How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via...
Transcript of How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via...
![Page 1: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/1.jpg)
How to Mimic Nakamoto’s Design via Proof-of-Stake
Hong-Sheng ZhouVirginia Commonwealth University
Fractal Platform
Jonathan Katz University of Maryland
Fractal Platform
Joint work with
Lei Fan Shanghai Jiaotong University
Fractal Platform
FRACTAL
![Page 2: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/2.jpg)
Outline • Why mimic Nakamoto’s design
• How to mimic
• Decoupling consensus & data distribution
![Page 3: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/3.jpg)
Why Mimic Nakamoto’s Design
![Page 4: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/4.jpg)
H( context, payload, solution ) < Tcontext = pointer to the last block in the longest chain
payload = valid TXs from users/networksolution = nonce
Nakamoto’s designConsensus via “Competition”
Proof of work puzzle
![Page 5: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/5.jpg)
Nakamoto’s design
From Garay et al, Eurocrypt 2015
![Page 6: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/6.jpg)
1. Large-scale
• low communication complexity
• local computing; non-interactive
2. Open: Easy to join/leave
3. Strong security
• adaptive security without assuming secure erasure
• next-block generator unpredictable
4. no fancy crypto tools used; core-chain using only standard hash
Nakamoto’s design
![Page 7: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/7.jpg)
• Consensus via “Competition” Nakamoto’s design; known since 2008 >10,000 nodes; very inclusive and trustworthy
• Consensus via “Discussions” Byzantine Fault Tolerance (BFT); known since 1980s< hundreds of nodes; not inclusive
• Large scale BFT-like protocols have never been stress-tested in real world, unlike Bitcoin, Ethereum
Why Mimic Nakamoto’s design
![Page 8: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/8.jpg)
Why Mimic Nakamoto’s Designvia Proof of Stake
![Page 9: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/9.jpg)
very secure ==> issues
1. Large-scale + 2. Open—> (ideally) very difficult to control the majority of the mining power==> small numbers of BIG miners dominate the system
Nakamoto’s design facing issues
![Page 10: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/10.jpg)
issue #1: mining centralization Bitcoin original vision: based on commodity machines, one CPU one vote
Today:Big mining pools dominate the system 80% mining power is in China
not very trustworthy
![Page 11: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/11.jpg)
very secure ==> issues
1. Large-scale + 2. Open—> (ideally) very difficult to control the majority of the miners==> small numbers of BIG miners dominate the system ==> huge waste of computing resources including electricity & hardware; small number of players dominate the system
Nakamoto’s design facing issues
![Page 12: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/12.jpg)
issue #2: energy consumption
https://digiconomist.net/bitcoin-energy-consumption
Is energy consumption a necessary? NO!!!
![Page 13: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/13.jpg)
Hardware manufacturers have BIG voices
Not inclusive
issue #3: dedicated hardware
![Page 14: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/14.jpg)
How to Mimic Nakamoto’s Design via Proof of Stake
![Page 15: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/15.jpg)
via trusted hardware / beacon
• single point of failure;
Conventional MPC/BFT like protocols
• high communication complexity; small size network; e.g., TenderMint, Ouroboros, DPoS
Bitcoin like efforts (based on hash inequality)
• NXT, SnowWhite: new players cannot join the system securely; not adaptively secure
• The closest work: Ouroboros Praos/Geneses Praos (concurrent work): new players cannot join the system securely; their follow-up Ouroboros Geneses: fixed this issue
Hybrid (hash inequality + BFT)
• Algorand: non local computing; more complex; historically no known such protocols have been stress-tested in the real world
… it is a non-trivial task
![Page 16: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/16.jpg)
via trusted hardware / beacon
• single point of failure;
Conventional MPC/BFT like protocols
• high communication complexity; small size network; e.g., TenderMint, Ouroboros, DPoS
Bitcoin like efforts (based on hash inequality)
• NXT, SnowWhite: new players cannot join the system securely; not adaptively secure
• The closest work: Ouroboros Praos/Geneses Praos (concurrent work): new players cannot join the system securely; their follow-up Ouroboros Geneses: fixed this issue
Hybrid (hash inequality + BFT)
• Algorand: non local computing; more complex; historically no known such protocols have been stress-tested in the real world
… it is a non-trivial task
![Page 17: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/17.jpg)
via trusted hardware / beacon
• single point of failure;
Conventional MPC/BFT like protocols
• high communication complexity; small size network; e.g., TenderMint, Ouroboros, DPoS
Bitcoin like efforts (based on hash inequality)
• NXT, SnowWhite: new players cannot join the system securely; not adaptively secure
• The closest work: Ouroboros Praos/Geneses Praos (concurrent work): new players cannot join the system securely; their follow-up Ouroboros Geneses: fixed this issue Comparison with ours: very different design; ours has faster confirmation time, and more flexible joining, than Praos/Geneses
Hybrid (hash inequality + BFT)
• Algorand: non local computing; more complex; historically no known such protocols have been stress-tested in the real world
… it is a non-trivial task
![Page 18: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/18.jpg)
How to Mimic Nakamoto’s Design via Proof of Stake
Step 1 defending against restricted adversaries
![Page 19: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/19.jpg)
• Proof-of-work core-chain (without payload) H( context, solution ) < T context = the pointer to the latest block in the longest chain solution = nonce solution without “structure”
• Proof-of-stake core-chain (without payload) H( context, round, solution ) < T context = the pointer to the latest block in the longest chain solution = <PK, σ> σ = Sign(SK, context, round) solution with “structure”
Step 1
search version vs decision version
![Page 20: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/20.jpg)
key modifications: round is used; unique signature is used.
