Auction-based Model of BitTorrent Seminar in Distributed Computing - - PowerPoint PPT Presentation

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Auction-based Model of BitTorrent Seminar in Distributed Computing - - PowerPoint PPT Presentation

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Auction-based Model of BitTorrent Seminar in Distributed Computing 2010 ETH Zurich Yu Li What is BitTorrent How to download using BitTorrent STEP 1: Select Torrent File STEP 1: Select STEP 1: Select STEP 1: Select Torrent File Torrent

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SLIDE 1

Auction-based Model of BitTorrent

Seminar in Distributed Computing 2010 ETH Zurich Yu Li

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SLIDE 2

What is BitTorrent

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SLIDE 3

How to download using BitTorrent

STEP 1: Select STEP 1: Select STEP 1: Select STEP 1: Select Torrent File Torrent File Torrent File Torrent File STEP 2: Download Torrent STEP 2: Download Torrent STEP 2: Download Torrent STEP 2: Download Torrent

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SLIDE 4

How to download using BitTorrent

STEP 3: Configuration STEP 3: Configuration STEP 3: Configuration STEP 3: Configuration STEP 4: Download File STEP 4: Download File STEP 4: Download File STEP 4: Download File

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SLIDE 5

Downloading procedure

  • Individuals View

– Seed – Leecher

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SLIDE 6

Downloading procedure

  • System View

– I upload and download at the same time

… … Me

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SLIDE 7

Auction-based Model

[D. Levin, K. LaCurts, 2008] "BitTorrent is an Auction: Analyzing and Improving BitTorrent’s Incentives"

(Q1) Do I upload to everyone?

… … Me … … Me

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SLIDE 8

Auction-based Model

(Q2) Do I treat every peer equally?

… … Me (6Mbps) … … Me (6Mbps) 2 1 4 2 6 3 2 2 4 2 6 2

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SLIDE 9

Auction-based Model

(Q3) Do I ignore others?

… … Me (6Mbps) … … Me (6Mbps) 2 2 4 2 6 2 2

1.5 1.5 1.5 1.5 4 1.5 1.5 1.5 1.5 6 1.5 1.5 1.5 1.5

0.1 0.2 0.1 0.2

1.5 1.5 1.5 1.5

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SLIDE 10

Auction-based Model

  • Bids are uploads of round n-1
  • Auction clearing

Me (Bandwidth W) 18 12 3 2 1 Round n-1 Round n

18 18 18 18

Me (Bandwidth W)

12 12 12 12

3 3 3 3 2 2 2 2 1 1 1 1 W/S Highest S-1 1 random peer W/S W/S Select S peers (S=4) W/S

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SLIDE 11

Sybil Attack

  • Normal Bidder

3 3 3 3

12 12 12 12 18 18 18 18

1 1 1 1 2 2 2 2 18Mbps 18Mbps 18Mbps 18Mbps Auctioneer (Me) provides 72Mbps bandwidth in total “Red” bidder gets 18Mbps n-1 round n round

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SLIDE 12

Sybil Attack

  • Selfish Bidder

3 3 3 3 4 4 4 4

18 18 18 18

1 1 1 1 2 2 2 2 4 4 4 4 4 4 4 4

12 12 12 12

“Red” bidder sybil gets 2×18Mbps n-1 round n round 18Mbps 18Mbps 18Mbps 18Mbps Auctioneer (Me) provides 72Mbps bandwidth in total

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SLIDE 13

Review of Question 2

  • (Q2) Do I treat every peer equally?

… … Me (6Mbps) … … Me (6Mbps) 2 1 4 2 6 3 2 2 4 2 6 2

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SLIDE 14

Countermeasure: Proportional share auction

  • Proportional share

3 3 3 3

12 12 12 12 18 18 18 18

1 1 1 1 2 2 2 2 36Mbps 24Mbps

6

4 2 n-1 round n round “Red” bidder gets 24Mbps

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SLIDE 15

Countermeasure: Proportional share auction

  • Sybil attack resilient

36Mbps

8Mbps 8Mbps 8Mbps 8Mbps

6

4 2 n-1 round n round 3 3 3 3 4 4 4 4

18 18 18 18

1 1 1 1 2 2 2 2 4 4 4 4 4 4 4 4

12 12 12 12

8Mbps 8Mbps 8Mbps 8Mbps 8Mbps 8Mbps 8Mbps 8Mbps

“Red” bidder sybil gets 3×8=24Mbps

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SLIDE 16

Comparison of Auction-based &Propshare

24 Mbps 24 Mbps Propshare 2×18 Mbps 18 Mbps Standard Bittorrent Selfish client (using sybil) Normal client

  • Propshare is Sybil proof
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SLIDE 17
  • Which one is better for me?

Under-reporting

Me A

X Y

B

X Y X Y

Me A

X Y

B

X Y X Y

Me A

X Y

B

X Y X Y

Me A

X Y

B

X Y X Y

Me A

X Y

B

X Y X Y

X X X X X X X X

Under- reporting

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SLIDE 18

Under-reporting

  • Under-reporting algorithm

– Run algr. when peer is about to lose interest. – Determine the most common piece among available

X Y Z X Y Z X Y Z X Y Z Tom Peer 1 Peer 2 Peer 3 X Y Z Alice X Y Z X Y Z X Y Z Peer 1 Peer 2 Peer 3 X Y Z Tom X Y Z Alice

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SLIDE 19

Under-reporting

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SLIDE 20

Countermeasure: Gossiping

Me

X X X X Y Y Y Y Z Z Z Z Z Z Z Z

X X X X Y Y Y Y Z Z Z Z

Costs overhead

B A

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SLIDE 21

Countermeasure: TrInc

[D.Levin, J.R. Douceur 2009] "TrInc: Small Trusted Hardware for Large Distributed Systems"

  • TrInc (Trusted Incrementer)

– Prevents lying – Decreases overhead

  • TPM (Trusted Platform

Module) by Intel

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SLIDE 22

Countermeasure: TrInc

  • System equipped with TrInc
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SLIDE 23

Countermeasure: TrInc

  • Individual equipped with TrInc
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SLIDE 24

Countermeasure: TrInc

  • How does TrInc work?

Old Old Old Old Counter Counter Counter Counter Value Value Value Value New New New New Counter Counter Counter Counter Value Value Value Value New Counter Value New Counter Value New Counter Value New Counter Value

Encryption Encryption Encryption Encryption

BitField BitField BitField BitField BitField BitField BitField BitField + New Counter Value + Old Counter Value + New Counter Value + Old Counter Value + New Counter Value + Old Counter Value + New Counter Value + Old Counter Value

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SLIDE 25

Countermeasure: TrInc

  • Input

– New Counter Value – BitField

  • Output

– Attestation

  • Sample Output

B′

A B C

… … … …

D Y Z

B

A B C

… … … …

D Y Z

  • B′

A B C D E F G

34

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SLIDE 26

Countermeasure

Me

X X X X Y Y Y Y Z Z Z Z Z Z Z Z

X X X X Y Y Y Y Z Z Z Z

B A

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SLIDE 27

Countermeasure: TrInc

X

2 3

Y Z T X

1 2

Y Z T X

0 1

Y Z T

X Y Z

X

0 1

Y Z T X

1 2

Y Z T X

2 3

Y Z T

Bitfield Request Piece Providing Piece Providing Piece Providing Nonce

X

2 3

Y Z T

3 3 Nonce 3 3 Nonce Me A B C D

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SLIDE 28

Countermeasure: TrInc

  • Individual equipped with TrInc
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SLIDE 29
  • Auction-based Model
  • TrInc
  • Q & A