PERUN: Virtual Payment Hubs over Cryptocurrencies...PERUN in a Nutshell New cryptographic protocol...
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PERUN: Virtual Payment Hubs over Cryptocurrencies Stefan Dziembowski Lisa Eckey Sebastian Faust Daniel Malinowski
Transcript of PERUN: Virtual Payment Hubs over Cryptocurrencies...PERUN in a Nutshell New cryptographic protocol...
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PERUN: Virtual Payment Hubs over
Cryptocurrencies StefanDziembowski
LisaEckey
SebastianFaust
DanielMalinowski
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Goal: Microtransactions
Blockchain Scalability
Problem:Blockchaintransactionsareslowandexpensive
TransactionFees
Alice Bob
SendtoBob
Cheap Fast Offline Secure 2
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Smart Contracts
SmartContract
Storeandsendcoins
Executecode
StoredataLock Interact
Gas
Alice Bob
3 Guaranteedbytheunderlyingcryptocurrency
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PERUN in a Nutshell
Newcryptographicprotocolthatallowsmicrotransactionsovercryptocurrencies
• Basedonsmartcontracts• InaHub-network
2Typesofpaymentchannels• Ledgerchannels:buildovertheblockchain• Virtualchannels:buildoverledgerchannels
Ledger Payment Channels
Virtual Payment Channels
Cheap Fast Offline Secure
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Outline
o Motivation
o LedgerPaymentChannels
o VirtualPaymentChannels
o Security&Performance
o Summary&Outlook5
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1. Create 2. Update 3. Close
(Ledger) Payment Channels*
Alice Bob
LockcA LockcBChannel Contract (cA + cB coins)
* Lightning,Spilman,Duplex,Sprites,Raiden,Counterfactual,L2….
6 1. Create 2. Update 3. Close
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Off-chainchannelstate:sv=(xA,xB,v)
Alice Bob
cA cB
s1=(cA+5,cB-5,1)
s0=(cA,cB,0) s1=(cA+5,cB-5,1)
s0=(cA,cB,0)Cheap Fast Offline Secure
updates1
updates1
+5 -5
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chanAB
(Ledger) Payment Channels
1. Create 2. Update 3. Close
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(Ledger) Payment Channels
Alice Bob
…
Channel Contract
snisvalidifq xA+xB=cA+cBq AprovedbyAandB...Waitformessage
fromBob...
sn=(xA,xB,n) sm=(xA,xB,m)
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Sendsn Sendsm
UnlockxA UnlockxBSelectmorerecentstate
forpayout
1. Create 2. Update 3. Close
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Outline
o Motivation
o LedgerPaymentChannels
o VirtualPaymentChannels
o Security&Performance
o Summary&Outlook9
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Hashed Time Locked Contracts (HTLC)*
Idea:Routeeverytransactionviaintermediary
chanIB
* J.Poon,T.Dryja:Thebitcoinlightningnetwork:Scalableoff-chaininstantpayments.(2016)
Alice Bob
Ingrid
Fee
chanAI
ZZ
IngridpaysAliceifBobpaysIngrid
Ingridpays
Bobif
AlicepaysIn
grid
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PERUN Virtual Channels
chanIB
Alice
Ingrid
chanAIBob
Cheap Fast Offline Secure
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chanAB
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PERUN Virtual Channels
Alice Bob
cI-1
cA-1cB-1
cI-1
openvirtualchanAB
openvirtualchanAB
openvirtualchanAB
Ingrid
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chanIBchanAI2
2chanIBchanAI
1. Create 2. Update 3. Close
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PERUN Virtual Channels
Alice
Ingrid
cI-1
cA-1 cB-1
cI-1
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chanIBchanAI
1 1
vs0=(1,1,0)
Bob
1. Create 2. Update 3. Close
sm=(cA-1,cI-1,m)
vs0=(1,1,0)
sn=(cI-1,cB-1,n)
2 0
updatevs1
vs1=(2,0,1) vs1=(2,0,1) 13
chanAB
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PERUN Virtual Channels
Alice
Ingrid
Bob
cI-1
cA-1cB-1
cI-1
laststate:vsn laststate:vsm
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chanIBchanAI
1. Create 2. Update 3. Close
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PERUN Virtual Channels
Alice
Ingrid
Bob
cI-1
cA+1cB-1
cI+1
updatechanAI
updatechanIB
updatechanIB
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chanIBchanAI
Ingrid stays financially neutral
cA+1cI+1
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updatechanAI
1. Create 2. Update 3. Close
cA-1cI-1
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Outline
o Motivation
o LedgerPaymentChannels
o VirtualPaymentChannels
o Security&Performance
o Summary&Outlook16
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(Informal) PERUN Security
• Balanceneutralityforintermediary
• Consensusonchannelcreationandupdate
• GuaranteedbalancepayoutforAlice&Bob
• Guaranteedchannelclosing
ThismustholdevenifALLotherplayerscollude
Validity=t
2 2
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PERUN Performance Virtual
Channel HTLC
Network Ledger
Channel
ChannelOpening
Update
Agreement
DisagreementClosing
on-chain off-chain/viaIngridoff-chain/direct
off-chain/viaIngrid
off-chain/direct
on-chain off-chain/viaIngrid
on-chain on-chain on-chain
12ct.
55ct.
50ct.
84ct.84ct.
Fee/Payment
Fee/Validity
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Outline
o Motivation
o LedgerPaymentChannels
o VirtualPaymentChannels
o Security&Performance
o Summary&Outlook19
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Summary
• Newformalismforpaymentchannels
• Virtualpaymentchannels• Canbeopenedandclosedoff-chain• Canbeupdatedwithoutintermediary
• Provablesecureprotocol• NewmodelofDLandSmartContracts• RigoroussecurityproofinUCmodel
Extensions
GeneralStateChannelNetworks
Multi-partyVirtualStateChannels
@CCS2018
@Eurocrypt20
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Formoreinformationvisit:
www.perun.network
Thank you for your attention!
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