bitcoin’s transaction processing
DESCRIPTION
Bitcoin’s Transaction Processing. Yonatan Sompolinsky joint work with Aviv Zohar. Bitcoin. decentralized cryptocurrency. hard to get easy to pass no authority, no money printing pseudonymous relatively secure high transaction volume. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/1.jpg)
Bitcoin’s Transaction Processing
Yonatan Sompolinsky
joint work with Aviv Zohar
![Page 2: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/2.jpg)
Bitcoin
hard to get
easy to pass
no authority, no money printing
pseudonymous
relatively secure
? high transaction volume
decentralized cryptocurrency
current protocol: conflictghost protocol: in accord
![Page 3: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/3.jpg)
Transactions in Bitcoin
tx
tx
tx
tx
tx
tx
tx
tx
tx txtx
tx
txtx tx
Bob Calvin
? irreversible
tx’
tx’
tx’
tx’
tx’
tx’
![Page 4: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/4.jpg)
txs:
block #81 block #82 block #83
The Blockchain
txs: txs:
~ 10 min
• consistent
• grows in time
• kept locally at each node
Time
![Page 5: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/5.jpg)
A
B2
B1
maintain one main chain only
blocks discarded & txs cancelled
Conflicting blockchains
the”longest chain”
rule
delays => forks
Time
![Page 6: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/6.jpg)
Block tree vs Block chain
1
3
2
5
4 6
λ:= block creation rate =
6 per hour
β:= growth rate of main chain =
4 per hour
efficiency:= β/λ=4/6<1
Time
delays => forks =>
inefficiency
![Page 7: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/7.jpg)
Block size, Delay & Efficiency
analysis of data provided to us by Decker and Wattenhofer
λ = block creation rate
β = growth rate of main chain
0
𝛼𝑚𝑖𝑛
0.95 Efficiency =
0
Block Propagation Time
𝐵𝑙𝑜𝑐𝑘𝑆𝑖𝑧𝑒 (𝐾𝐵)Tim
e(s
ec
)
![Page 8: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/8.jpg)
Throughput (TPS)
Transactions Processed per Second =
(block size) X (growth rate of the main chain) efficiency
2000 1/600
TPS ~ 1736
TPS < 3.3why?
![Page 9: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/9.jpg)
Security - double spend attack
tx’
tx
Bob Calvin
tx
secret
tx
main chain
publish !
![Page 10: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/10.jpg)
Success of attack
• computational power needed to create blocks
• share of blocks proportional to fraction of
computational power
• an attacker with computational power will eventually
fail
• conversely, an attacker with will always succeed
• security threshold is thus
![Page 11: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/11.jpg)
Effect of increasing throughput
↑ efficiency↓
security ↓TPS ↑
delay ↑
![Page 12: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/12.jpg)
Security limitation on TPS
attacker computational power (fraction)
TPS
Bitcoin today: secure butlow throughput
high TPS: more bandwidth needed
secure TPS
vulnerable TPS
![Page 13: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/13.jpg)
Greedy Heaviest Observed Sub-Tree
longest chainefficiency ↓ security ↓
![Page 14: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/14.jpg)
Greedy Heaviest Observed Sub-Tree
B
C1
A
C2
C3
D1
D2
D3 E1
tx’
B tx
main chain according to “longest” rule
main chain according to “longest” rule
104
5
1
1
1
2
6
main chain according to “ghost”
Time
![Page 15: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/15.jpg)
GHOST throughput
• no security constraint
• hardware constraints, e.g., network congestion, limit the feasible TPS
• 8.5-fold increase of current bandwidth can withstandTPS = 2000
• in pipeline: improvement of ghost, same bandwidth more TPS
…
security
high transaction volume
![Page 16: Bitcoin’s Transaction Processing](https://reader036.vdocuments.site/reader036/viewer/2022062314/56814356550346895dafd4b7/html5/thumbnails/16.jpg)
https://eprint.iacr.org/2013/881.pdf