Bitcoins Transaction Processing Yonatan Sompolinsky joint work with Aviv Zohar.
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Transcript of Bitcoins Transaction Processing Yonatan Sompolinsky joint work with Aviv Zohar.
![Page 1: Bitcoins Transaction Processing Yonatan Sompolinsky joint work with Aviv Zohar.](https://reader038.fdocuments.in/reader038/viewer/2022102923/5519fdac5503464c588b4ab9/html5/thumbnails/1.jpg)
Bitcoin’s Transaction Processing
Yonatan Sompolinsky
joint work with Aviv Zohar
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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
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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’
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txs:
block #81 block #82 block #83
The Blockchain
txs: txs:
~ 10 min
• consistent
• grows in time
• kept locally at each node
Time
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A
B2
B1
maintain one main chain only
blocks discarded & txs cancelled
Conflicting blockchains
the”longest chain”
rule
delays => forks
Time
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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
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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
)
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Throughput (TPS)
Transactions Processed per Second =
(block size) X (growth rate of the main chain) efficiency
2000 1/600
TPS ~ 1736
TPS < 3.3why?
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Security - double spend attack
tx’
tx
Bob Calvin
tx
secret
tx
main chain
publish !
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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
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Effect of increasing throughput
↑ efficiency↓
security ↓TPS ↑
delay ↑
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Security limitation on TPS
attacker computational power (fraction)
TPS
Bitcoin today: secure butlow throughput
high TPS: more bandwidth needed
secure TPS
vulnerable TPS
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Greedy Heaviest Observed Sub-Tree
longest chainefficiency ↓ security ↓
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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
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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
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https://eprint.iacr.org/2013/881.pdf