feat(proof): add function to calculate nullifier hash

Author: cedoor

packages/proof/README.md

@@ -67,7 +67,13 @@ yarn add @semaphore-protocol/identity @semaphore-protocol/group @semaphore-proto
 
 ## 📜 Usage
 
-\# **generateProof**(identity: _Identity_, group: _Group_ | _MerkleProof_, externalNullifier: _BigNumberish_, signal: _string_, snarkArtifacts?: _SnarkArtifacts_): Promise\<_SemaphoreFullProof_>
+\# **generateProof**(
+identity: _Identity_,
+group: _Group_ | _MerkleProof_,
+externalNullifier: _BytesLike | Hexable | number | bigint_,
+signal: _BytesLike | Hexable | number | bigint_,
+snarkArtifacts?: _SnarkArtifacts_
+): Promise\<_SemaphoreFullProof_>
 
 ```typescript
 import { Identity } from "@semaphore-protocol/identity"
@@ -98,3 +104,18 @@ import { verifyProof } from "@semaphore-protocol/proof"
 
 await verifyProof(fullProof, 20)
 ```
+
+\# **calculateNullifierHash**(
+identityNullifier: _bigint | number | string_,
+externalNullifier: \__BytesLike | Hexable | number | bigint_
+): Promise\<_boolean_>
+
+```typescript
+import { Identity } from "@semaphore-protocol/identity"
+import { calculateNullifierHash } from "@semaphore-protocol/proof"
+
+const identity = new Identity()
+const externalNullifier = utils.formatBytes32String("Topic")
+
+const nullifierHash = calculateNullifierHash(identity.nullifier, externalNullifier)
+```

packages/proof/package.json

@@ -30,8 +30,11 @@
         "access": "public"
     },
     "devDependencies": {
+        "@rollup/plugin-commonjs": "^24.1.0",
         "@rollup/plugin-json": "^5.0.1",
+        "@rollup/plugin-node-resolve": "^15.0.2",
         "ffjavascript": "^0.2.54",
+        "poseidon-lite": "^0.2.0",
         "rollup-plugin-cleanup": "^3.2.1",
         "rollup-plugin-typescript2": "^0.31.2",
         "typedoc": "^0.22.11"

packages/proof/rollup.config.ts

@@ -1,7 +1,9 @@
 import typescript from "rollup-plugin-typescript2"
+import commonjs from "@rollup/plugin-commonjs"
 import * as fs from "fs"
 import cleanup from "rollup-plugin-cleanup"
 import json from "@rollup/plugin-json"
+import { nodeResolve } from "@rollup/plugin-node-resolve"
 
 const pkg = JSON.parse(fs.readFileSync("./package.json", "utf-8"))
 const banner = `/**
@@ -25,6 +27,8 @@ export default {
             tsconfig: "./build.tsconfig.json",
             useTsconfigDeclarationDir: true
         }),
+        commonjs(),
+        nodeResolve(),
         cleanup({ comments: "jsdoc" }),
         json()
     ]

packages/proof/src/calculateNullifierHash.ts

@@ -0,0 +1,16 @@
+import { BytesLike, Hexable } from "@ethersproject/bytes"
+import { poseidon2 } from "poseidon-lite/poseidon2"
+import hash from "./hash"
+
+/**
+ * Given the identity nullifier and the external nullifier, it calculates nullifier hash.
+ * @param identityNullifier The identity nullifier.
+ * @param externalNullifier The external nullifier.
+ * @returns The nullifier hash.
+ */
+export default function calculateNullifierHash(
+    identityNullifier: number | bigint | string,
+    externalNullifier: BytesLike | Hexable | number | bigint
+): bigint {
+    return poseidon2([hash(externalNullifier), identityNullifier])
+}

packages/proof/src/index.test.ts

@@ -2,6 +2,7 @@ import { formatBytes32String } from "@ethersproject/strings"
 import { Group } from "@semaphore-protocol/group"
 import { Identity } from "@semaphore-protocol/identity"
 import { getCurveFromName } from "ffjavascript"
+import calculateNullifierHash from "./calculateNullifierHash"
 import generateProof from "./generateProof"
 import hash from "./hash"
 import packProof from "./packProof"
@@ -147,6 +148,14 @@ describe("Proof", () => {
         })
     })
 
