MetaMask · chakra-guy · Feb 27, 2026 · Feb 25, 2026 · Feb 25, 2026 · Feb 25, 2026
diff --git a/apps/integration-tests/src/end-to-end.integration.test.ts b/apps/integration-tests/src/end-to-end.integration.test.ts
@@ -3,7 +3,7 @@
 import { type ConnectionMode, type IKeyManager, type IKVStore, type KeyPair, type SessionRequest, SessionStore, WebSocketTransport } from "@metamask/mobile-wallet-protocol-core";
 import { DappClient, type OtpRequiredPayload } from "@metamask/mobile-wallet-protocol-dapp-client";
 import { WalletClient } from "@metamask/mobile-wallet-protocol-wallet-client";
-import { decrypt, encrypt, PrivateKey } from "eciesjs";
+import { decrypt, encrypt, PrivateKey, PublicKey } from "eciesjs";
 import { type Proxy, Toxiproxy } from "toxiproxy-node-client";
 import * as t from "vitest";
 import WebSocket from "ws";
@@ -32,6 +32,10 @@ export class KeyManager implements IKeyManager {
 		return { privateKey: new Uint8Array(privateKey.secret), publicKey: privateKey.publicKey.toBytes(true) };
 	}
 
+	validatePeerKey(key: Uint8Array): void {
+		PublicKey.fromHex(Buffer.from(key).toString("hex"));
+	}
+
 	async encrypt(plaintext: string, theirPublicKey: Uint8Array): Promise<string> {
 		const plaintextBuffer = Buffer.from(plaintext, "utf8");
 		const encryptedBuffer = encrypt(theirPublicKey, plaintextBuffer);

diff --git a/apps/load-tests/src/client/key-manager.ts b/apps/load-tests/src/client/key-manager.ts
@@ -21,6 +21,10 @@ export class MockKeyManager implements IKeyManager {
 		};
 	}
 
+	validatePeerKey(_key: Uint8Array): void {
+		// No-op: load tests don't use real crypto
+	}
+
 	async encrypt(plaintext: string, _theirPublicKey: Uint8Array): Promise<string> {
 		return Buffer.from(plaintext, "utf8").toString("base64");
 	}

diff --git a/apps/rn-demo/lib/KeyManager.ts b/apps/rn-demo/lib/KeyManager.ts
@@ -1,12 +1,16 @@
 import type { IKeyManager, KeyPair } from "@metamask/mobile-wallet-protocol-core";
-import { decrypt, encrypt, PrivateKey } from "eciesjs";
+import { decrypt, encrypt, PrivateKey, PublicKey } from "eciesjs";
 
 export class KeyManager implements IKeyManager {
 	generateKeyPair(): KeyPair {
 		const privateKey = new PrivateKey();
 		return { privateKey: new Uint8Array(privateKey.secret), publicKey: privateKey.publicKey.toBytes(true) };
 	}
 
+	validatePeerKey(key: Uint8Array): void {
+		PublicKey.fromHex(Buffer.from(key).toString("hex"));
+	}
+
 	async encrypt(plaintext: string, theirPublicKey: Uint8Array): Promise<string> {
 		const plaintextBuffer = Buffer.from(plaintext, "utf8");
 		const encryptedBuffer = encrypt(theirPublicKey, plaintextBuffer);

diff --git a/apps/web-demo/src/lib/KeyManager.ts b/apps/web-demo/src/lib/KeyManager.ts
@@ -1,12 +1,16 @@
 import type { IKeyManager, KeyPair } from "@metamask/mobile-wallet-protocol-core";
-import { decrypt, encrypt, PrivateKey } from "eciesjs";
+import { decrypt, encrypt, PrivateKey, PublicKey } from "eciesjs";
 
 export class KeyManager implements IKeyManager {
 	generateKeyPair(): KeyPair {
 		const privateKey = new PrivateKey();
 		return { privateKey: new Uint8Array(privateKey.secret), publicKey: privateKey.publicKey.toBytes(true) };
 	}
 
