refactor(identity): add identity commitment attribute

Author: cedoor

packages/identity/README.md

@@ -76,7 +76,7 @@ yarn add @semaphore-protocol/identity
 import { Identity } from "@semaphore-protocol/identity"
 
 // The identity will be generated randomly.
-const { privateKey, publicKey } = new Identity()
+const { privateKey, publicKey, identityCommitment } = new Identity()
 
 // Alternatively, you can pass your private key.
 const identity = new Identity("your-private-key")
@@ -106,7 +106,7 @@ const signature = identity.signMessage(message)
 identity.verifySignature(message, signature)
 ```
 
-\# **Identity.verifySignature**(message: _BigNumberish_, signature: _Signature_, publicKey: _BigNumber_ | _Point_): _boolean_
+\# **Identity.verifySignature**(message: _BigNumberish_, signature: _Signature_, publicKey: _Point_): _boolean_
 
 ```typescript
 import { Identity } from "@semaphore-protocol/identity"

packages/identity/package.json

@@ -36,6 +36,7 @@
         "rollup-plugin-typescript2": "^0.31.2"
     },
     "dependencies": {
-        "@zk-kit/eddsa-poseidon": "0.4.1"
+        "@zk-kit/eddsa-poseidon": "0.4.1",
+        "poseidon-lite": "^0.2.0"
     }
 }

packages/identity/src/identity.test.ts

@@ -8,19 +8,18 @@ describe("Identity", () => {
             const identity = new Identity()
 
             expect(Buffer.isBuffer(identity.privateKey)).toBeTruthy()
-            expect(typeof identity.publicKey).toBe("string")
             expect(typeof identity.secretScalar).toBe("string")
-            expect(identity.unpackedPublicKey).toHaveLength(2)
+            expect(identity.publicKey).toHaveLength(2)
+            expect(typeof identity.identityCommitment).toBe("string")
         })
 
         it("Should create deterministic identities from a secret (private key)", () => {
             const identity = new Identity(privateKey)
 
             expect(typeof identity.privateKey).toBe("string")
-            expect(typeof identity.publicKey).toBe("string")
             expect(typeof identity.secretScalar).toBe("string")
-            expect(identity.unpackedPublicKey).toHaveLength(2)
-            expect(typeof identity.unpackedPublicKey[0]).toBe("string")
+            expect(identity.publicKey).toHaveLength(2)
+            expect(typeof identity.identityCommitment).toBe("string")
         })
     })
 
@@ -51,15 +50,14 @@ describe("Identity", () => {
             const signature = identity.signMessage("message")
 
             expect(Identity.verifySignature("message", signature, identity.publicKey)).toBeTruthy()
-            expect(Identity.verifySignature("message", signature, BigInt(identity.publicKey))).toBeTruthy()
         })
 
         it("Should verify an external signature with an unpacked public key", () => {
             const identity = new Identity(privateKey)
 
             const signature = identity.signMessage("message")
 
-            expect(Identity.verifySignature("message", signature, identity.unpackedPublicKey)).toBeTruthy()
+            expect(Identity.verifySignature("message", signature, identity.publicKey)).toBeTruthy()
         })
     })
 })

packages/identity/src/identity.ts

@@ -1,22 +1,20 @@
 import {
-    BigNumber,
     BigNumberish,
     Point,
     Signature,
     derivePublicKey,
     deriveSecretScalar,
-    packPublicKey,
     signMessage,
-    unpackPublicKey,
     verifySignature
 } from "@zk-kit/eddsa-poseidon"
 import { randomBytes } from "crypto"
+import { poseidon2 } from "poseidon-lite/poseidon2"
 
 export default class Identity {
     private _privateKey: BigNumberish
     private _secretScalar: string
-    private _unpackedPublicKey: Point<string>
-    private _publicKey: string
+    private _publicKey: Point<string>
+    private _identityCommitment: string
 
     /**
      * Initializes the class attributes based on the parameters.
@@ -26,9 +24,9 @@ export default class Identity {
         this._privateKey = privateKey
         this._secretScalar = deriveSecretScalar(privateKey)
 
-        this._unpackedPublicKey = derivePublicKey(privateKey)
+        this._publicKey = derivePublicKey(privateKey)
 
-        this._publicKey = packPublicKey(this._unpackedPublicKey) as string
+        this._identityCommitment = poseidon2(this._publicKey).toString()
     }
 
     /**
@@ -51,31 +49,27 @@ export default class Identity {
      * Returns the public key.
      * @returns The public key.
      */
-    public get publicKey(): string {
+    public get publicKey(): Point<string> {
         return this._publicKey
     }
 
     /**
-     * Returns the unpacked public key.
-     * @returns The unpacked public key.
+     * Returns the identity commitment.
+     * @returns The identity commitment.
      */
-    public get unpackedPublicKey(): Point<string> {
-        return this._unpackedPublicKey
+    public get identityCommitment(): string {
+        return this._identityCommitment
     }
 
     public signMessage(message: BigNumberish): Signature<string> {
         return signMessage(this.privateKey, message)
     }
 
     public verifySignature(message: BigNumberish, signature: Signature): boolean {
-        return verifySignature(message, signature, this._unpackedPublicKey)
+        return verifySignature(message, signature, this._publicKey)
     }
 
-    static verifySignature(message: BigNumberish, signature: Signature, publicKey: BigNumber | Point): boolean {
-        if (typeof publicKey === "string" || typeof publicKey === "bigint") {
-            publicKey = unpackPublicKey(publicKey)
-        }
-
+    static verifySignature(message: BigNumberish, signature: Signature, publicKey: Point): boolean {
         return verifySignature(message, signature, publicKey)
     }
 }

yarn.lock

@@ -8492,6 +8492,7 @@ __metadata:
     "@rollup/plugin-commonjs": ^24.0.1
     "@rollup/plugin-node-resolve": ^15.0.1
     "@zk-kit/eddsa-poseidon": 0.4.1
+    poseidon-lite: ^0.2.0
     rollup-plugin-cleanup: ^3.2.1
     rollup-plugin-typescript2: ^0.31.2
   languageName: unknown