+    describe("# calculateNullifierHash", () => {
+        it("Should calculate the nullifier hash correctly", async () => {
+            const nullifierHash = calculateNullifierHash(identity.nullifier, externalNullifier)
+
+            expect(fullProof.nullifierHash).toBe(nullifierHash.toString())
+        })
+    })
+
     describe("# packProof/unpackProof", () => {
         it("Should return a packed proof", async () => {
             const originalProof = unpackProof(fullProof.proof)

packages/proof/src/index.ts

@@ -1,5 +1,6 @@
 import generateProof from "./generateProof"
 import verifyProof from "./verifyProof"
+import calculateNullifierHash from "./calculateNullifierHash"
 
-export { generateProof, verifyProof }
+export { generateProof, verifyProof, calculateNullifierHash }
 export * from "./types"

yarn.lock

@@ -4110,6 +4110,25 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@rollup/plugin-commonjs@npm:^24.1.0":
+  version: 24.1.0
+  resolution: "@rollup/plugin-commonjs@npm:24.1.0"
+  dependencies:
+    "@rollup/pluginutils": ^5.0.1
+    commondir: ^1.0.1
+    estree-walker: ^2.0.2
+    glob: ^8.0.3
+    is-reference: 1.2.1
+    magic-string: ^0.27.0
+  peerDependencies:
+    rollup: ^2.68.0||^3.0.0
+  peerDependenciesMeta:
+    rollup:
+      optional: true
+  checksum: 42faafc9bc8e04d75c86bb50d693ebb9c5eee19bf9ab3c09780b872547d12ff5ea85cfec7da75f5176d0aa4b5233101f667f44b85b331450a7bb14c95180852e
+  languageName: node
+  linkType: hard
+
 "@rollup/plugin-json@npm:^5.0.1":
   version: 5.0.2
   resolution: "@rollup/plugin-json@npm:5.0.2"
@@ -4173,6 +4192,25 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@rollup/plugin-node-resolve@npm:^15.0.2":
+  version: 15.0.2
+  resolution: "@rollup/plugin-node-resolve@npm:15.0.2"
+  dependencies:
+    "@rollup/pluginutils": ^5.0.1
+    "@types/resolve": 1.20.2
+    deepmerge: ^4.2.2
+    is-builtin-module: ^3.2.1
+    is-module: ^1.0.0
+    resolve: ^1.22.1
+  peerDependencies:
+    rollup: ^2.78.0||^3.0.0
+  peerDependenciesMeta:
+    rollup:
+      optional: true
+  checksum: 328eafee06ff967a36441b55e77fbd0d4f599d256e5d1977800ee71915846c46bc1b6185df35c7b512ad2b4023b05b65a332be77b8b00b9d8a20f87d056b8166
+  languageName: node
+  linkType: hard
+
 "@rollup/plugin-replace@npm:^2.4.1":
   version: 2.4.2
   resolution: "@rollup/plugin-replace@npm:2.4.2"
@@ -4466,9 +4504,12 @@ __metadata:
     "@ethersproject/bytes": ^5.7.0
     "@ethersproject/keccak256": ^5.7.0
     "@ethersproject/strings": ^5.5.0
+    "@rollup/plugin-commonjs": ^24.1.0
     "@rollup/plugin-json": ^5.0.1
+    "@rollup/plugin-node-resolve": ^15.0.2
     "@zk-kit/incremental-merkle-tree": 0.4.3
     ffjavascript: ^0.2.54
+    poseidon-lite: ^0.2.0
     rollup-plugin-cleanup: ^3.2.1
     rollup-plugin-typescript2: ^0.31.2
     snarkjs: 0.4.13
@@ -12164,7 +12205,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"is-builtin-module@npm:^3.2.0":
+"is-builtin-module@npm:^3.2.0, is-builtin-module@npm:^3.2.1":
   version: 3.2.1
   resolution: "is-builtin-module@npm:3.2.1"
   dependencies: