feat: refactor @waku/rln to use rln-wasm for credential generation and remove unused RLN logic

[danisharora099]

Description

The current lightweight credential generator in js-waku was implemented as a workaround that bypasses Zerokit (context). However, this implementation is not secure or robust, and it was agreed that Zerokit should be the canonical way to generate RLN credentials.

Additionally, js-waku does not require RLN proof generation or verification. Since it no longer maintains active support for Relay, most entities in @waku/rln are unnecessary for its current scope.

This issue proposes a focused refactor:

• Use rln-wasm (Zerokit-backed) for credential generation
• Remove all other RLN logic from @waku/rln

User Story

• As a Waku SDK developer, I want to generate RLN credentials securely and minimally, so that js-waku remains lightweight while being compatible with the RLN v2 stack.
• As a downstream application developer, I want to rely on a consistent and secure credential generation mechanism without unnecessary RLN overhead.

Proposed Solution / Feature Design

• Upgrade Zerokit from 0.8.0 to rln-wasm@^0.2.0
• Refactor @waku/rln to remove all unused RLN functionality (proof generation, membership state management, etc.)
• Retain only the credential generation functionality, backed by the updated rln-wasm API

Optional: Diagram or Draft of Design

graph TD
    A[js-waku] -->|uses| B[rln-wasm]
    B -->|wraps| C[generate credentials]

    subgraph Scope_Removed
      D[Proof_Generation]
      E[Verification]
      F[Membership_Management]
    end

    B -.-> D
    B -.-> E
    B -.-> F

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[fryorcraken]

Additionally, js-waku does not require RLN proof generation or verification.

Incorrect, js-waku requires proof generation and verification.

This planned as part of H2 roadmap: https://github.com/waku-org/pm/blob/master/draft-roadmap/integrate_rln_with_waku_api.md#implement-rln-onchain-tree-proof-generation-and-verification-in-the-browser

[weboko]

Remove all other RLN logic from @waku/rln

please, no :)

tho we need to separate logic for credentials and proofs

[danisharora099]

Right. I understand the need for proof generation + verification in js-waku. We cannot upgrade Zerokit in @waku/rln only for credentials generation, without upgrading rest of the code, without maintaining two different versions of Zerokit in the same package. One option is to have a separate package for credentials that uses rln-wasm@0.2.1 and the original @waku/rln continues to use rln-wasm@0.1.0? (#2518)
More details here: https://discord.com/channels/1110799176264056863/1291274218159341619/1399742910232264754

[weboko]

I think we should, in couple of weeks, do following:

• upgrade @waku/rln to use latest zerokit;
• make credentials manager use it and consume it at rln.waku.org;
• implement proof logic using the zerokit;

until then rln.waku.org can stay in the state it is right now (@fryorcraken to confirm)

[fryorcraken]

@fryorcraken to confirm

What do you want me to confirm?
How urgent is it to fix rln.waku.org? Not THAT urgent, because we need to do some smart contract work too: waku-org/pm#331
ie, matter of weeks, not days.