fix: move resources outside rln package

- Put default resources to an external storage and access it through URL
- Add `RLN.create` which downloads the default resources if devs
didn't give resources
- Fix tests

package.json

@@ -68,7 +68,7 @@
     "@semaphore-protocol/group": "^3.10.1",
     "@semaphore-protocol/identity": "^3.10.1",
     "@zk-kit/incremental-merkle-tree": "^0.4.3",
-    "base64-js": "^1.5.1",
+    "axios": "^1.5.0",
     "ethers": "^6.4.0",
     "ffjavascript": "0.2.55",
     "poseidon-lite": "^0.0.2",

src/index.ts

@@ -5,6 +5,6 @@ export { IMessageIDCounter } from './message-id-counter'
 
 export * from './types'
 // Expose helpers
-export { calculateExternalNullifier,  calculateRateCommitment, calculateSignalHash, shamirRecovery } from './common'
+export { calculateExternalNullifier,  calculateRateCommitment, calculateSignalHash, shamirRecovery, DEFAULT_MERKLE_TREE_DEPTH } from './common'
 
 export { RLNFullProof, RLNSNARKProof, RLNWitness, RLNPublicSignals, RLNProver, RLNVerifier, WithdrawProver } from './circuit-wrapper'

src/registry.ts

@@ -177,7 +177,7 @@ export class MemoryRLNRegistry implements IRLNRegistry {
 
   constructor(
     readonly rlnIdentifier: bigint,
-    readonly treeDepth?: number | undefined,
+    readonly treeDepth: number  = DEFAULT_MERKLE_TREE_DEPTH,
   ) {
     this.mapIsWithdrawing = new Map<string, boolean>()
     this.mapMessageLimit = new Map<string, bigint>()

src/resources.ts

@@ -0,0 +1,78 @@
+import { VerificationKey } from './types'
+
+import axios from 'axios'
+
+type ICircuitParams = {
+  wasmFile: string | Uint8Array,
+  finalZkey: string | Uint8Array,
+}
+
+type IRLNParams = ICircuitParams & { verificationKey: VerificationKey }
+type IWithdrawParams = ICircuitParams
+
+// TODO: Change to a more permanent URL after trusted setup is complete
+const resourcesURL = 'https://rln-resources-temp.s3.us-west-1.amazonaws.com/resources'
+const rln20URL = `${resourcesURL}/rln-20`
+const withdrawURL = `${resourcesURL}/withdraw`
+const treeDepthToDefaultRLNParamsURL = {
+  '20': rln20URL,
+}
+
+async function downloadBinary(url: string): Promise<Uint8Array> {
+  const resp = await axios.get(url, { responseType: 'arraybuffer' })
+  return new Uint8Array(resp.data)
+}
+
+function parseVerificationKeyJSON(o: any): VerificationKey {
+  // NOTE: This is not a complete check, to do better we can check values are of the correct type
+  if (!o.protocol) throw new Error('Verification key has no protocol')
+  if (!o.curve) throw new Error('Verification key has no curve')
+  if (!o.nPublic) throw new Error('Verification key has no nPublic')
+  if (!o.vk_alpha_1) throw new Error('Verification key has no vk_alpha_1')
+  if (!o.vk_beta_2) throw new Error('Verification key has no vk_beta_2')
+  if (!o.vk_gamma_2) throw new Error('Verification key has no vk_gamma_2')
+  if (!o.vk_delta_2) throw new Error('Verification key has no vk_delta_2')
+  if (!o.vk_alphabeta_12) throw new Error('Verification key has no vk_alphabeta_12')
+  if (!o.IC) throw new Error('Verification key has no IC')
+  return o
+}
+
+async function downloadVerificationKey(url: string): Promise<VerificationKey> {
+  const resp = await axios.get(url)
+  return parseVerificationKeyJSON(resp.data)
+}
+
+export async function getDefaultRLNParams(treeDepth: number): Promise<IRLNParams | undefined> {
+  const url = treeDepthToDefaultRLNParamsURL[treeDepth.toString()]
+  if (!url) {
+    return undefined
+  }
+  const wasmFileURL = `${url}/circuit.wasm`
+  const finalZkeyURL = `${url}/final.zkey`
+  const verificationKeyURL = `${url}/verification_key.json`
+  const verificationKey = await downloadVerificationKey(verificationKeyURL)
+  const [wasmFile, finalZkey] = await Promise.all([
+    downloadBinary(wasmFileURL),
+    downloadBinary(finalZkeyURL),
+  ])
+  return {
+    wasmFile,
+    finalZkey,
+    verificationKey,
+  }
+}
+
+export async function getDefaultWithdrawParams(): Promise<IWithdrawParams> {
+  const wasmFileURL = `${withdrawURL}/circuit.wasm`
+  const finalZkeyURL = `${withdrawURL}/final.zkey`
+  const [wasmFile, finalZkey] = await Promise.all([
+    downloadBinary(wasmFileURL),
+    downloadBinary(finalZkeyURL),
+  ])
+  return {
+    wasmFile,
+    finalZkey,
+  }
+}
+
+