Stressing Out: Bitcoin Stress Tes2ng Khaled Baqer, Danny Yuxing - - PowerPoint PPT Presentation

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Stressing Out: Bitcoin Stress Tes2ng Khaled Baqer, Danny Yuxing - - PowerPoint PPT Presentation

Dec 18, 2023 138 likes •278 views

Stressing Out: Bitcoin Stress Tes2ng Khaled Baqer, Danny Yuxing Huang, Damon McCoy and Nick Weaver (given by Ross Anderson) Overview Spam aNack on Bitcoin (July 2015) Importance: block size debate! At present you can bring down

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Stressing Out: Bitcoin “Stress Tes2ng”

Khaled Baqer, Danny Yuxing Huang, Damon McCoy and Nick Weaver (given by Ross Anderson)

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Overview

  • Spam aNack on Bitcoin (July 2015)
  • Importance: block size debate! At present you

can bring down Bitcoin for $50k

  • Goal here: highlight spam mo2fs, inves2gate

impact, analyse security economics (fee income increase, cost of spam campaign)

  • Used a clustering method to group

transac2ons and find paNerns

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Bitcoin spam

  • Fan-in: Transac2ons that absorb a lot of inputs

reduce the unspent transac2on output (UTXO) set but s2ll occupy substan2al space in the blocks

  • Fan-out: Transac2ons that split a few inputs into

many outputs occupy space in blocks and also increase the UTXO set (Mempool impact)

  • Dust output: “Dust” outputs convey a trivial

amount of value but occupy the same amount of resources in the Bitcoin network

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Spam campaign (July 2015)

  • Someone said, ‘stress tes2ng Bitcoin network’
  • Mo2va2on (?): show Bitcoin is vulnerable to

DoS, and get support to raise the block size

  • DoS: send transac2ons with higher fees to

deplete space in blocks

  • Spam also uses many similar transac2ons to

have a significant impact on the network

  • But what does spam look like?
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SLIDE 5

k-means Clustering

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SLIDE 6

k-means Clustering (II)

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Impact on Bitcoin:

The number of transac2ons per day in the blockchain

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Impact on Bitcoin (II):

The average number of unconfirmed transac2ons

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Impact on Bitcoin (III):

The total amount of transac2on fees every day

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Impact on Bitcoin (IV):

Average transac2on delay

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Impact on Bitcoin (V):

Average transac2on fees per transac2on per day (normalized)

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Summary of results

(10-day spam campaign)

  • 385,256 (23.41%) out of 1,645,667 total

Bitcoin transac2ons were spam

  • Spam increased average fees by 51% (from 45

to 68 Satoshis/byte)

  • Spam increased processing delay by 7 2mes

(from 0.33 to 2.67 hours)

  • Cost of this aNack on Bitcoin: $49K, about half

being to pay higher fees

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SLIDE 13

Ques2ons?

  • If skype doesn’t work,. email hard ques2ons

to khaled.baqer@cl.cam.ac.uk (who could not get a visa processed in 2me)

  • Further possible discussions for the barbecue:

sovereign risk and other emergent problems

  • f governance