1
Social Networks For Dummies
Or some clues about Distributed Knowledge Base with Privacy
Serge Abiteboul,
Alban Galland
and a bunch of different people
Webdam, INRIA Saclay
-
Ile
-
de
-
France
2
Summary
•
Introduction
•
Definitions
•
Goal
•
Related works
•
Distributed Knowledge Base with Privacy
•
Ask
-
owner implementation
•
Indexed
-
DHT implementation
•
Friendly
-
Gossip Implementation
•
Declarative Expression of Privacy
•
Social Knowledge Mining
•
Demonstration
•
Conclusion
3
My definition of Social Network
•
Social Network
: a (web)
application where users store
and consult data and interact
with data of other users
following explicit relationships
•
Some important notions
•
Users : people
•
Data : graph of XML
documents, AXML
•
Data
-
management : storage,
replication, query
•
Relationship
4
My definition of Privacy
•
Privacy
: the fact that a user
keeps control over her data and
activity
•
Some important notions
•
Read and write permissions
•
Delegation of permissions
•
(Anonymity of activity)
•
(Anonymity of aggregated data)
5
Goal
•
Define and implement the basis for a distributed
social network that guarantees access control
•
More precisely
•
Distributed knowledge base with access control
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Declarative high level access control specification
•
Also
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Social network application
•
Social knowledge mining
6
Related works
•
Social network
•
Some typically centralized SN systems with limited
access control management
•
Some SN
-
specific applications
•
Some works on knowledge mining in SN
•
Distribution
•
Distributed Hash Table and indexing (KadoP)
•
Friend based P2P
•
Privacy
•
Access control and logic
•
Cryptography
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Distributed Knowledge Base with Privacy
•
Access control lists at the principal level
•
A principal corresponds to a set of access rights
and documents
–
e.g., a user or a group
•
Rights : read (query), append, write (delete), own
(grant, revoke)
•
Some languages (logics) to speak about
cryptography and communications
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Signature, encryption
•
Time
•
Messages
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Distributed Knowledge Base with Privacy
•
One can consider different architectures/
implementations
•
We focus on (1+) 3
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(Centralized system)
•
Ask
-
owner implementation
•
Indexed
-
DHT implementation
•
Friendly
-
Gossip implementation
9
Ask
-
owner implementation
•
Basic semantic
Signed Instructions
Results
Ownership
10
Indexed
-
DHT implementation
Signed Instructions
Encrypted Results
Ownership
1
1
2
Access
Access
Index
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Indexed
-
DHT implementation
•
Principals are no more physically hosted by one
machine but data
are
distributed as posts on a P2P
system with a DHT
•
Each post is signed and encrypted.
Hosts :
•
Understand some meta
-
data
•
Do not understand the content they store
•
Three key kinds of posts : update (write or
append), access and index
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Indexed
-
DHT implementation
Update posts
•
q says (doc@q, t
apply
, T, C for q) where :
•
q : principal id
•
doc : document id
•
t
apply
: update timestamp
•
T : write or append
•
C for q : content encrypted by a reader public
key
•
Write/Append right = signature private key
•
A host can easily check it get a valid post
1
1
13
Indexed
-
DHT implementation
Update posts
•
Read right = reader private key
•
A reader can check she gets a valid
version, or otherwise ask another host
•
In the general case, hosts exchange signatures
on list of posts
•
If you forget about append, replication can be
replaced by time of validity and refresh
1
1
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Indexed
-
DHT implementation
Access posts
•
q says t
apply
,(key for u), (u,R for q)
where :
•
q : principal id
•
u : another principal
•
key : cryptographic key (explicit
delegation)
•
R : access right (read, write, append,
own)
•
Revocation : add time to post + full (or
lazy) regeneration of dirty keys
Access
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Indexed
-
DHT implementation
Index posts
•
Balance between leak of information
and efficiency of queries
•
May need more meta
-
data, like an
encryption schema
•
Could be managed as regular update
Index
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Indexed
-
DHT implementation
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Other versions depending of
•
Hierarchy of rights
•
Who can access the list of access controls of a
principal
•
Some reasons to use a logic language for access
control
•
Need a clear way to express the exchange of
knowledge
•
Need to make some proof
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Friendly
-
Gossip Implementation
Signed Instructions
Encrypted Results
Ownership
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Declarative Expression of Privacy
•
Example
•
People who are tagged on one of my photos can
see this photo
•
People who are friends of two of my friends can
read my Wall
•
People who are best friends of mine can write on
my Wall
•
Problems
•
Uncontrolled deduction
•
Fix
-
point semantic
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Social Knowledge Mining
•
Previous works
•
Recommendation: previous works at Yahoo!
Research with Sihem Amer
-
Yahia
•
Corroboration (with Serge, Amelie and Pierre S.)
•
What remains in a distributed system with access
control?
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Introducing higher level of semantic (belief…)
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Demonstration
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Some functionalities already implemented during
Marilena Oita internship
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A user interface and global logic
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Some part of Distributed Knowledge Base with
Privacy
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Declarative Privacy is missing
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Conclusion
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This is work in progress
•
We are currently focusing on distributed
knowledge base with access control, wondering if
there is any link with knowledge management
•
Hidden behind trendy Social Networks, we believe
there are real topics of research, in particular in
distributed systems
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