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Alois Cochard's Blog

AloÏs Cochard is a developer in a business software company. He started learning Java at 12 and spends his free time to develop network security tools and messaging software. During his study he explored GUI development creating an open-source alternate UI for windows (developed with an L5G language allowed for focusing on the GUI). His current project is UniNet, an open source project created to achieve a freedom decentralized area used by people to share data and CPU power.

Networking: Ensure data integrity in a decentralized storage system

Posted by alois on January 27, 2009 at 12:57 AM | Permalink | Comments (1)

Introduction
I'm actually developing on my free time a decentralized computing platform in java, I'm in the early stage, defining concepts and building the foundation.
This platform is target to be available to anyone connected to internet, so data integrity must be granted to avoid corruption of data from someone else, I gonna describe the concept I created to avoid any corruption of data in a high decentralized storage system.

Definition
The decentralized platform consist of (highly simplified):

Network service to handle data request (from remote peer or from local clients)
Storage service to store data and data checksum
Communication service to handle request/respond between peers

The source identifier, is the peer identifier of the peer who provided the data.

Integrity checking scenario
Network service receive data request:

ask storage if data exist (using data id)

if not, request data from other peers
save data inside storage with source identifier

compute data checksum
request data checksum from other peers

if data cheksum come from same peer as data, request data cheksum from other peer

compare both data checksums

if checksums are different:

increment integrity failure counter

if integrity failure counter exceed defineed limit

delete data and data checksum from storage

exit scenario without returning data

if checksums are equal:

reset integrity failure counter

save data checksum with source identifier inside storage
return data

Conclusion
Please feel free to comment it, especially if you know better solution or any software who have implemented a such concept efficiently.

UniNet experimental project was close, you can find informations about my new project here.

Alois Cochard's Blog

Networking: Ensure data integrity in a decentralized storage system

January 2009

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