Proof of stake core-chain, basic version
Step 1
![Page 21: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/21.jpg)
Unique signaturePublic info
Step 1
Proof of stake core-chain, basic version
This basic version is already nice in the sense that if the adversary is restricted to extend only one position, then the blockchain is secure
![Page 22: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/22.jpg)
How to Mimic Nakamoto’s Design via Proof of Stake
Step 2 defending against general adversaries
![Page 23: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/23.jpg)
Step 2In the basic version:
• Honest players extend one position (i.e., the latest block of the longest chain)
• The adversary is restricted, extending one position
In the reality
• The adversary extends multiple positions —> this is equivalent to amplifying the adversary’s stake —> known as “nothing at stake” attacks
![Page 24: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/24.jpg)
Step 2
The mining power can be amplified if players make attempts to extend multiple positions
• Folklore: amplification ratio >1
• Our main discovery: for carefully designed protocol, e.g., the basic version, amplification ratio is upper bounded !
![Page 25: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/25.jpg)
Step 2• main discovery:
amplification ratio is upper bounded !
• amplification ratio < e (i.e., 2.718)
• amplification ratio for 2-greedy is 2.1 We will define 2-greedy very soon
![Page 26: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/26.jpg)
Step 2• main discovery:
amplification ratio is upper bounded !
• amplification ratio < e (i.e., 2.718)
• amplification ratio for 2-greedy is 2.1
• another discovery:using “nothing at stake” to defend against “nothing at stake” attacks
generalgeneral
basicbasicbasic
2-greedy
![Page 27: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/27.jpg)
Greedy strategies
1-greedy
1. identify the longest chain 2. distance to the longest chain 3. length
De�nition 4.3 (Distance-greedy strategy). Consider a blockchain protocol execution. Let P be a player of theprotocol execution, and T be a tree which consists of chains with the same genesis block, in player P’s local view.Let Cbest be the longest chain at round r, where ` = len(Cbest). Consider parameters D and F. De�ne a chain setCbest as
Cbest = {C : distance(C ! Cbest) D, len(C) � `� F}
We say the player is (D, F)-distance-greedy if, for all r, the player makes a�empts to extend all chains C 2 Cbest.Remark 4.4. For simplicity, in the remaining of this section, we set F := D + 1, and call the above strategy,D-distance-greedy strategy for short. In Figure 6 and 7, pictorial illustration for 1-distance-greedy and 2-distance-greedy strategies can be found respectively.
Figure 6: 1-distance-greedy Figure 7: 2-distance-greedy
Adversarial strategies: full-greedy and general-greedy Nowwe turn to consider the adversarial strate-gies. An adversary may consider di�erent strategies to break the security of the blockchain system. For ex-ample, a restricted adversary may follow the full-greedy strategy to extend the all chain; here the full-greedystrategy is essentially the `-distance-greedy where ` is the length of the longest chain.
A more powerful adversarial strategy is called general-greedy strategy: instead of playing the full-greedystrategy to extend all chains, the adversary may treat the chains di�erently. �e adversary may extend thechains in an arbitrary manner; for example, the adversary may not extend the relatively longer chains, butthe shorter ones. We note that, a protocol secure against the full-greedy adversary may not be secure in thepresence of a general-greedy adversary. More discussions can be found in Appendix C.