+	validatePeerKey(key: Uint8Array): void {
+		PublicKey.fromHex(Buffer.from(key).toString("hex"));
+	}
+
 	async encrypt(plaintext: string, theirPublicKey: Uint8Array): Promise<string> {
 		const plaintextBuffer = Buffer.from(plaintext, "utf8");
 		const encryptedBuffer = encrypt(theirPublicKey, plaintextBuffer);

diff --git a/packages/core/CHANGELOG.md b/packages/core/CHANGELOG.md
@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Add `validatePeerKey` method to `IKeyManager` interface for peer public key validation at handshake and resume time ([#70](https://github.com/MetaMask/mobile-wallet-protocol/pull/70))
+
+### Fixed
+
+- Guard against `NaN` in session expiry timestamps ([#70](https://github.com/MetaMask/mobile-wallet-protocol/pull/70))
+
 ## [0.3.1]
 
 ### Fixed

diff --git a/packages/core/src/base-client.integration.test.ts b/packages/core/src/base-client.integration.test.ts
@@ -1,7 +1,7 @@
 /** biome-ignore-all lint/suspicious/noExplicitAny: test code */
 /** biome-ignore-all lint/complexity/useLiteralKeys: test code */
 
-import { decrypt, encrypt, PrivateKey } from "eciesjs";
+import { decrypt, encrypt, PrivateKey, PublicKey } from "eciesjs";
 import { v4 as uuid } from "uuid";
 import * as t from "vitest";
 import WebSocket from "ws";
@@ -43,6 +43,10 @@ export class KeyManager implements IKeyManager {
 		return { privateKey: new Uint8Array(privateKey.secret), publicKey: privateKey.publicKey.toBytes(true) };
 	}
 
+	validatePeerKey(key: Uint8Array): void {
+		PublicKey.fromHex(Buffer.from(key).toString("hex"));
+	}
+
 	async encrypt(plaintext: string, theirPublicKey: Uint8Array): Promise<string> {
 		const plaintextBuffer = Buffer.from(plaintext, "utf8");
 		const encryptedBuffer = encrypt(theirPublicKey, plaintextBuffer);
@@ -170,7 +174,11 @@ t.describe("BaseClient", () => {
 			id: "session-to-disconnect",
 			channel,
 			keyPair: new KeyManager().generateKeyPair(),
-			theirPublicKey: new Uint8Array(33),
+			theirPublicKey: (() => {
+				const k = new Uint8Array(33);
+				k[0] = 0x02;
+				return k;
+			})(),
 			expiresAt: Date.now() + 60000,
 		};
 
@@ -198,7 +206,11 @@ t.describe("BaseClient", () => {
 			id: "expired-session",
 			channel,
 			keyPair: new KeyManager().generateKeyPair(),
-			theirPublicKey: new Uint8Array(33),
+			theirPublicKey: (() => {
+				const k = new Uint8Array(33);
+				k[0] = 0x02;
+				return k;
+			})(),
 			expiresAt: Date.now() - 1000, // Expired 1 second ago
 		};
 
@@ -220,7 +232,11 @@ t.describe("BaseClient", () => {
 			id: "expired-resume-session",
 			channel,
 			keyPair: new KeyManager().generateKeyPair(),
-			theirPublicKey: new Uint8Array(33),
+			theirPublicKey: (() => {
+				const k = new Uint8Array(33);
+				k[0] = 0x02;
+				return k;
+			})(),
 			expiresAt: Date.now() + 60000, // Valid session
 		};
 

diff --git a/packages/core/src/base-client.ts b/packages/core/src/base-client.ts
@@ -92,6 +92,7 @@ export abstract class BaseClient extends EventEmitter {
 		try {
 			const session = await this.sessionstore.get(sessionId);
 			if (!session) throw new SessionError(ErrorCode.SESSION_NOT_FOUND, "Session not found or expired");
+			this.keymanager.validatePeerKey(session.theirPublicKey);
 
 			this.session = session;
 			await this.transport.connect();

diff --git a/packages/core/src/domain/errors.ts b/packages/core/src/domain/errors.ts
@@ -15,6 +15,7 @@ export enum ErrorCode {
 
