expo-passkey
Version:
Passkey authentication for Expo apps with Better Auth integration
166 lines • 5.51 kB
JavaScript
/**
* @file WebAuthn utility functions
* @module expo-passkey/client/utils/webauthn
*/
import { Platform } from "react-native";
// Store device info locally
let deviceInfo = null;
/**
* Checks if the device supports WebAuthn
*/
export function checkWebAuthnSupport() {
try {
// iOS 16+ supports WebAuthn
if (Platform.OS === "ios") {
const version = parseInt(Platform.Version, 10);
const isSupported = !isNaN(version) && version >= 16;
return {
isSupported,
platformDetails: {
platform: Platform.OS,
version: Platform.Version,
},
error: isSupported ? null : "Requires iOS 16 or later",
};
}
// Android API level 29+ (Android 10+) supports WebAuthn
if (Platform.OS === "android") {
// Try to use stored deviceInfo if available
const apiLevel = deviceInfo?.platformDetails?.apiLevel;
// Default to checking platform version if apiLevel is not available
const majorVersion = Number(String(Platform.Version).split(".")[0]);
// Android 10 is version 29
const isSupported = (typeof apiLevel === "number" && apiLevel >= 29) || majorVersion >= 10;
return {
isSupported,
platformDetails: {
platform: Platform.OS,
version: Platform.Version,
apiLevel: apiLevel || null,
},
error: isSupported
? null
: "Requires Android 10 (API level 29) or later",
};
}
return {
isSupported: false,
platformDetails: {
platform: Platform.OS,
version: Platform.Version,
},
error: "Unsupported platform",
};
}
catch (error) {
return {
isSupported: false,
platformDetails: {
platform: Platform.OS,
version: Platform.Version,
},
error: error instanceof Error
? error.message
: "Unknown error checking WebAuthn support",
};
}
}
/**
* Create registration options for WebAuthn
*/
export function createRegistrationOptions(challenge, userId, userName, displayName, rpId, rpName, options) {
// Convert userId to a byte array, then to base64url
const userIdBuffer = new TextEncoder().encode(userId);
const userIdBase64 = bufferToBase64url(userIdBuffer.buffer);
// Default authenticator selection to require platform authenticator (biometric)
const defaultAuthenticatorSelection = {
authenticatorAttachment: "platform",
userVerification: "required",
residentKey: "required",
};
// Create options
return {
rp: {
id: rpId,
name: rpName,
},
user: {
id: userIdBase64,
name: userName,
displayName: displayName,
},
challenge,
pubKeyCredParams: [
// ES256 (Elliptic Curve P-256 with SHA-256)
{ type: "public-key", alg: -7 },
// RS256 (RSASSA-PKCS1-v1_5 using SHA-256)
{ type: "public-key", alg: -257 },
],
timeout: options?.timeout ?? 60000, // 1 minute
authenticatorSelection: options?.authenticatorSelection ?? defaultAuthenticatorSelection,
attestation: options?.attestation ?? "none",
excludeCredentials: options?.excludeCredentials?.map((cred) => ({
type: "public-key",
id: cred.id,
transports: ["internal"],
})) ?? [],
};
}
/**
* Create authentication options for WebAuthn
*/
export function createAuthenticationOptions(challenge, rpId, options) {
return {
challenge,
rpId,
timeout: options?.timeout ?? 60000, // 1 minute
userVerification: options?.userVerification ?? "required",
...(options?.allowCredentials && options.allowCredentials.length > 0
? {
allowCredentials: options.allowCredentials.map((cred) => ({
type: "public-key",
id: cred.id,
transports: ["internal"],
})),
}
: {}),
};
}
/**
* Convert ArrayBuffer to base64url string
*/
export function bufferToBase64url(buffer) {
const bytes = new Uint8Array(buffer);
let str = "";
for (const byte of bytes) {
str += String.fromCharCode(byte);
}
// Convert binary string to base64
const base64 = btoa(str);
// Convert base64 to base64url
return base64.replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
}
/**
* Convert base64url string to ArrayBuffer
*/
export function base64urlToBuffer(base64url) {
// Convert base64url to base64
let base64 = base64url.replace(/-/g, "+").replace(/_/g, "/");
// Add padding if needed
while (base64.length % 4 !== 0) {
base64 += "=";
}
const binary = atob(base64);
const bytes = new Uint8Array(binary.length);
for (let i = 0; i < binary.length; i++) {
bytes[i] = binary.charCodeAt(i);
}
return bytes.buffer;
}
/**
* Sets the device info reference for internal use
*/
export function setDeviceInfo(info) {
deviceInfo = info;
}
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