Stake ampli�cation ratio As mentioned, when a player follows a distance-greedy strategy, he may extendthe chains faster. Next, we introduce ampli�cation ratio.De�nition 4.5 (Ampli�cation ratio). Consider a PoS blockchain protocol. LetN0 be the average increased lengthof the longest chain that extended by a group of players P, follow the 0-distance-greedy strategy. Let ND be theaverage increased length of the longest chain that extended by the same group of players P, follow the D-distance-greedy strategy. We de�ne the ampli�cation ratio for following the D-distance-greedy strategy as A�D =
NDN0
4.2 �e modi�ed core-chain protocol ⇧core�
Next, we present a new core-chain protocol ⇧core� with the goal of defending against adversaries who playgeneral-greedy strategies. �is new protocol is based on the core-chain protocol ⇧core in Section 3 but nowthe players follow the D-distance-greedy strategy. Details can be found in Figure 8.
We note that, the subroutine BestCore in the previous protocol, has also been modi�ed into subroutineD-BestCore�; now the modi�ed subroutine D-BestCore�, instead of returning the single longest chain, will
19
![Page 28: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/28.jpg)
Greedy strategies
1-greedy 2-greedy
![Page 29: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/29.jpg)
Step 2
Proof of stake core-chain, 2-greedy version
We can prove that if the honest players control more than 57% stake, then the 2-greedy version is secure
We can prove that if the honest players control more than 73% stake, then the basic version is secure
![Page 30: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/30.jpg)
How to Mimic Nakamoto’s Design via Proof of Stake
Next steps
![Page 31: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/31.jpg)
New joining strategy: enabling new players to join the system securely
From core-chain to blockchain:adding the transactions back
More…
Next steps
![Page 32: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/32.jpg)
1. non-flat model
2. adaptive difficulty adjustment
3. incentives
4. light clients
5. post quantum security
6. …
More considerations
![Page 33: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/33.jpg)
Earlier draft available at https://eprint.iacr.org/2017/656 latest version available from the authors
![Page 34: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/34.jpg)
This proof-of-stake serves as the “engine” of the Fractal Platformhttps://www.fractalblock.com/
Implementation
FRACTAL
![Page 35: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/35.jpg)
Implementation#node 1000
the length of round 1sdifficulty 0.00004#rounds 1000
network delay 1s~5sgreedy 4
average width 10
![Page 36: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/36.jpg)
Outline • Why mimic Nakamoto’s design
• How to mimic
• Decoupling consensus & data distribution
![Page 37: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/37.jpg)
H( context, payload, solution ) < Tcontext = pointer to the last block in the longest chain
payload = valid TXs from users/networksolution = nonce
Nakamoto’s design
TXs broadcast twice
TX broadcast is the bottleneck >90% bandwidth
Previous: consensus Now: consensus & block distribution
![Page 38: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/38.jpg)
Network physical limit
5000
![Page 39: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/39.jpg)
BackPackers design
![Page 40: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/40.jpg)
A. Bounded-length Routing o Reduce bandwidth consumption o Remove broadcast bottleneck
B. Adaptive rate control+ Lightweight Network Coding o Optimize throughput across nodes o Maximize bandwidth utilization o Always transmit New information
C. Unsolicited flooding of Meta-block: o 10x reduction in block propagation time
Soft transaction sharding o Prevent packers from packing duplicated txs
Provably Near-optimal throughput
Throughput =
Near-optimal Block Propagation Time (propagate along shortest paths)
A
B
C
Θ (Uavg)
BackPackers design
D
![Page 41: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/41.jpg)
Implementation
![Page 42: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/42.jpg)
Thanks
Question?
![Page 43: How to Mimic Nakamoto’s Design - Stanford University · How to Mimic Nakamoto’s Design via Proof-of-Stake Hong-Sheng Zhou Virginia Commonwealth University Fractal Platform Jonathan](https://reader031.fdocuments.us/reader031/viewer/2022021917/5e631a028967b34e7c2d94f8/html5/thumbnails/43.jpg)
• Lei Fan, Jonathan Katz, Hong-Sheng Zhou, A Scalable Proof-of-Stake Blockchain in the Open Setting (or, How to Mimic Nakamoto’s Design via Proof-of-Stake). Early version at https://eprint.iacr.org/2017/656
• Jonathan Katz, Hong-Sheng Zhou, A Proof-of-Stake Protocol with Post-Quantum Security.
• Thang Dinh, Lei Fan, Phuc Thai, Hong-Sheng Zhou, BackPackers: Fast and Secure Block Distribution for High-throughput Blockchain.
Credits