![Page 1: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/1.jpg)
Bitcoin: Synchronization andSharing of Transactions
Roger Wattenhofer
ETH Zurich – Distributed Computing Group – www.disco.ethz.ch
![Page 2: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/2.jpg)
![Page 3: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/3.jpg)
20102011
20122013
20142015
0
200
400
600
800
1000
1200
Pri
ce [
USD
/BTC
]
Exchange Rate USD/BTC
![Page 4: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/4.jpg)
![Page 5: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/5.jpg)
What is Bitcoin?
+ + =
![Page 6: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/6.jpg)
Bitcoin Basics
![Page 7: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/7.jpg)
The Bank of Bitcoin
User BalanceA 2B 5C 8
TXB −→ A
User BalanceA 2 4B 5 3C 8
![Page 8: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/8.jpg)
The Bank of Bitcoin
User BalanceA 2B 5C 8
TXB −→ A
User BalanceA 2 4B 5 3C 8
![Page 9: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/9.jpg)
The Bank of Bitcoin
User BalanceA 2B 5C 8
TXB −→ A
User BalanceA 2 4B 5 3C 8
![Page 10: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/10.jpg)
The Bank of Bitcoin
User BalanceA 2B 5C 8
TXB −→ A
User BalanceA 2 4B 5 3C 8
![Page 11: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/11.jpg)
Opening an Account in Bitcoin
Private Key Public Key Address
![Page 12: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/12.jpg)
Transferring Bitcoins
TX: 41b221
B0.1
A4.798
A4.899
Inputs OutputsFee
0.001
Prev. TX:a1a53743
4.899
0
C...
1
|Outputs
![Page 13: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/13.jpg)
Transferring Bitcoins
TX: 41b221
B0.1
A4.798
A4.899
Inputs OutputsFee
0.001
Prev. TX:a1a53743
4.899
0
C...
1
|Outputs
![Page 14: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/14.jpg)
Transferring Bitcoins
TX: 41b221
B0.1
A4.798
A4.899
Inputs OutputsFee
0.001
Prev. TX:a1a53743
4.899
0
C...
1
|Outputs
![Page 15: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/15.jpg)
Transferring Bitcoins
TX: 41b221
B0.1
A4.798
A4.899
Inputs OutputsFee
0.001
Prev. TX:a1a53743
4.899
0
C...
1
|Outputs
![Page 16: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/16.jpg)
Transferring Bitcoins
TX: 41b221
B0.1
A4.798
A4.899
Inputs Outputs
Fee
0.001
Prev. TX:a1a53743
4.899
0
C...
1
|Outputs
![Page 17: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/17.jpg)
Transferring Bitcoins
TX: 41b221
B0.1
A4.798
A4.899
Inputs OutputsFee
0.001
Prev. TX:a1a53743
4.899
0
C...
1
|Outputs
![Page 18: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/18.jpg)
Transferring Bitcoins
TX: 41b221
B0.1
A4.798
A4.899
Inputs OutputsFee
0.001
Prev. TX:a1a53743
4.899
0
C...
1
|Outputs
![Page 19: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/19.jpg)
Distributing the Bank
User BalanceA 2B 5C 8
TX
TX
![Page 20: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/20.jpg)
Distributing the Bank
TX
![Page 21: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/21.jpg)
Distributing the Bank
TX
![Page 22: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/22.jpg)
Distributing the Bank
TX
![Page 23: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/23.jpg)
Distributing the Bank
TX
![Page 24: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/24.jpg)
Distributing the Bank
TX
![Page 25: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/25.jpg)
Let’s Buy a Snack
[Bamert, Decker, Elsen, W, Welten, 2013]
![Page 26: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/26.jpg)
Doublespending
TX B1
A
1
1
Inputs
Outputs
TX’ A1
1
�
![Page 27: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/27.jpg)
Doublespending
TX B1
A
1
1
Inputs
Outputs
TX’ A1
1
�
![Page 28: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/28.jpg)
Doublespending
TX B1
A
1
1
Inputs
Outputs
TX’ A1
1
�
![Page 29: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/29.jpg)
Transaction Conflicts
TX
TX
![Page 30: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/30.jpg)
Transaction Conflicts
TX
TX
![Page 31: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/31.jpg)
Transaction Conflicts
TX
TX
![Page 32: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/32.jpg)
Transaction Conflicts
TX
TX
![Page 33: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/33.jpg)
Resolving Conflicts
Green!
![Page 34: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/34.jpg)
Resolving Conflicts
Green!
![Page 35: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/35.jpg)
Resolving Conflicts
Green!
![Page 36: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/36.jpg)
How to Choose a Leader?
