Proof of Storage Time: Efficiently Checking Continuous Data - - PowerPoint PPT Presentation

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Proof of Storage Time: Efficiently Checking Continuous Data - - PowerPoint PPT Presentation

Oct 15, 2023 247 likes •568 views

Proof of Storage Time: Efficiently Checking Continuous Data Availability Gi Giuseppe At Ateniese Lo Long Chen hen Stevens Institute of Technology New Jersey Institute of Technology Mo Moham ammad ad Et Etemad ad Qi Qiang Ta Tang

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Proof of Storage Time: Efficiently Checking Continuous Data Availability

Gi Giuseppe At Ateniese Stevens Institute of Technology Mo Moham ammad ad Et Etemad ad Stevens Institute of Technology Lo Long Chen hen New Jersey Institute of Technology Qi Qiang Ta Tang New Jersey Institute of Technology

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Outsourced Storage is a common practice Backup Data sharing Saving Cost

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Example Case

A hospital stores medical imaging data on the cloud Surgeons will consult these data during an emergency surgery A brief downtime will cause a serious medical accident! Co Continuous da data av availability is is cr cruci cial

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Mission and Business Critical Applications

Brief downtime may lead to serious negative consequences

  • Lost of productivity
  • Financial pain
  • Damages to the business’ reputation
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SLIDE 5

Threats to Continuous Availability

Equipment failures Power outrages Malicious attackers

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Cost of Continuous Availability

More replications More hardware and software components More complex administration

Co Continuous av availability mea means a hi high price ce !

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Verify Continuous Availability

A dishonest server would provide an inferior service The client who paid a high price must verify the continuous availability

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SLIDE 8

Decentralized Storage Market

File Data Owner Blockchain

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Decentralized Storage Market

File Data Owner Server

!

  • ! must be succinct
  • Verification must be cheap

Smart Contract

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Proof of Storage- time

Definition Construction Instantiation

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Proof of Storage- time

Construction Instantiation

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PoSt Framework

Store Challenge Response

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Security Definition

Proof of Retrievability

Goa

  • al: Verify data availability

Securi urity ty: Extractability

Proof of Storage-time

Goa

  • al: Verify continuous availability

Securi urity ty: Continuous extractability

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Continuous Extractability

Stop at time point ! Record the current state in the memory Adversary Extractor File

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Proof of Storage- time

Definition Instantiation

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Naïve Attempts

  • A challenge and response protocol
  • Only certify availability at the time a valid proof is processed

Proof of Retrievability

  • Inefficient communication and verification
  • The client needs to be always online

Frequent PoR

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Unsuccessful Attempts

Send PoR challenges in advance

  • The prover may compute all PORs rapidly

and discard the data

Send PoR challenges in the end

  • The prover could keep data offline and

retrieve them at the last moment

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Filecoin’s proposal

  • 1. Send PoR challenge !"
  • 2. Compute the PoR proof #"
  • 3. Let !$ = &'(ℎ #"
  • 4. Compute the PoR proof #$
  • 5. ……
  • 6. Send back all !* and #*

Problem: :

  • No concrete delay guarantee
  • Verification is inefficient
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Verifiable Delay Function

! " = $

ØTo compute $ for honest guys takes time almost % ØMalicious guy, even with parallel ability, can not get the result within time % ØAnyone can efficiently verify the correctness

  • f the evaluation with a proof &

&

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Warm-up Construction

1. Given a PoR challenge !" 2. Generate the PoR #" 3. Compute !$, &$ = ()*(#") 4. Generates the PoR #$ 5. Etc. 6. Output all !-, #-, &-

!" #" VDF !$ #$

PoSt Proof

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Problem

  • The proof size is too large
  • Verification is inefficient
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Trapdoor Delay Function

! " = $

ØTo compute $ for honest guys takes time almost % ØMalicious guy can not get $ within time % even with parallel computing

! ", '()*+,,( = $

ØAnyone with trapdoor can compute $ within time significantly smaller than %

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Verification: !", $", !%, $%, … = !", $", !%, $%, … ()*ℎ(!", $", !%, $%, … ) = ()*ℎ(!", $", !%, $%, … )

Main Construction

Aggregation

!" $"

Delay

!% $% !" $"

Without Delay

!% $%

Public Validation

.)/ = ()*ℎ(()*ℎ !", $", !%, $%, … )

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Decentralized Storage Market

File Smart Contract Data Owner Server !"# ℎ Verify !"# = &"'ℎ(ℎ)

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Proof of Storage- time

Definition Construction

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Efficiency of Each Procedure Ver erification

  • n

Extremely efficient

Proof

  • of

Inherent cost

Stor

  • ring

Main left concern

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Storing Procedure Optimization

Adopting Hash based PoRs Precomputation Accelerate the PoR by Parallel Computation Others…

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Storing Benchmark

50 100 150 200 250 30 60 90 120 150 Setup time (min) Data available time (day) 64 MB 128 MB 192 MB 256 MB

Hourly data check up

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Summary

PoSt can verify continuous data availability PoSt can be used to realize the decentralized storage market Future work

  • Optimization the storing procedure
  • Make it stateless
  • Achieve public verifiable
  • More applications
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Thank you for attention

Gi Gius useppe At Ateniese Stevens Institute of Technology Mo Moha hammad Et Etemad Stevens Institute of Technology Long C Chen New Jersey Institute of Technology Qi Qiang Ta Tang New Jersey Institute of Technology