 	// Crypto errors
 	DECRYPTION_FAILED = "DECRYPTION_FAILED",
+	INVALID_KEY = "INVALID_KEY",
 
 	// Handshake errors
 	REQUEST_EXPIRED = "REQUEST_EXPIRED",

diff --git a/packages/core/src/domain/key-manager.ts b/packages/core/src/domain/key-manager.ts
@@ -7,4 +7,5 @@ export interface IKeyManager {
 	generateKeyPair(): KeyPair;
 	encrypt(plaintext: string, theirPublicKey: Uint8Array): Promise<string>;
 	decrypt(encryptedB64: string, myPrivateKey: Uint8Array): Promise<string>;
+	validatePeerKey(key: Uint8Array): void;
 }
diff --git a/packages/core/src/session-store/index.test.ts b/packages/core/src/session-store/index.test.ts
@@ -114,6 +114,27 @@ t.describe("SessionStore", () => {
 		t.expect(raw).toBeNull();
 	});
 
+	t.test("should reject a session with NaN expiresAt on set", async () => {
+		const session = createSession("nan-set", Number.NaN);
+		await t.expect(sessionstore.set(session)).rejects.toThrow("Cannot save expired session");
+	});
+
+	t.test("should treat a session with NaN expiresAt as expired on get", async () => {
+		const key = "session:nan-get";
+		const data = {
+			id: "nan-get",
+			channel: "test-channel",
+			keyPair: { publicKeyB64: Buffer.from(new Uint8Array(33).fill(1)).toString("base64"), privateKeyB64: Buffer.from(new Uint8Array(32).fill(1)).toString("base64") },
+			theirPublicKeyB64: Buffer.from(new Uint8Array(33).fill(2)).toString("base64"),
+			expiresAt: "not-a-number",
+		};
+		await kvstore.set(key, JSON.stringify(data));
+		await (kvstore as MockKVStore)["store"].set("sessions:master-list", JSON.stringify(["nan-get"]));
+
+		const retrieved = await sessionstore.get("nan-get");
+		t.expect(retrieved).toBeNull();
+	});
+
 	t.test("should garbage collect expired sessions", async () => {
 		const valid = createSession("valid", Date.now() + 10000);
 		const expired = createSession("expired", Date.now() - 10000);

diff --git a/packages/core/src/session-store/index.ts b/packages/core/src/session-store/index.ts
@@ -42,8 +42,8 @@ export class SessionStore implements ISessionStore {
 	 * @param session - The session to set.
 	 */
 	async set(session: Session): Promise<void> {
-		// Check if session is expired
-		if (session.expiresAt < Date.now()) {
+		// Check if session is expired (also rejects NaN)
+		if (Number.isNaN(session.expiresAt) || session.expiresAt < Date.now()) {
 			throw new SessionError(ErrorCode.SESSION_SAVE_FAILED, "Cannot save expired session");
 		}
 
@@ -80,14 +80,12 @@ export class SessionStore implements ISessionStore {
 		try {
 			const data: SerializableSession = JSON.parse(raw);
 
-			// Check if session is expired
-			if (data.expiresAt < Date.now()) {
-				// Session expired, clean it up
+			// Check if session is expired (handles NaN, non-number, and past timestamps)
+			if (typeof data.expiresAt !== "number" || !(data.expiresAt >= Date.now())) {
 				await this.delete(id);
 				return null;
 			}
 
-			// Deserialize back to Session
 			const session: Session = {
 				id: data.id,
 				channel: data.channel,

diff --git a/packages/core/src/transport/websocket/shared-centrifuge.test.ts b/packages/core/src/transport/websocket/shared-centrifuge.test.ts
@@ -7,7 +7,7 @@ t.describe("SharedCentrifuge Unit Tests", () => {
 		// Clean up any shared contexts after each test
 		// @ts-expect-error - accessing private property for cleanup
 		const contexts = SharedCentrifuge.contexts;
-		for (const [url, context] of contexts.entries()) {
+		for (const [_url, context] of contexts.entries()) {
 			// Clear any pending reconnect promises
 			context.reconnectPromise = null;
 			// Remove all event listeners to prevent unhandled errors

diff --git a/packages/dapp-client/CHANGELOG.md b/packages/dapp-client/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Validate peer public keys during handshake in both trusted and untrusted connection flows ([#70](https://github.com/MetaMask/mobile-wallet-protocol/pull/70))
+
 ## [0.2.2]
 