![Page 37: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/37.jpg)
Proof-of-Work
Block
H(Previous Block)
TX TX TX TX
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 38: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/38.jpg)
Proof-of-Work
Block
H(Previous Block)
TX TX TX TX
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 39: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/39.jpg)
Proof-of-Work
Block
H(Previous Block) TX TX TX TX
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 40: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/40.jpg)
Proof-of-Work
Block
H(Previous Block) TX TX TX TX
I H(Block) → fd2e2055f117bfa261b5a6c7e11df367. . .
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 41: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/41.jpg)
Proof-of-Work
Block
H(Previous Block) TX TX TX TX Nonce
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 42: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/42.jpg)
Proof-of-Work
Block
H(Previous Block) TX TX TX TX Nonce
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 43: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/43.jpg)
Proof-of-Work
Block
H(Previous Block) TX TX TX TX Nonce
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 44: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/44.jpg)
Proof-of-Work
Block
H(Previous Block) TX TX TX TX Nonce
I H(Block|0) → 094d66aa7c844a9dbb516a41259b5877. . .
I H(Block|1) → f2496854af8bf989171587a9259f634f. . .
I H(Block|2) → aec87c0ca2e5eb3f23111092f1089ada. . .
I H(Block|3) → 777f75b2a8ecfdc8026c236fc1d2ffa0. . ....
I H(Block|961127) → 0000014823419622d4c133672a7d657e. . .
![Page 45: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/45.jpg)
The Blockchain
Time
![Page 46: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/46.jpg)
The Blockchain
Time
![Page 47: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/47.jpg)
Is Bitcoin stable?
![Page 48: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/48.jpg)
The Blockchain
Time
![Page 49: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/49.jpg)
The Blockchain
Time
![Page 50: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/50.jpg)
Propagation Speed
0 10 20 30 40 50 60Time since first observation [s]
0.00
0.02
0.04
0.06
0.08
0.10
0.12PD
FBlock propagation
[Decker, W, 2013]http://bitcoinstats.com
![Page 51: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/51.jpg)
Propagation Speed
0 10 20 30 40 50 60Time since first observation [s]
0.00
0.02
0.04
0.06
0.08
0.10
0.12PD
FBlock propagation
50thp
erc.[Decker, W, 2013]http://bitcoinstats.com
![Page 52: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/52.jpg)
Propagation Speed
0 10 20 30 40 50 60Time since first observation [s]
0.00
0.02
0.04
0.06
0.08
0.10
0.12PD
FBlock propagation
50thp
erc.
95thp
erc.
[Decker, W, 2013]http://bitcoinstats.com
![Page 53: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/53.jpg)
Propagation Speed
0 10 20 30 40 50 60Time since first observation [s]
0.00
0.02
0.04
0.06
0.08
0.10
0.12PD
FBlock propagation
[Decker, W, 2013]http://bitcoinstats.com
![Page 54: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/54.jpg)
Blockchain Forks
180000 182000 184000 186000 188000 190000Blockchain Height
0
2
4
6
8
10
12
Fork
sBlockchain forks
1.69%
[Decker, W, 2013]
![Page 55: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/55.jpg)
Aside: Mining Evolution
20102011
20122013
20142015
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
Hash
rate
PH
/s
Hashrate evolution
![Page 56: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/56.jpg)
Aside: Mining Evolution
20102011
20122013
20142015
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
Hash
rate
PH
/s
Hashrate evolution
![Page 57: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/57.jpg)
Aside: Mining Evolution
20102011
20122013
20142015
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
Hash
rate
PH
/s
Hashrate evolution
![Page 58: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/58.jpg)
Summary
TX
Green!
Block
H(Previous Block) TX TX TX TX Nonce
Time
![Page 59: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/59.jpg)
How to Lose $500M
![Page 60: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/60.jpg)
Addressing Transaction Malleability: MtGox has detectedunusual activity on its Bitcoin wallets and performedinvestigations during the past weeks.
![Page 61: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/61.jpg)
The MtGox Incident
I July 2010: First trade on MtGox
I May 2011: Transaction malleability identified as low priority issue
I February 7, 2014: MtGox halts withdrawals
I February 10, 2014: MtGox announces loss of 850,000 bitcoins (620millio USD) and cites transaction malleability as root cause
I February 28, 2014: MtGox files for bankruptcy
I March 7 2014: MtGox finds 200,000 bitcoins
I August 2015: MtGox CEO is arrested
![Page 62: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/62.jpg)
Signatures
00 00
61 af bb 4d e9 f8 b8 74 86 1e
There are multiple ways to serialize a signature:
I Multiple push operations (1 byte, 2 byte, 4 byte)
I Non-canonical DER encodings
I Padding
I . . .
