the graph of transactions in the iota cryptocurrency graph of...ref to block 1 block of data 3 ref...

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The graph of transactions in the IOTA cryptocurrency

Jun, 20th, 2018, Clermont-Ferrand

Quentin Bramas [email protected]

1

Talk ChainIntroduction

2

The Tangle

Unconfirmed Transactions

Parasite Chain Attack

Conclusion

The TangleIntroduction

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Data is distributed :


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Data is distributed :no single point of failure


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Data is distributed :no single point of failureno central Authority


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Data is distributed :no single point of failureno central Authorityno need to trust the others


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Data is distributed :no single point of failureno central Authorityno need to trust the others

I want to add some data


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Blockchain:

Block of data 1 Block of data 2

ref to block 1

Block of data 3

ref to block 2


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Basic principle of the Bitcoin Protocol :

Blockchain:


ref to block 1

Block of data 3

ref to block 2


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Basic principle of the Bitcoin Protocol : - Choose randomly one node

Blockchain:


ref to block 1

Block of data 3

ref to block 2


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Basic principle of the Bitcoin Protocol : - Choose randomly one node

The more computing power, the more chance you have to be selected

Blockchain:


ref to block 1

Block of data 3

ref to block 2


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Basic principle of the Bitcoin Protocol : - Choose randomly one node- This node decides what to write in the Blockchain

The more computing power, the more chance you have to be selected

Blockchain:


ref to block 1

Block of data 3

ref to block 2


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ProblemIt does not scale

The Tangle Unconfirmed TransactionsIntroduction

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The Tangle (IOTA)


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The Tangle (IOTA)

Each transaction is a small block that reference two previous ones


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The Tangle (IOTA)


You come up with a DAG (Directed Acyclic Graph)


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The Tangle (IOTA)


You come up with a DAG (Directed Acyclic Graph)

You’re only limited by bandwidth and storage


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The Tangle (IOTA)


sites


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The Tangle (IOTA)


sites

tips (unconfirmed sites)


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The Tangle (IOTA)


sites

tips (unconfirmed sites)

A new site and its parents should not create conflicts.


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The Tangle (IOTA)

How to read a value?


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The Tangle (IOTA)


If you take a tip, you can order transactions and do the same as in a blockchain


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The Tangle (IOTA)

What if tips are conflicting?

A new site cannot confirm conflicting sites



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The Tangle (IOTA)

What if tips are conflicting?


Two conflicting tangles can appear

Which one is correct?


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The Tangle (IOTA)

Tip Selection Algorithm (TSA):- so we know how to read values- so we know where to extend the Tangle


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The Tangle (IOTA)

Tip Selection Algorithm (TSA):- so we know how to read values- so we know where to extend the Tangle

In Bitcoin, we read values from, and we try to extend, the longest chain. If you don’t follow this, you’ll lose money.


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The Tangle (IOTA)

In the Tangle, forks are ok if not conflicting


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The Tangle (IOTA)


But conflicting forks are worst in this case


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The Tangle (IOTA)


So its better to have something like this


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The Tangle (IOTA)


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The Tangle (IOTA)

Should be chosen with higher probability


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The Tangle (IOTA)Compute cumulative weight to each site


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1

1

1

2

6

3

35

8

6

1

11

12

8

15


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1

1

1

2

6

3

35

8

6

1

11

12

8

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Perform a random walk


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11

12

15



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11

12

15


4

3


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11

12

15


Transition function:

4

3


17


11

12

15



4

3

MCMC


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11

12

15



4

3

LMCMCMCMC

The Tangle Unconfirmed Transactions Parasite Chain Attack

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How many tips are left behind ?


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How many tips over the time ?



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- theoretical analysis, assuming random tip selection


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- theoretical analysis, assuming random tip selection- by simulation, for other tip selection


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Theoretical analysis, assuming random tip selection

Discrete time model. At each round: Poisson(𝝀) new sites


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The Tangle Unconfirmed Transactions Necessary Security Assumption

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By simulation, for other tip selection


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By simulation, for other tip selection

number of tips

Unconfirmed Transactions Parasite Chain Attack Conclusion

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Double Spending Attack


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Double Spending Attack Alice send 10 IOTA to Bob for a sandwich


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Double Spending Attack Alice send 10 IOTA to Bob for a sandwichBob waits to see the transaction in the Tangle


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Double Spending Attack Alice send 10 IOTA to Bob for a sandwichBob waits to see the transaction in the TangleBob gives Alice the sandwich


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Double Spending Attack Alice send 10 IOTA to Bob for a sandwichBob waits to see the transaction in the TangleBob gives Alice the sandwichAlice generates a lots of transactions so that her first transaction is discarded


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Double Spending Attack Alice send 10 IOTA to Bob for a sandwichBob waits to see the transaction in the TangleBob gives Alice the sandwichAlice generates a lots of transactions so that her first transaction is discardedAlice eats the sandwich


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The parasite chain attack


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Theoretical analysis


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Theoretical analysisSimulations


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An attack is possible if hashing power of the adversary hashing power used by the all nodes.

An attack is possible if hashing power of the adversary hashing power of the all nodes

if all the honest nodes constantly generates new sites

Theorem

Corollary



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How many red site so that:

By simulation


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Parasite Chain Attack Conclusion

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Conclusion


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Conclusion

The Tangle (Theoretical Protocol) : Security based on PoW IOTA (Current Implementation) : Central coordinator


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Conclusion

How to attach the parasite chain?



47

Conclusion

Number of tips Resistance to parasite chain attack

How to attach the parasite chain?


the graph of transactions in the iota cryptocurrency graph of...ref to block 1 block of data 3 ref...

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