Skip to content
This repository was archived by the owner on Mar 23, 2026. It is now read-only.

Update requirements.md#58

Open
drequinox wants to merge 4 commits into
masterfrom
drequinox-patch-1
Open

Update requirements.md#58
drequinox wants to merge 4 commits into
masterfrom
drequinox-patch-1

Conversation

@drequinox

Copy link
Copy Markdown

Proposing the safety and liveness properties of the consensus algorithm

Comment thread docs/requirements.md Outdated
* SHOULD have a specification sufficient to enable implemetation without having to refer to someone else's code;
* The consensus algorithm MUST support the following safety and liveness properties
- Agreement — Two different processes MUST decide the same block (agree on the same block).
- Validity — An honest validator MUST have proposed the decided block, and the proposal itself must be a valid block.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

There exists no consensus protocol that can discriminate whether a block has been proposed by an honest validator or it has been proposed by a Byzantine validator that is acting correctly.
We can only discriminate whether it is a valid block.

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I suggest changing validity to

  • Validity — The decided block MUST be a valid block.

And adding the following property, which I do not mind how it is called

  • From any point in time, a block proposed by an honest validator will be eventually added to the chain

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I do not understand the "Validity" requirement above :-(

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

validity means that the proposed block must have been proposed by a node on the network and must be a valid block. in other words, the finally decided block must have come from a valid node (no out of band message should be accepted). Validity conditions are the same as standard Ethereum, however, consensus algorithm can add its own additional elements in the data structure which can be listed separately. Simply it really means checks under isValidBlock().

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I suggest changing validity to

  • Validity — The decided block MUST be a valid block.

And adding the following property, which I do not mind how it is called

  • From any point in time, a block proposed by an honest validator will be eventually added to the chain

I agree with the first one partially, but second part of defintion is more of a liveness / progress realted property. Validity doesnt have to do anything with eventuality of the system. perhaps we can say "Proposed block must have been proposed by a node on the network and must be a valid block"

@drequinox

Copy link
Copy Markdown
Author

I have updated the requirements, please review.

Comment thread docs/requirements.md Outdated
* MUST guarantee all of the requirements listed here when operating in eventually synchronous network
* SHOULD have a specification sufficient to enable implemetation without having to refer to someone else's code;
* The consensus algorithm MUST support the following safety and liveness properties
- Agreement — Two different processes MUST decide the same block (no two processes decide different blocks).

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I suggest changing it with:
Any two honest processes MUST decide the same block (no two honest processes decide different blocks)

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

agreed

Comment thread docs/requirements.md Outdated
* SHOULD have a specification sufficient to enable implemetation without having to refer to someone else's code;
* The consensus algorithm MUST support the following safety and liveness properties
- Agreement — Two different processes MUST decide the same block (no two processes decide different blocks).
- Validity — If a process decides on a block, then that block must have been proposed by some process. Secondly the proposal itself must be a valid block.

@saltiniroberto saltiniroberto Nov 19, 2019

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

If an honest process ...

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

agreed

Comment thread docs/requirements.md Outdated
* The consensus algorithm MUST support the following safety and liveness properties
- Agreement — Two different processes MUST decide the same block (no two processes decide different blocks).
- Validity — If a process decides on a block, then that block must have been proposed by some process. Secondly the proposal itself must be a valid block.
- Integrity — A process MUST only decide for a block at most once (in a round)

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

An honest process ...

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

agreed

Comment thread docs/requirements.md Outdated
- Agreement — Two different processes MUST decide the same block (no two processes decide different blocks).
- Validity — If a process decides on a block, then that block must have been proposed by some process. Secondly the proposal itself must be a valid block.
- Integrity — A process MUST only decide for a block at most once (in a round)
- Termination — Each honest process MUST eventualy decide (ensuring progress)

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Any honest process ...

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

agreed

Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

3 participants