Add support for parseCreationOptionsFromJSON and parseRequestOptionsFromJSON (issue #39)

.changeset/feat-parse-json-options-39.md

@@ -0,0 +1,32 @@
+---
+"react-native-passkeys": minor
+---
+
+Add support for parseCreationOptionsFromJSON and parseRequestOptionsFromJSON across all platforms
+
+This change exports `parseCreationOptionsFromJSON` and `parseRequestOptionsFromJSON` functions, enabling cross-platform JSON-to-WebAuthn conversion following the WebAuthn Level 3 specification.
+
+**New Exports:**
+- `parseCreationOptionsFromJSON(json)` - Converts PublicKeyCredentialCreationOptionsJSON to native format
+- `parseRequestOptionsFromJSON(json)` - Converts PublicKeyCredentialRequestOptionsJSON to native format
+
+**Implementation:**
+- Added comprehensive JSON conversion utilities matching Chromium's implementation (`src/utils/json.ts`)
+- Web platform uses browser's native `PublicKeyCredential.parseCreationOptionsFromJSON` and `parseRequestOptionsFromJSON`
+- Native platforms (iOS/Android) already accept JSON format, these utilities provide validation and type safety
+- Handles all credential fields including challenge, user, excludeCredentials, allowCredentials
+- Supports all WebAuthn extensions (PRF, largeBlob, credProps)
+- Proper base64url encoding/decoding for ArrayBuffer fields
+
+**Additional utilities:**
+- Added `isJSONFormat` utility to detect JSON vs binary format
+- Extracted extension warning logic to separate module
+
+**Benefits:**
+- ✨ Cross-platform API consistency
+- 📋 WebAuthn Level 3 spec compliance
+- 🔧 Type-safe JSON conversion with helpful error messages
+- 🎯 ~100 fewer lines in web module through code consolidation
+- 🚀 Native browser methods on web for optimal performance
+
+Fixes #39

src/ReactNativePasskeysModule.web.ts

@@ -1,26 +1,25 @@
 import { NotSupportedError } from "./errors";
-import { base64URLStringToBuffer, bufferToBase64URLString } from "./utils/base64";
+import { bufferToBase64URLString } from "./utils/base64";
 
 import type {
 	AuthenticationCredential,
-	AuthenticationExtensionsClientInputs,
 	AuthenticationExtensionsClientOutputs,
-	AuthenticationExtensionsClientOutputsJSON,
 	AuthenticationResponseJSON,
 	PublicKeyCredentialCreationOptionsJSON,
 	PublicKeyCredentialRequestOptionsJSON,
 	RegistrationCredential,
 	CreationResponse,
 } from "./ReactNativePasskeys.types";
-import { normalizePRFInputs } from "./utils/prf";
+import { authenticationExtensionsClientOutputsToJSON } from "./utils/json";
+import { warnUserOfMissingWebauthnExtensions } from "./utils/warn-user-of-missing-webauthn-extensions";
 
 export default {
 	get name(): string {
 		return "ReactNativePasskeys";
 	},
 
 	isAutoFillAvalilable(): Promise<boolean> {
-		return window.PublicKeyCredential.isConditionalMediationAvailable?.() ?? Promise.resolve(false);
+		return PublicKeyCredential.isConditionalMediationAvailable?.() ?? Promise.resolve(false);
 	},
 
 	isSupported() {
@@ -38,28 +37,13 @@ export default {
 
 		const credential = (await navigator.credentials.create({
 			signal,
-			publicKey: {
-				...request,
-				challenge: base64URLStringToBuffer(request.challenge),
-				user: { ...request.user, id: base64URLStringToBuffer(request.user.id) },
-				excludeCredentials: request.excludeCredentials?.map((credential) => ({
-					...credential,
-					id: base64URLStringToBuffer(credential.id),
-					// TODO: remove the override when typescript has updated webauthn types
-					transports: (credential.transports ?? undefined) as AuthenticatorTransport[] | undefined,
-				})),
-				extensions: {
-					...request.extensions,
-					prf: normalizePRFInputs(request),
-				},
-			},
+			publicKey: PublicKeyCredential.parseCreationOptionsFromJSON(request),
 		})) as RegistrationCredential;
 
 		// TODO: remove the override when typescript has updated webauthn types
 		const extensions =
 			credential?.getClientExtensionResults() as AuthenticationExtensionsClientOutputs;
 		warnUserOfMissingWebauthnExtensions(request.extensions, extensions);
-		const { largeBlob, prf, credProps, ...clientExtensionResults } = extensions;
 
 		if (!credential) return null;
 
@@ -78,25 +62,7 @@ export default {
 			},
 			authenticatorAttachment: undefined,
 			type: "public-key",
-			clientExtensionResults: {
-				...clientExtensionResults,
-				...(largeBlob && {
-					largeBlob: {
-						...largeBlob,
-						blob: largeBlob?.blob ? bufferToBase64URLString(largeBlob.blob) : undefined,
-					},
-				}),
-				...(prf?.results && {
-					prf: {
-						enabled: prf.enabled,
-						results: {
-							first: bufferToBase64URLString(prf.results.first),
-							second: prf.results.second ? bufferToBase64URLString(prf.results.second) : undefined,
-						},
-					},
-				}),
-				...(credProps && { credProps }),
-			} satisfies AuthenticationExtensionsClientOutputsJSON,
+			clientExtensionResults: authenticationExtensionsClientOutputsToJSON(extensions),
 		};
 	},
 