 ### Added

diff --git a/packages/dapp-client/src/client.integration.test.ts b/packages/dapp-client/src/client.integration.test.ts
@@ -1,6 +1,6 @@
 /** biome-ignore-all lint/suspicious/noExplicitAny: test code */
 import { type IKeyManager, type IKVStore, type KeyPair, type SessionRequest, SessionStore, WebSocketTransport } from "@metamask/mobile-wallet-protocol-core";
-import { decrypt, encrypt, PrivateKey } from "eciesjs";
+import { decrypt, encrypt, PrivateKey, PublicKey } from "eciesjs";
 import * as t from "vitest";
 import WebSocket from "ws";
 import { DappClient } from "./client";
@@ -26,6 +26,10 @@ export class KeyManager implements IKeyManager {
 		return { privateKey: new Uint8Array(privateKey.secret), publicKey: privateKey.publicKey.toBytes(true) };
 	}
 
+	validatePeerKey(key: Uint8Array): void {
+		PublicKey.fromHex(Buffer.from(key).toString("hex"));
+	}
+
 	async encrypt(plaintext: string, theirPublicKey: Uint8Array): Promise<string> {
 		const plaintextBuffer = Buffer.from(plaintext, "utf8");
 		const encryptedBuffer = encrypt(theirPublicKey, plaintextBuffer);

diff --git a/packages/dapp-client/src/client.ts b/packages/dapp-client/src/client.ts
@@ -118,6 +118,7 @@ export class DappClient extends BaseClient {
 		const context: IConnectionHandlerContext = {
 			transport: this.transport,
 			sessionstore: this.sessionstore,
+			keymanager: this.keymanager,
 			get session() {
 				return self.session;
 			},

diff --git a/packages/dapp-client/src/domain/connection-handler-context.ts b/packages/dapp-client/src/domain/connection-handler-context.ts
@@ -1,4 +1,4 @@
-import type { ClientState, HandshakeOfferPayload, ISessionStore, ITransport, ProtocolMessage, Session } from "@metamask/mobile-wallet-protocol-core";
+import type { ClientState, HandshakeOfferPayload, IKeyManager, ISessionStore, ITransport, ProtocolMessage, Session } from "@metamask/mobile-wallet-protocol-core";
 import type { OtpRequiredPayload } from "../client";
 
 /**
@@ -14,6 +14,7 @@ export interface IConnectionHandlerContext {
 	// Core Dependencies
 	readonly transport: ITransport;
 	readonly sessionstore: ISessionStore;
+	readonly keymanager: IKeyManager;
 
 	// Events
 	emit(event: "otp_required", payload: OtpRequiredPayload): void;

diff --git a/packages/dapp-client/src/handlers/trusted-connection-handler.test.ts b/packages/dapp-client/src/handlers/trusted-connection-handler.test.ts
@@ -22,6 +22,12 @@ function createMockDappHandlerContext(): IConnectionHandlerContext {
 			list: vi.fn(),
 			delete: vi.fn(),
 		},
+		keymanager: {
+			generateKeyPair: vi.fn(),
+			encrypt: vi.fn(),
+			decrypt: vi.fn(),
+			validatePeerKey: vi.fn(),
+		},
 		emit: vi.fn(),
 		once: vi.fn(),
 		off: vi.fn(),
@@ -56,7 +62,7 @@ t.describe("TrustedConnectionHandler", () => {
 		};
 		mockOffer = {
 			channelId: "secure-channel",
-			publicKeyB64: "cHVia2V5",
+			publicKeyB64: "Aqurq6urq6urq6urq6urq6urq6urq6urq6urq6urq6ur",
 		}; // No OTP for trusted flow
 	});
 

