Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network...

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Information Propagation in the Bitcoin Network Christian Decker ETH Zurich – Distributed Computing Group – www.disco.ethz.ch

Transcript of Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network...

Page 1: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Information Propagationin the Bitcoin Network

Christian Decker

ETH Zurich – Distributed Computing Group – www.disco.ethz.ch

Page 2: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

What is Bitcoin?

+ =

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What is Bitcoin?

+

=

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What is Bitcoin?

+ =

Page 5: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

What’s it worth?

Oct 2010

Feb 2011

Jun 2011

Oct 2011

Feb 2012

Jun 2012

Oct 2012

Feb 2013

Jun 20130

50

100

150

200

250

300Pri

ce [

USD

]

USD / Bitcoin exchange price

150$/BTC

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What’s it worth?

Oct 2010

Feb 2011

Jun 2011

Oct 2011

Feb 2012

Jun 2012

Oct 2012

Feb 2013

Jun 20130

50

100

150

200

250

300Pri

ce [

USD

]

USD / Bitcoin exchange price

150$/BTC

Page 7: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

What’s it worth?

Oct 2010

Feb 2011

Jun 2011

Oct 2011

Feb 2012

Jun 2012

Oct 2012

Feb 2013

Jun 20130

50

100

150

200

250

300Pri

ce [

USD

]

USD / Bitcoin exchange price

150$/BTC

Page 8: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

What’s it worth?

Oct 2010

Feb 2011

Jun 2011

Oct 2011

Feb 2012

Jun 2012

Oct 2012

Feb 2013

Jun 20130

50

100

150

200

250

300Pri

ce [

USD

]

USD / Bitcoin exchange price

150$/BTC

Page 9: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Why so popular?

• Global

• Fast

• Irreversible

• No intermediary

• Anonymous

Page 10: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Bitcoin Basics

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Bitcoin basics

TX

TX’

TX”

Page 12: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Bitcoin basics

TX

TX’

TX”

Page 13: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Bitcoin basics

TX

TX’

TX”

Page 14: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Bitcoin basics

TX

TX’

TX”

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Bitcoin basics

TX

TX’

TX”

Page 16: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Our Results

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Propagation speed

0 10 20 30 40 50 60Time since first observation [s]

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PDF

Block propagation

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Propagation speed

0 10 20 30 40 50 60Time since first observation [s]

0.00

0.02

0.04

0.06

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PDF

Block propagation

50thp

erc.

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Propagation speed

0 10 20 30 40 50 60Time since first observation [s]

0.00

0.02

0.04

0.06

0.08

0.10

0.12

PDF

Block propagation

50thp

erc.

95thp

erc.

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Propagation speed

0 10 20 30 40 50 60Time since first observation [s]

0.00

0.02

0.04

0.06

0.08

0.10

0.12

PDF

Block propagation

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Information eclipsing

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Information eclipsing

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Information eclipsing

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Information eclipsing

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Blockchain Basics

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The Blockchain

Time

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The Blockchain

Time

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The Blockchain

Time

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The Blockchain

Time

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Our Results

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Blockchain Forks

180000 182000 184000 186000 188000 190000Blockchain Height

0

2

4

6

8

10

12

Fork

sBlockchain forks

1.69%

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Blockchain Forks

180000 182000 184000 186000 188000 190000Blockchain Height

0

2

4

6

8

10

12

Fork

sBlockchain forks

1.69%

Page 33: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Blockchain Forks: Model

Probability of finding a block:

Pb = Pr [Xb < t + 1|Xb ≥ t] ≈ 1/600

Part of the network that may fork:

f (t) = fraction of network knowing block at time t

Probability of a blockchain fork

Pf = 1− (1− Pb)∫∞

0 (1−f (t))dt

Page 34: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Blockchain Forks: Model

Probability of finding a block:

Pb = Pr [Xb < t + 1|Xb ≥ t] ≈ 1/600

Part of the network that may fork:

f (t) = fraction of network knowing block at time t

Probability of a blockchain fork

Pf = 1− (1− Pb)∫∞

0 (1−f (t))dt

Page 35: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Blockchain Forks: Model

Probability of finding a block:

Pb = Pr [Xb < t + 1|Xb ≥ t] ≈ 1/600

Part of the network that may fork:

f (t) = fraction of network knowing block at time t

Probability of a blockchain fork

Pf = 1− (1− Pb)∫∞

0 (1−f (t))dt

Page 36: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Blockchain Forks: Validating our Model

Pb = 1/633.68

F̄ =

∫ ∞0

(1− f (t))dt = 11.37

Pf = 1− (1− Pb)F̄ = 1.78%

Page 37: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Pushing the protocol to its limits

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Pushing the protocol to its limits

Node A

Node B

block

verification

inv

getd

ata block

diff verification

inv

getd

ata block

diff verification

inv

getd

ata

inv

getd

ata block

Page 39: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Pushing the protocol to its limits

Node A

Node B

block

verification

inv

getd

ata block

diff verification

inv

getd

ata block

diff verification

inv

getd

ata

inv

getd

ata block

Page 40: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Pushing the protocol to its limits

Node A

Node B

block

verification

inv

getd

ata block

diff verification

inv

getd

ata block

diff verification

inv

getd

ata

inv

getd

ata block

Page 41: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Did it work?

180000 182000 184000 186000 188000 190000Blockchain Height

0

2

4

6

8

10

12

Fork

sBlockchain forks

1.69%

Page 42: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Did it work?

200000 202000 204000 206000 208000 210000Blockchain Height

0

2

4

6

8

10

12

Fork

sBlockchain forks (influenced)

1.69%

0.78%

Page 43: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

What does this mean?

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What does this mean?

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Conclusion

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Block propagation

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Conclusion

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Conclusion

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Block propagation

Page 48: Information Propagation in the Bitcoin Network · Information Propagation in the Bitcoin Network ... Oct 2010 Feb 2011 Jun 2011 Oct 2011 Feb 2012 Jun 2012 Oct 2012 Feb 2013 Jun 2013

Thank you, questions?

Authors:Christian DeckerRoger Wattenhofer

ETH Zurich – Distributed Computing Group – www.disco.ethz.ch