feat: implement incremental merkle tree

[YashBit]

Important:

1. Creating a simple PR for just a feedback loop, code not ready yet. Will update the description, etc when I have made all the commits.
2. Want to check if I am on the correct path and implementing all the necessary components.

Description

[YashBit]

@cedoor I have created a DynamicCalculator trait which will works the same way but with the depth as a parameter now. This basically controls the loop.

In -> packages/merkle-trees/src/incremental_merkle/tree.nr

Questions:

1. Please let me know if this is the correct direction of implementation with a simple new modified trait that I have completed.

2. After which I will focus on the MembershipProver, etc methods. Then write the Poseidon Hash tests.

For the tests, how would you like me to test the dynamic depth function? So I should create a tree (let's say of depth 4), and then calculate the results for depth 1, 2, 3?

[cedoor]

@YashBit there's code which is not related to this PR (e.g. ecdh). I think you need to open a PR for the binary merkle tree by forking the main branch of zk-kit.noir.

[cedoor]

@YashBit

1. Please let me know if this is the correct direction of implementation with a simple new modified trait that I have completed.

The trait seems to be fine, I added other comments for some files that are actually just a copy of the current Merkle tree. You should be able to re-use that code.

2. After which I will focus on the MembershipProver, etc methods. Then write the Poseidon Hash tests.

Yes, those functions still need to be implemented I guess.

For the tests, how would you like me to test the dynamic depth function? So I should create a tree (let's say of depth 4), and then calculate the results for depth 1, 2, 3?

Exactly, sounds like a good way to test them. Please, take a look at these tests here: https://github.com/privacy-scaling-explorations/zk-kit.circom/blob/326cef9fdb9a2f845b890cffea0594975768be1f/packages/binary-merkle-root/tests/binary-merkle-root.test.ts#L98. You should have the same tests in Noir here.

Also, be aware that this is not an incremental Merkle tree. It works as a general binary Merkle tree with an addition feature: dynamic depth, i.e. the ability to generate a proof with an arbitrary depth even if there's a maximum depth in the circuit (which must be static by design).

[signorecello]

Converting to draft while not ready to merge

[YashBit]

@signorecello Please can you change this back from the draft? The core logic is complete, adding a few tests now.

[YashBit]

@signorecello

Could you please comment on the algorithm? Most of it should remain the same, it is just the calculate_root_dynamic
function in now a new trait called DynamicCalculator which should be able to handle the depth function dynamically.

Thank you again.

[sripwoud]

@YashBit CI is (style check ) is failing. Can you please address this issue? I think you should be familiar with that situation given what you've learnt by working on #8

[sripwoud]

@YashBit I think you need to rebase your branch on main. This PR shows up changes related to eg mocha dependencies while you added these in #8 already.

And formatting CI check is still failing

[YashBit]

@sripwoud I will make those changes.

I am mainly concerned with the logic of the incremental tree. That is the most important, since after that I will be done with unit the tests as well.

[signorecello]

Hey @YashBit I don't understand the goal here. When you use this library in a circuit, you won't be able to pass anything other than an array into its main circuit.

I don't believe we should merge this PR without a bin circuit that would show its usage

[cedoor]

@YashBit can we close this PR in favor of #16 ?

[YashBit]

@cedoor Yes, please close this one!