Merge pull request #588 from semaphore-protocol/refactor/merkle-proof

Support `MerkleProof` parameter in the `generateProof` function

Former-commit-id: 2b52ea3

Author: cedoor

packages/proof/src/generate-proof.ts

@@ -1,6 +1,6 @@
 import { BigNumber } from "@ethersproject/bignumber"
 import { BytesLike, Hexable } from "@ethersproject/bytes"
-import { Group } from "@semaphore-protocol/group"
+import type { Group, MerkleProof } from "@semaphore-protocol/group"
 import type { Identity } from "@semaphore-protocol/identity"
 import { NumericString, groth16 } from "snarkjs"
 import getSnarkArtifacts from "./get-snark-artifacts.node"
@@ -11,7 +11,7 @@ import { SemaphoreProof, SnarkArtifacts } from "./types"
 /**
  * Generates a Semaphore proof.
  * @param identity The Semaphore identity.
- * @param group The Semaphore group or its Merkle proof.
+ * @param groupOrMerkleProof The Semaphore group or its Merkle proof.
  * @param scope The external nullifier.
  * @param message The Semaphore signal.
  * @param merkleTreeDepth The depth of the tree with which the circuit was compiled.
@@ -20,14 +20,21 @@ import { SemaphoreProof, SnarkArtifacts } from "./types"
  */
 export default async function generateProof(
     identity: Identity,
-    group: Group,
+    groupOrMerkleProof: Group | MerkleProof,
     message: BytesLike | Hexable | number | bigint,
     scope: BytesLike | Hexable | number | bigint,
     merkleTreeDepth?: number,
     snarkArtifacts?: SnarkArtifacts
 ): Promise<SemaphoreProof> {
-    const leafIndex = group.indexOf(identity.commitment)
-    const merkleProof = group.generateMerkleProof(leafIndex)
+    let merkleProof
+
+    if ("siblings" in groupOrMerkleProof) {
+        merkleProof = groupOrMerkleProof
+    } else {
+        const leafIndex = groupOrMerkleProof.indexOf(identity.commitment)
+        merkleProof = groupOrMerkleProof.generateMerkleProof(leafIndex)
+    }
+
     const merkleProofLength = merkleProof.siblings.length
 
     if (merkleTreeDepth !== undefined) {

packages/proof/tests/index.test.ts

@@ -48,6 +48,15 @@ describe("Proof", () => {
             expect(typeof fullProof).toBe("object")
             expect(fullProof.merkleTreeRoot).toBe(group.root)
         }, 20000)
+
+        it("Should generate a Semaphore proof passing a Merkle proof instead of a group", async () => {
+            const group = new Group([BigInt(1), BigInt(2), identity.commitment])
+
+            fullProof = await generateProof(identity, group.generateMerkleProof(2), message, scope, treeDepth)
+
+            expect(typeof fullProof).toBe("object")
+            expect(fullProof.merkleTreeRoot).toBe(group.root)
+        }, 20000)
     })
 
     describe("# verifyProof", () => {