DBFS - ElixirConf EU 2018 (Lightning Talk)

My lightning talk about building a naive blockchain-based file storage in Elixir and React, with scalability and distribution in mind.

Transcript

1. BLOCKCHAIN BASED
   FILE STORAGE
   

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2. SHEHARYAR NASEER
   sheharyarn shyr.io
   

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3. DIDN'T HODL
   

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4. blockchain
   noun /ˈbläkˌCHān/
   A decentralized, distributed digital ledger that is
   used to record transactions across many computers
   so that the record cannot be altered retroactively
   without the alteration of all subsequent blocks [...]
   

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5. BLOCK 5
   Data:
   Timestamp:
   Previous:
   Current:
   34k0scf
   2018-01-05 13:24:56
   3662c6f8dc7b519123c
   f9d644657c3d7c80a6f
   rth760ls
   2018-01-07 18:43:12
   f9d644657c3d7c80a6f
   bbd658cb57bb0d2138
   BLOCK 6
   Data:
   Timestamp:
   Previous:
   Current:
   qnb49f0
   2018-01-08 06:11:34
   bbd658cb57bb0d2138
   8327ed293f7834c6572
   BLOCK 7
   Data:
   Timestamp:
   Previous:
   Current:
   

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6. ARCHITECTURE
   – Blockchain Structure
   – File Storage
   – Cryptography
   – Synchronization
   – Client API
   

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7. BLOCKCHAIN
   %Block{
   type: ...,
   timestamp: ...,
   data: %{
   file_name: ..., file_hash: ..., file_key: ...,
   },
   prev: ...,
   creator: ...,
   hash: ...,
   signature: ...
   }
   

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8. FILE STORAGE
   – Nothing fancy
   – Directly on the disk
   – Encrypted
   – Block hash as identifier
   

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9. CRYPTOGRAPHY
   – Public Key: RSA
   – Symmetric: AES
   

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10. CRYPTOGRAPHY
    – Public Key: RSA
    – Symmetric: AES
    – Hashing: SHA256
    – Encoding: Base64
    

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11. SYNCHRONIZATION
    – Erlang VM: Easy Distribution
    – Consensus: Raft
    – Elect 'leader'
    – Use it as a reference
    

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12. SYNCHRONIZATION
    – Find where the chain diverges
    – Send the succeeding block
    def sync_next(leader, hash) do
    %{block: block, file: file} =
    :rpc.call(leader, Blockchain, :next, [hash])
    Blockchain.insert(block, file)
    end
    

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13. CLIENT API
    – Phoenix
    – List, Upload, Download
    – Ecto Validations
    – Status Channel
    

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14. CLIENT API
    – React
    – Encrypt the file on client-side
    – Form the block
    – Sign it and calculate hash
    – Insert it into the blockchain
    

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15. DEMO
    

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16. OUTRO
    Elixir App: to.shyr.io/dbfs
    React App: to.shyr.io/dbfs-web
    shyr.io
    ~@shyr.io
    sheharyarn
    

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