Information Propagation in the Bitcoin Network Christian Decker - PowerPoint PPT Presentation

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

What is Bitcoin?

What is Bitcoin? +

What is Bitcoin? = +

What’s it worth? USD / Bitcoin exchange price 300 250 150 $ /BTC 200 Price [USD] 150 100 50 0 0 1 1 1 2 2 2 3 3 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 t b n t b n t b n c e u O c e u O c e u O F J F J F J

What’s it worth? USD / Bitcoin exchange price 300 250 150 $ /BTC 200 Price [USD] 150 100 50 0 0 1 1 1 2 2 2 3 3 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 t b n t b n t b n c e u O c e u O c e u O F J F J F J

What’s it worth? USD / Bitcoin exchange price 300 250 150 $ /BTC 200 Price [USD] 150 100 50 0 0 1 1 1 2 2 2 3 3 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 t b n t b n t b n c e u O c e u O c e u O F J F J F J

What’s it worth? USD / Bitcoin exchange price 300 250 150 $ /BTC 200 Price [USD] 150 100 50 0 0 1 1 1 2 2 2 3 3 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 t b n t b n t b n c e u O c e u O c e u O F J F J F J

Why so popular? • Global • Fast • Irreversible • No intermediary • Anonymous

Bitcoin Basics

✠ Bitcoin basics

✠ Bitcoin basics TX TX” TX’

Bitcoin basics TX TX” ✠ TX’

✠ Bitcoin basics

✠ Bitcoin basics

Our Results

Propagation speed Block propagation 0.12 0.10 0.08 PDF 0.06 0.04 0.02 0.00 0 10 20 30 40 50 60 Time since first observation [s]

Propagation speed Block propagation 0.12 50th perc. 0.10 0.08 PDF 0.06 0.04 0.02 0.00 0 10 20 30 40 50 60 Time since first observation [s]

Propagation speed Block propagation 0.12 50th perc. 95th perc. 0.10 0.08 PDF 0.06 0.04 0.02 0.00 0 10 20 30 40 50 60 Time since first observation [s]

Propagation speed Block propagation 0.12 0.10 0.08 PDF 0.06 0.04 0.02 0.00 0 10 20 30 40 50 60 Time since first observation [s]

Information eclipsing

Information eclipsing

Information eclipsing

Information eclipsing

Blockchain Basics

The Blockchain Time

The Blockchain Time

The Blockchain Time

The Blockchain Time

Our Results

Blockchain Forks Blockchain forks 12 10 8 Forks 6 4 2 0 180000 182000 184000 186000 188000 190000 Blockchain Height

Blockchain Forks Blockchain forks 12 10 8 Forks 6 1.69% 4 2 0 180000 182000 184000 186000 188000 190000 Blockchain Height

Blockchain Forks: Model Probability of finding a block: P b = Pr [ X b < t + 1 | X b ≥ t ] ≈ 1 / 600

Blockchain Forks: Model Probability of finding a block: P b = Pr [ X b < t + 1 | X b ≥ t ] ≈ 1 / 600 Part of the network that may fork: f ( t ) = fraction of network knowing block at time t

Blockchain Forks: Model Probability of finding a block: P b = Pr [ X b < t + 1 | X b ≥ 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 � ∞ 0 (1 − f ( t )) dt P f = 1 − (1 − P b )

Blockchain Forks: Validating our Model P b = 1 / 633 . 68 � ∞ ¯ F = (1 − f ( t )) dt = 11 . 37 0 F = 1 . 78% ¯ P f = 1 − (1 − P b )

Pushing the protocol to its limits

Pushing the protocol to its limits block verification Node A a block inv t a d t e g Node B

Pushing the protocol to its limits block diff verification Node A getdata block inv Node B

Pushing the protocol to its limits getdata inv block diff verification Node A getdata block inv Node B

Did it work? Blockchain forks 12 10 8 Forks 6 1.69% 4 2 0 180000 182000 184000 186000 188000 190000 Blockchain Height

Did it work? Blockchain forks (influenced) 12 10 8 Forks 6 1.69% 4 0.78% 2 0 200000 202000 204000 206000 208000 210000 Blockchain Height

What does this mean?

What does this mean?

Block propagation 0.12 0.10 0.08 PDF 0.06 0.04 0.02 0.00 0 10 20 30 40 50 60 Time since first observation [s] Conclusion

Conclusion Block propagation 0.12 0.10 0.08 PDF 0.06 0.04 0.02 0.00 0 10 20 30 40 50 60 Time since first observation [s]

Conclusion Block propagation 0.12 0.10 0.08 PDF 0.06 0.04 0.02 0.00 0 10 20 30 40 50 60 Time since first observation [s]

Thank you, questions? Authors: Christian Decker Roger Wattenhofer ETH Zurich – Distributed Computing Group – www.disco.ethz.ch