![Page 63: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/63.jpg)
Signatures
00 00 61 af bb 4d e9 f8 b8 74 86 1e
There are multiple ways to serialize a signature:
I Multiple push operations (1 byte, 2 byte, 4 byte)
I Non-canonical DER encodings
I Padding
I . . .
![Page 64: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/64.jpg)
Transaction Malleability Attack
TX
TX
TX
TX
TX
Red!
TX?Refund
![Page 65: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/65.jpg)
Transaction Malleability Attack
TX
TX
TX
TX
TX
Red!
TX?Refund
![Page 66: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/66.jpg)
Transaction Malleability Attack
TX
TX
TX
TX
TX
Red!
TX?Refund
![Page 67: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/67.jpg)
Transaction Malleability Attack
TX
TX
TX
TX
TX
Red!
TX?Refund
![Page 68: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/68.jpg)
Transaction Malleability Attack
TX
TX
TX
TX
TX
Red!
TX?
Refund
![Page 69: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/69.jpg)
Transaction Malleability Attack
TX
TX
TX
TX
TX
Red!
TX?
Refund
![Page 70: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/70.jpg)
Incident Timeline
Feb 01 2014
Feb 04 2014
Feb 07 2014
Feb 10 2014
Feb 13 2014
Feb 16 2014
Feb 19 2014
Feb 22 2014
Feb 25 2014
Feb 28 20140
50000
100000
150000
200000
250000
300000
350000
bit
coin
s
0
5000
10000
15000
20000
25000
30000
transa
ctio
ns
1st
Pre
ss R
ele
ase
2nd P
ress
Rele
ase
Cumulative malleable doublespends
value
number
386 BTC
[Decker, W, 2014]
![Page 71: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/71.jpg)
Incident Timeline
Feb 01 2014
Feb 04 2014
Feb 07 2014
Feb 10 2014
Feb 13 2014
Feb 16 2014
Feb 19 2014
Feb 22 2014
Feb 25 2014
Feb 28 20140
50000
100000
150000
200000
250000
300000
350000
bit
coin
s
0
5000
10000
15000
20000
25000
30000
transa
ctio
ns
1st
Pre
ss R
ele
ase
2nd P
ress
Rele
ase
Cumulative malleable doublespends
value
number
386 BTC
[Decker, W, 2014]
![Page 72: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/72.jpg)
Is Bitcoin Secure?
![Page 73: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/73.jpg)
Securing Your Bitcoins
[Bamert, Decker, W, 2013]
![Page 74: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/74.jpg)
Does Bitcoin Scale?
![Page 75: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/75.jpg)
The Bitcoin Ecosystem is Growing
20102011
20122013
20142015
0
20000
40000
60000
80000
100000
120000
140000
Tra
nsa
ctio
ns
Daily Transaction Volume
![Page 76: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/76.jpg)
Scalability Limits
I Disk space: < 500 transactions per second
I Processing power: < 200 transactions per second
I Network bandwidth: < 100 transactions per second
I Artificial 1MB limit: < 3 transactions per second
Today:
I Bitcoin: 1 transaction per second
I Credit Cards: > 10, 000 transactions per second
![Page 77: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/77.jpg)
Scalability Limits
I Disk space: < 500 transactions per second
I Processing power: < 200 transactions per second
I Network bandwidth: < 100 transactions per second
I Artificial 1MB limit: < 3 transactions per second
Today:
I Bitcoin: 1 transaction per second
I Credit Cards: > 10, 000 transactions per second
![Page 78: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/78.jpg)
Scalability Limits
I Disk space: < 500 transactions per second
I Processing power: < 200 transactions per second
I Network bandwidth: < 100 transactions per second
I Artificial 1MB limit: < 3 transactions per second
Today:
I Bitcoin: 1 transaction per second
I Credit Cards: > 10, 000 transactions per second
![Page 79: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/79.jpg)
Scalability Limits
I Disk space: < 500 transactions per second
I Processing power: < 200 transactions per second
I Network bandwidth: < 100 transactions per second
I Artificial 1MB limit: < 3 transactions per second
Today:
I Bitcoin: 1 transaction per second
I Credit Cards: > 10, 000 transactions per second
![Page 80: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/80.jpg)
Scalability Limits
I Disk space: < 500 transactions per second
I Processing power: < 200 transactions per second
I Network bandwidth: < 100 transactions per second
I Artificial 1MB limit: < 3 transactions per second
Today:
I Bitcoin: 1 transaction per second
I Credit Cards: > 10, 000 transactions per second
![Page 81: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/81.jpg)
Payment Network
![Page 82: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/82.jpg)
Payment Network
![Page 83: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/83.jpg)
Payment Network
![Page 84: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/84.jpg)
Micropayment Channels
5
5
T=100 5
5
0
4
1
3
2