@@ -112,43 +78,18 @@ export default {
 		const credential = (await navigator.credentials.get({
 			mediation,
 			signal,
-			publicKey: {
-				...request,
-				extensions: {
-					...request.extensions,
-					prf: normalizePRFInputs(request),
-					/**
-					 * the navigator interface doesn't have a largeBlob property
-					 * as it may not be supported by all browsers
-					 *
-					 * browsers that do not support the extension will just ignore the property so it's safe to include it
-					 *
-					 * @ts-expect-error:*/
-					largeBlob: request.extensions?.largeBlob?.write
-						? {
-								...request.extensions?.largeBlob,
-								write: base64URLStringToBuffer(request.extensions.largeBlob.write),
-							}
-						: request.extensions?.largeBlob,
-				},
-				challenge: base64URLStringToBuffer(request.challenge),
-				allowCredentials: request.allowCredentials?.map((credential) => ({
-					...credential,
-					id: base64URLStringToBuffer(credential.id),
-					// TODO: remove the override when typescript has updated webauthn types
-					transports: (credential.transports ?? undefined) as AuthenticatorTransport[] | undefined,
-				})),
-			},
+			publicKey: PublicKeyCredential.parseRequestOptionsFromJSON(request),
 		})) as AuthenticationCredential;
 
 		// TODO: remove the override when typescript has updated webauthn types
 		const extensions =
 			credential?.getClientExtensionResults() as AuthenticationExtensionsClientOutputs;
 		warnUserOfMissingWebauthnExtensions(request.extensions, extensions);
-		const { largeBlob, prf, credProps, ...clientExtensionResults } = extensions;
 
 		if (!credential) return null;
 
+		if (credential.toJSON) return credential.toJSON() as AuthenticationResponseJSON;
+
 		return {
 			id: credential.id,
 			rawId: credential.id,
@@ -161,43 +102,8 @@ export default {
 					: undefined,
 			},
 			authenticatorAttachment: undefined,
-			clientExtensionResults: {
-				...clientExtensionResults,
-				...(largeBlob && {
-					largeBlob: {
-						...largeBlob,
-						blob: largeBlob?.blob ? bufferToBase64URLString(largeBlob.blob) : undefined,
-					},
-				}),
-				...(prf?.results && {
-					prf: {
-						results: {
-							first: bufferToBase64URLString(prf.results.first),
-							second: prf.results.second ? bufferToBase64URLString(prf.results.second) : undefined,
-						},
-					},
-				}),
-				...(credProps && { credProps }),
-			} satisfies AuthenticationExtensionsClientOutputsJSON,
+			clientExtensionResults: authenticationExtensionsClientOutputsToJSON(extensions),
 			type: "public-key",
 		};
 	},
-};
-
-/**
- *  warn the user about extensions that they tried to use that are not supported
- */
-const warnUserOfMissingWebauthnExtensions = (
-	requestedExtensions: AuthenticationExtensionsClientInputs | undefined,
-	clientExtensionResults: AuthenticationExtensionsClientOutputs | undefined,
-) => {
-	if (clientExtensionResults) {
-		for (const key in requestedExtensions) {
-			if (typeof clientExtensionResults[key] === "undefined") {
-				alert(
-					`Webauthn extension ${key} is undefined -- your browser probably doesn't know about it`,
-				);
-			}
-		}
-	}
-};
+};

src/index.ts

@@ -50,3 +50,9 @@ export async function get(
 ): Promise<AuthenticationResponseJSON | null> {
 	return await ReactNativePasskeysModule.get(request);
 }
+
+// Export JSON conversion utilities for cross-platform use
+export {
+	publicKeyCredentialCreationOptionsFromJSON as parseCreationOptionsFromJSON,
+	publicKeyCredentialRequestOptionsFromJSON as parseRequestOptionsFromJSON,
+} from './utils/json';

src/utils/is-json-format.ts

@@ -0,0 +1,34 @@
+class ArrayBufferFoundError extends Error {
+  constructor() {
+    super("ArrayBuffer found");
+    this.name = "ArrayBufferFoundError";
+  }
+}
+
+/**
+ * Helper to detect if input is JSON format (base64url strings) vs binary format (ArrayBuffers).
+ *
+ * This determines whether we can use the static method `parseCreationOptionsFromJSON`
+ *
+ * Uses JSON.stringify with a custom replacer to efficiently detect nested ArrayBuffers or TypedArrays.
+ * Throws early when binary data is found to avoid traversing the entire object tree.
+ *
+ * @param input - The credential options object to check
+ * @returns true if the input is in JSON format (no ArrayBuffers), false if it contains binary data
+ */
+export function isJSONFormat(input: unknown): boolean {
+  if (typeof input !== 'object' || input === null) return true;
+
+  try {
+    JSON.stringify(input, (_key, value) => {
+      if (value instanceof ArrayBuffer || ArrayBuffer.isView(value)) 
+        throw new ArrayBufferFoundError();
+      return value;
+    });
+    return true;
+  } catch (e) {
+    if (e instanceof ArrayBufferFoundError) return false;
+    // Re-throw any other error
+    throw e; 
+  }
+}