivability: documents’ replication Basic Mechanisms
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Usage of distributed cheap resources and agents to underpin survivability of data over long time P2P architecture viable to decongest central control Hybrid control as a balance between full centralization and completely distributed control (anarchism) Trust Assessment to underpin adaptability in dynamic distributed environment Our approach: reduces risks in very dynamic environments (Best Effort) introduces overhead: … need for a “real-life” trial requires a sustained number of participants Conclusions
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Future Trends on Distributed Systems Growing importance of Distributed Web Services: - within Enterprises and across Enterprises (on the Internet) Key role for Trust Services to reduce Risks and increase Accountability Importance of Adaptability of Systems and Services to the behaviour of (the involved) resources (Reliability and Trustworthiness are crucial aspects to be considered) Growing importance of Peer-to-Peer based environments: - mobile systems/services, collaborative environments, dynamic business interactions, resource sharing, etc.
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Backup Slides
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Agents (on PCs) join or leave the Storage Service DERMS Service initiative: store, retrieve, delete Peer’s initiative Use Cases
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Use Case: Join
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Use Case: Store
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Use Case: Retrieve DERMS Services Collaborative Environment Central Control Component Peers Enterprise 1. Request to retrieve a document 2. Retrieve from the Index a list of location where the document has been stored 4. Decrypt and verify the integrity of the replica. If the replica is compromised, repeat step 3. 3. Retrieve a Replica 5. Return the document
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Use Case: Delete
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Use Case: Peer-to-Peer
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Use Case: Monitoring
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Use Case: Delegation of Monitoring Tasks
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Information base: basic information module and rating information module Monitoring module Rating module Engines for testing, storage, deletion, and retrieval Registration module keys and identities manager Communication manager High Level Architecture
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 Engines Monitoring Interaction with peers (via communication manager) May influence Information base May update Policy-based and “planning” components High Level Architecture
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 List of tasks Generator Delegation manager requests From/to information base Tasks manager Scheduler From/to engines Monitoring Module
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Marco Casassa Mont – TESL - Hewlett-Packard Laboratories, Bristol, UK 8 th IEEE Workshop FTDCS 2001 – Bologna - 31/10/2001-02/11/2001 “events” generator Trust function queries Information on peers’ behaviour notifications Rating information db Rating Module
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