diff --git a/packages/dapp-client/src/handlers/trusted-connection-handler.ts b/packages/dapp-client/src/handlers/trusted-connection-handler.ts
@@ -82,10 +82,12 @@ export class TrustedConnectionHandler implements IConnectionHandler {
 	 * @returns The complete session object ready for use
 	 */
 	private _createFinalSession(session: Session, offer: HandshakeOfferPayload): Session {
+		const theirPublicKey = base64ToBytes(offer.publicKeyB64);
+		this.context.keymanager.validatePeerKey(theirPublicKey);
 		return {
 			...session,
 			channel: `session:${offer.channelId}`,
-			theirPublicKey: base64ToBytes(offer.publicKeyB64),
+			theirPublicKey,
 		};
 	}
 

diff --git a/packages/dapp-client/src/handlers/untrusted-connection-handler.test.ts b/packages/dapp-client/src/handlers/untrusted-connection-handler.test.ts
@@ -23,6 +23,12 @@ function createMockDappHandlerContext(): IConnectionHandlerContext {
 			list: vi.fn(),
 			delete: vi.fn(),
 		},
+		keymanager: {
+			generateKeyPair: vi.fn(),
+			encrypt: vi.fn(),
+			decrypt: vi.fn(),
+			validatePeerKey: vi.fn(),
+		},
 		emit: vi.fn(),
 		once: vi.fn(),
 		off: vi.fn(),
@@ -57,7 +63,7 @@ t.describe("UntrustedConnectionHandler", () => {
 		};
 		mockOffer = {
 			channelId: "secure-channel",
-			publicKeyB64: "cHVia2V5",
+			publicKeyB64: "Aqurq6urq6urq6urq6urq6urq6urq6urq6urq6urq6ur",
 			otp: "123456",
 			deadline: Date.now() + 1000,
 		};

diff --git a/packages/dapp-client/src/handlers/untrusted-connection-handler.ts b/packages/dapp-client/src/handlers/untrusted-connection-handler.ts
@@ -115,10 +115,12 @@ export class UntrustedConnectionHandler implements IConnectionHandler {
 	 * @returns The complete session object ready for use
 	 */
 	private _createFinalSession(session: Session, offer: HandshakeOfferPayload): Session {
+		const theirPublicKey = base64ToBytes(offer.publicKeyB64);
+		this.context.keymanager.validatePeerKey(theirPublicKey);
 		return {
 			...session,
 			channel: `session:${offer.channelId}`,
-			theirPublicKey: base64ToBytes(offer.publicKeyB64),
+			theirPublicKey,
 		};
 	}
 

diff --git a/packages/wallet-client/CHANGELOG.md b/packages/wallet-client/CHANGELOG.md
@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Validate peer public keys during session creation ([#70](https://github.com/MetaMask/mobile-wallet-protocol/pull/70))
+- Fix client stuck in CONNECTING state when session creation fails ([#70](https://github.com/MetaMask/mobile-wallet-protocol/pull/70))
+
 ## [0.2.2]
 
 ### Added

diff --git a/packages/wallet-client/src/client.integration.test.ts b/packages/wallet-client/src/client.integration.test.ts
@@ -1,7 +1,7 @@
 /** biome-ignore-all lint/suspicious/noExplicitAny: test code */
 import { type IKeyManager, type IKVStore, type KeyPair, type SessionRequest, SessionStore, WebSocketTransport } from "@metamask/mobile-wallet-protocol-core";
 import { bytesToBase64 } from "@metamask/utils";
-import { decrypt, encrypt, PrivateKey } from "eciesjs";
+import { decrypt, encrypt, PrivateKey, PublicKey } from "eciesjs";
 import * as t from "vitest";
 import WebSocket from "ws";
 import { WalletClient } from "./client";
@@ -27,6 +27,10 @@ export class KeyManager implements IKeyManager {
 		return { privateKey: new Uint8Array(privateKey.secret), publicKey: privateKey.publicKey.toBytes(true) };
 	}
 
+	validatePeerKey(key: Uint8Array): void {
+		PublicKey.fromHex(Buffer.from(key).toString("hex"));
+	}
+
 	async encrypt(plaintext: string, theirPublicKey: Uint8Array): Promise<string> {
 		const plaintextBuffer = Buffer.from(plaintext, "utf8");
 		const encryptedBuffer = encrypt(theirPublicKey, plaintextBuffer);