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Questions tagged [consensus]

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Perpetual preemption attack

From SCP's white paper, it states Our definition of liveness is weak in that it says a node can externalize new values, not that it will. Hence, it admits a state of perpetual preemption in which ...
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0answers
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What is the difference between FAILURE_SAFETY and QUORUM_THRESHOLD?

My assumption is that FAILURE_SAFETY refers to how many nodes in your quorum slice you allow to fail while QUORUM_THRESHOLD refers to the percentage of nodes in an quorum that's necessary to come to a ...
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1answer
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`LEDGER_MAX_TX_SIZE` and `5` seconds `EXP_LEDGER_TIMESPAN_SECONDS` gives only `20` tx per second?

It seems like the consensus nomination period is set to 5 seconds and each ledger size is maximized at 100 transactions per ledger, so that would give 20 transactions per second at best. Am I ...
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29 views

When a lower tier quorum comes to its own consensus

Consider this simple scenario: A <--- B A.QUORUM_SET = [A] A.THRESHOLD = 100 B.QUORUM_SET = [A,B] B.THRESHOLD = 49 So A is a higher tier node that comes to consensus with itself. B is a lower ...
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1answer
34 views

White paper hashing clarification

On page 20 of the Stellar Consensus Protocol white paper the specifics of calculating a weighting for other nodes, the neighbours of a node and the priority of another node are all described. ...
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1answer
44 views

Difference between full & basic validators

I'm not clear on the differences between full validators and basic validators on a network. Taken from official doc, it seems like the differences are mostly an abstraction, with full validators being ...
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1answer
34 views

Could consensus period be changed?

I'm trying to run a private network and so modifying stellar-core's source code is not out of the question. I noticed that the network is right now configured to come to consensus every 5 seconds, ...
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1answer
33 views

Does each node maintain a global ledger?

Consider in the simplest case with two disjoint quorums A and B. If something comes to a consensus in A, does B get the update as well? On a high level view, does each peer on the Stellar network ...
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1answer
44 views

Who creates the ballot?

If I understand this correctly, when a voting is initiated, there's a ballot that holds all the values for which the network is voting on, and it gets propagated to other nodes through the consensus. ...
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1answer
56 views

How can cyclic quorum ever come to a consensus?

Consider the simplest case with three nodes A, B, C, with: Q(A) = {{A,B}} Q(B) = {{B,C}} Q(C) = {{C,A}} So a cyclic graph. How can this ever reach consensus? In order for A to make a decision, he ...
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1answer
82 views

Is Stellar platform a blockchain?

I heard Stellar is a Ripple fork, is that right? Since Ripple does not uses a blockchain, does Stellar use a blockchain?
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1answer
63 views

Nominate --> Prepare --> Commit --> Externalize question

Ok, so I am trying to grok how, if at all, state moves through this setup. Let's say a stellar node receives a transaction from a client that it wants to propose to the network. The node then sends ...
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2answers
93 views

Is there a minimal implementation of Stellar Consensus Protocol besides stellar-core?

I'm learning about consensus and I'd like to explore SCP in depth. However, the stellar-core implementation is difficult for a newcomer to grok. Is there a minimal SCP implementation elsewhere I can ...
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51 views

Is the Stellar Consensus Protocol paper peer reviewed?

Is the stellar consensus protocol peer reviewed? If yes, could you share some resources pointing to the peer review? If not, what would need to happen to have a peer review of this part of the ...
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2answers
134 views

What is asymptotic security and why does Stellar, but not POW exhibit this?

One of the benefits mentioned of SCP in comparison to POW is 'asymptotic security' https://www.stellar.org/blog/stellar-consensus-protocol-proof-code/. What does this form of security mean in practice ...
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27 views

How to initialize the blockchain? [duplicate]

How were the first tokens issued? Modifying the database? is there any special case on the code to accept anything coming from the genesis block?
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1answer
127 views

Questions about SCP and federated voting steps, with a focus on the Internet-Draft

I recently have studied the Stellar Consensus Protocol (SCP) based on the internet draft here: https://datatracker.ietf.org/doc/draft-mazieres-dinrg-scp/. I have several questions as follows. In the ...
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2answers
116 views

Should Every Node Contain The Same Quorum Set Configuration?

Suppose I want to set up four nodes: A, B, C, D. I want A to trust B, and C to trust D, so the set is denoted by {{A, b}, {C, D}}. I want to set up a situation where either one of these sets can vote ...
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1answer
50 views

Stellar failure safety with UNSAFE_QUORUM false

Stellar failure safety is defined as n = 3f+1 <=> f = (n-1)/3 n is number of node and f is failure safety. I have setup 3 nodes with my quorum and THRESHOLD_PERCENT=67 but it is not ...
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1answer
68 views

How does the Stellar Network prevent an actor with small quorum intersection from halting the network

I am thinking through some of the edge cases of adversaries attempting to compromise the Stellar Network. Let's say an adversary creates four consensus bearing Stellar-core nodes and runs all four of ...
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1answer
127 views

How can I query or visualize the quorum slices of the Stellar network?

I think I remember faintly that a while ago there was a JS-based visualization of the quorums between various validators on Stellar but I seem unable to find it again. As far as I understand the ...
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1answer
55 views

How are timestamps deemed invalid?

The Stellar Consensus Protocol orders block candidates (via ballots) by the maximum timestamp and union of their transactions. It says that "values [transactions/ballots] with invalid timestamps will ...
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2answers
474 views

Is Stellar permissionless or permissioned blockchain?

Is Stellar permissionless or permissioned blockchain? or rather (whichever is more adequate) Is SCP permissionless or permissioned consensus protocol?
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1answer
57 views

Is there a simplified or abridged version of the Mazieres paper describing the Stellar Consensus Protocol?

Is there a simplified document describing the Stellar Consensus Protocol that is more accessible and can be understood by the general public? I am trying to clarify and simplify the knowledge around ...
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3answers
184 views

Is Stellar Ledger immutable?

Typical mining guarantees that it is too difficult to recalculate block hashes, therefore, the ledger is practically immutable. How does Stellar ledger achieve immutability? If it does.
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1answer
174 views

When is a slot created in the Stellar Consensus Protocol?

At what time during the protocol is a unique slot created for the nodes to vote on?
3
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1answer
67 views

How are changes in the stellar protocol implemented?

Recently there was a lowering of the base fee from 10 to 0.5 lumens. Typically in a blockchain such a change would require a hard fork. How did all the validators agree to accept the new limit? Did ...
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1answer
64 views

How is node membership handled on Stellar?

I'm looking through the whitepaper and getting a bit confused on an issue. (3.2 Examples and discussion) mentions a tiered structural approach similar to the Internet with various Tier 1 nodes run by ...
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2answers
542 views

How does the Stellar Consensus Protocol prevent Sybil attacks?

A Sybil attack is an attack where a single adversary controls multiple nodes on a network in order to influence voting to their advantage. It is unknown to the rest of the network that the nodes are ...
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1answer
377 views

Are there any known weaknesses in the Stellar Consensus Protocol?

While SCP is superior to POW and POS in many ways, are there any known situations, although infrequent or difficult to meet, where the protocol could not work well or where the network can be attacked ...
35
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1answer
386 views

How are the Stellar (XLM) and Ripple (XRP) protocols different?

How are the Stellar Consensus Protocol and the XRP Ledger Consensus Process different, and what does it mean for users?