pVault Sharing Architecture - PowerPoint PPT Presentation

Title: pVault Sharing Architecture


1
pVault Sharing Architecture

• Ravi Chandra Jammalamadaka

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pVault Secure Personal Data Manager

• Users use the same passwords across different
  sites including secure and insecure sites which
  cannot be trusted .
• As a result same password attacks become
  common.
• Only solution is to remember a strong password
  for every website that requires password
  authentication.
• How many strong passwords can we remember ??

3
pVault features

• Stores passwords securely in a remote location.
• Generates strong passwords during registration.
• Provides mobile access of passwords.
• Autofills the required password on the website
  visited.
• Prevents Pharming and Phishing attacks

4
Download pVault

• pVault websites
• http//www.itr-rescue.org/pVault
• http//www.responsphere.org/pVault

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pVault Entry

• Based on XML
• All pvault entries are XML documents which follow
  a particular schema.
• Stores personal data (secrets) that belongs to
  more than one URL.

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pVault Entry schema
id
Keywords
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Design Criteria

• Store pvault entries in a relational database at
  the server (i.e. No changes at the server).
• Minimal Client side software and data storage.
• Allow both group sharing and sharing with
  individuals.
• PKI based

8
Security Consideration

• Data confidentiality Protecting data from
  being accessed from unauthorized users.
• Data Integrity Prevent tampering of the data
  at the server side.

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Privacy Policy
Rule Syntax
ltobjectgt lt subjectgt ltAccess Modesgt
Group id/User Id
Leaf node in the pvault entry
Read/Write
Example \\pvault_entry Ravi read
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XML subtree encryption
Encrypted_Node
id
Name
Individual_Secret
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Structure Preserving encryption
pVault_Entry


Secret
url

E(Id)
Metadata
E(Name)
E(Actualdata)
Individual_Secret

E(keywords)
E(Metadata)
E(Actualdata)
12
Issues

• There is no requirement to hide the structure
  of the pvault entry from the server. ( public
  knowledge)
• Just Encrypt the content of the leaf nodes,
  structure preserving.
• Allows queries to be run at the server side.

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Creating a Pvault Entry
E (PE)
K
E ( K )
P
A
E ( K )
P
E ( PE)
A
K
Server
PE
K
User A
14
Reading a Pvault Entry
E (PE)
K
E (PE)
K
E (K)
P
A
E (K)
P
A
User A
15
Writing a pVault Entry

• Execute the read protocol
• Update the PE
• Replace the previous PE.

16

Sharing Protocol
E (PE)
K
E ( PE)
E (PE)
K
K
A
B
E ( K)
E ( K)
E ( K)
P
E ( K)
P
P
B
P
A
A
B
Server
E ( K)
P
B
PE
K
K
PE
User A
User B
17
Data Integrity

• Since the Data is Stored at an Untrusted
• site, the service provider can
• 1. Modify data objects
• 2. Delete data objects
• 3. Not send the correct query
• results
• How do we prevent the Service Provider from
  doing above ??

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XML Integrity
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Another Method
pVault_Entry
urlcount


secretcount
Secret
Secret_count
url
id

Metadata
Name
Actualdata
Individual_Secret

metadatacount

Keywords
Metadata
Actualdata
20
Drawbacks

• How is access to a pvault entry revoked ?
• Re-encrypt the pvault and update the key
  entries for other users.
• Similar deal when a user leaves a group.
• Re-encryption Inevitable.
• Burden for the client.

21
Using Server as a Certificate Authority

• Since the server is untrusted, the server can
  lie about the public key.
• When Alice wants to share a file with Bob, Alice
  requests the public key from the server.
• The server can generate a new public key/private
  key pair and return the public key as Bobs
  public key.
• The sever now has access to all the files that
  Alice shares with Bob.

22
Secure Coprocessor

• SC is a general purpose computer that can be
  trusted faithfully to perform a computation.
• SC are resistant against forseeable physical and
  logical attacks, except DOS attacks.
• Trusted Third Party
• IBM 4758 SC is equipped with 99Mhz and 2 MB
  onboard memory.

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Secure Coprocessor Duties

• Provide access to private keys of pvault users.
• During revocation, re-encrypt pvault entries.

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Lost Update Problem

• Client/User requests an update on pvault entry
  o to change its content from c to c .
• The server ignores the update.
• The next time the pvault entry o is queried the
  server return c as the pvault entrys content.
• How can the client be sure about the freshness
  of the pvault entrys content??
• - Maintain Version numbers.