![Page 85: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/85.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 86: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/86.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 87: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/87.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 88: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/88.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 89: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/89.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 90: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/90.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 91: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/91.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 92: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/92.jpg)
Micropayment Channels
5 5
T=100 5
5
0
4
1
3
2
![Page 93: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/93.jpg)
Atomic Multiparty Opt-In
![Page 94: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/94.jpg)
Atomic Multiparty Opt-In
![Page 95: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/95.jpg)
Atomic Multiparty Opt-In
![Page 96: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/96.jpg)
Invalidating Transactions
T=100
T=99
![Page 97: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/97.jpg)
Invalidating Transactions
T=100
T=99
![Page 98: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/98.jpg)
Bidirectional Transfers
5 5
5
0
4 4
4
0
0
5
1
3
![Page 99: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/99.jpg)
Bidirectional Transfers
5 5
5
0
4 4
4
0
0
5
1
3
![Page 100: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/100.jpg)
Bidirectional Transfers
5 5
5
0
4 4
4
0
0
5
1
3
![Page 101: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/101.jpg)
Duplex Micropayment Channels
Setup Invalidation Tree Micropayment Channels
T = 100 T = 100 T = 100
T = 99 T = 100 T = 100
T = 99 T = 100
T = 99
![Page 102: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/102.jpg)
Duplex Micropayment Channels
Setup Invalidation Tree Micropayment Channels
T = 100 T = 100 T = 100
T = 99 T = 100 T = 100
T = 99 T = 100
T = 99
![Page 103: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/103.jpg)
Duplex Micropayment Channels
Setup Invalidation Tree Micropayment Channels
T = 100 T = 100 T = 100
T = 99 T = 100 T = 100
T = 99 T = 100
T = 99
![Page 104: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/104.jpg)
Duplex Micropayment Channels
Setup Invalidation Tree Micropayment Channels
T = 100 T = 100 T = 100
T = 99 T = 100 T = 100
T = 99 T = 100
T = 99
![Page 105: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/105.jpg)
Duplex Micropayment Channels
Setup Invalidation Tree Micropayment Channels
T = 100 T = 100 T = 100
T = 99 T = 100 T = 100
T = 99 T = 100
T = 99
![Page 106: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/106.jpg)
Summary
Red!
TX?Refund
T = 100 T = 100 T = 100
T = 99 T = 100 T = 100
T = 99 T = 100
T = 99
![Page 107: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/107.jpg)
Thank you, questions?
Thanks to Christian Decker
ETH Zurich – Distributed Computing Group – www.disco.ethz.ch
![Page 108: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/108.jpg)
Securing Fast Payments
![Page 109: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/109.jpg)
Let’s Buy a Snack
[Bamert, Decker, Elsen, W, Welten, 2013]
![Page 110: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/110.jpg)
Transaction Confidence
TX
confidence(TX ) =
![Page 111: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/111.jpg)
Transaction Confidence
TX
confidence(TX ) =
![Page 112: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/112.jpg)
Transaction Confidence
TX
confidence(TX ) =
![Page 113: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/113.jpg)
Transaction Confidence
TX
confidence(TX ) =
![Page 114: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/114.jpg)
Transaction Confidence
TX
confidence(TX ) =
![Page 115: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/115.jpg)
Doublespend Detection
0 20 40 60 80 100Node sample size
0.0
0.2
0.4
0.6
0.8
1.0D
ete
ctio
n p
robabili
tyDoublespend detection
[Bamert, Decker, Elsen, W, Welten, 2013]
![Page 116: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/116.jpg)
Time to Detection
20 40 60 80 100Node sample size
0
2
4
6
8
10
12
14
Tim
e [
s]Time until detection
Average time
Median time
95 percentile
99 percentile
[Bamert, Decker, Elsen, W, Welten, 2013]
![Page 117: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/117.jpg)
Successful Doublespend
0 20 40 60 80 100Node sample size
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
Pro
babili
tyProbability of successful double spend
[Bamert, Decker, Elsen, W, Welten, 2013]
![Page 118: Bitcoin: Synchronization and Sharing of Transactions · The MtGox Incident I July 2010: First trade on MtGox I May 2011: Transaction malleability identi ed as low priority issue I](https://reader033.vdocument.in/reader033/viewer/2022050513/5f9d61bd8f18217799242b33/html5/thumbnails/118.jpg)
Successful Doublespend
0 20 40 60 80 100Node sample size
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
Pro
babili
tyProbability of successful double spend
0.088%
[Bamert, Decker, Elsen, W, Welten, 2013]