Data Protection and String Search in SDDS-2005

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Data Protection and String Searchin SDDS-2005

http//ceria.dauphine.fr/Riad/PagePersoRiad.html
Riad Mokadem
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SDDS-2005

• Evolution of SDDS-2004
• Existent Functions
• Extension of algebraic signatures
• Introduction of Pre-computed algebraic signature

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Cumulative Algebraic Signature

• Encoding data in servers
• Protection against incidental viewing in servers
• Fast manipulation of string
• Encoding form directly in servers
• The fastest technology in manipulation of
  characters.
• Prefix search
• Corruption protection ( future)
• Data Compression ( future)

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Applications

• Servers SDDS
• Data Grid
• P2P Systems
• XML data
• Search engine
• MSN ?

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Prototype SDDS 2005
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Problematic
No protection data

• - Data on clear viewing per on authorized
  administrator
• - Storage dump

Encoding\ Decoding of data by client

• Data encoded in servers
• Different possibilities of search.

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Data structure
Key Data
Non Key Data

• Encoding/decoding concerns non key data.
• Encoding/decoding is transparent for servers.
• Limit of 256B for data
• actually

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Search of string

• Aalgorithms Boyer Moore, Karp Rabin
• SDDS-2005
• No sent data to search.
• Sending signature
• Best confidentiality
• Encoding
• Pré- computed algebraic signatures

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Cumulative signature
Structure of Galois field GF(2f )
fgtgt1 symbols of size f8,16 primitive element
? algebraic signature (p1,p2,,pn)? pi ?i
Pre-computed signature piantilog (log pii)
Encoding pi pi pi-1 XOR pi
in-1
i0
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Cumulative signature
Comparison of signatures verification of
collision
Client
Décoding
Pré compute of signatures Gain of
search time
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Performances dEncodage / Décodage
Size of record Encoding time Decoding time Iinsertion time
100B 0.045ms 0.042ms 0.3ms
Fast Time encoding / decoding. Signatures pre
computed serach time reduced
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SDDS-2005String matching functions

• Prefix search
• String search
• Sent of signature size of data

• Longest Prefix match
• Longest common String
• Sent of data to comparison

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Cumulative signature
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Performance(cumulative signature)
Préfix Search
String match search
Longest Prefix Match
Search time in 2 servers comparison Search
time in only one server
Longest Common String
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Cumulative signature

• Reduction of search time
• -Existent Algorithms existents (30 algebraic
  signature, 5 Karp-Rabin, Size(Data) gt32B
• Non encoded data

New Search Functions
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SDDS-2005 Cumulative signatures

• Opérationnel Functions (2005)
• Prefix Search
• String matching
• Longest Prefix match
• Longest Common String

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Cumulative Signatures
Théory labour (2005) - Comparison with Karp
Rabin algorithm. Remaining work - Data gt
256B - Performance mesures - Amélioration of
signature calculation time (Horner scheme,
Broder table) -Data compression (prefix,
suffix, full )
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The endMerci Riad Mokadem