react-native-passkey

Native Passkeys on iOS 15.0+ and Android API 28+ using React Native.

You can find an example backend for testing here.

Installation

Javascript

For the javascript part of the installation you need to run

npm install react-native-passkey

or

yarn add react-native-passkey

Native

For the native part of the installation you need to run

cd ios && pod install

in the root of your React Native project.

Configuration

iOS

There are iOS specific steps you need to go through in order to configure Passkey support. If you have already set up an associated domain for your application you can skip this step.

Set up an associated domain for your application (More info)

• You need to associate a domain with your application. On your webserver set up this route:

  GET https://<yourdomain>/.well-known/apple-app-site-association

• This route should serve a static JSON object containing your team id and bundle identifier. Example (replace XXXXXXXXXX with your team identifier and the rest with your bundle id, e.g. "H123456789.com.mtrx0.passkeyExample"):

  {
    "applinks": {},
    "webcredentials": {
      "apps": ["XXXXXXXXXX.YYY.YYYYY.YYYYYYYYYYYYYY"]
    },
    "appclips": {}
  }

• In XCode under Signing & Capabilities add a new Capability of type Associated Domains. Now add this and replace XXXXXX with your domain (e.g. apple.com)

  webcredentials:XXXXXX

Android

The Android specific configuration is similar to iOS. If you have already set up Digital Asset Links for your application you can skip this step.

Associate your app with a domain (More info)

• You need to associate a domain with your application. On your webserver set up this route:

  GET https://<yourdomain>/.well-known/assetlinks.json

• This route should serve a static JSON object containing the following information. Example (replace with your data, replace SHA_HEX_VALUE with the SHA256 fingerprints of your Android signing certificate)

  [{
    "relation": ["delegate_permission/common.get_login_creds"],
    "target": {
      "namespace": "android_app",
      "package_name": "com.example",
      "sha256_cert_fingerprints": [
        SHA_HEX_VALUE
      ]
    }
  }]

If you are having issues with your backend setup you can look at an example here.

Usage

Check if Passkeys are supported

import { Passkey } from 'react-native-passkey';

// Use this method to check if passkeys are supported on the device

const isSupported: boolean = Passkey.isSupported();

Creating a new Passkey

import { Passkey, PasskeyCreateResult } from 'react-native-passkey';

// Retrieve a valid FIDO2 attestation request from your server
// The challenge inside the request needs to be a base64URL encoded string
// There are plenty of libraries which can be used for this (e.g. fido2-lib)

try {
  // Call the `create` method with the retrieved request in JSON format
  // A native overlay will be displayed
  const result: PasskeyCreateResult = await Passkey.create(requestJson);

  // The `create` method returns a FIDO2 attestation result
  // Pass it to your server for verification
} catch (error) {
  // Handle Error...
}

Authenticating with existing Passkey

import { Passkey, PasskeyGetResult } from 'react-native-passkey';

// Retrieve a valid FIDO2 assertion request from your server
// The challenge inside the request needs to be a base64URL encoded string
// There are plenty of libraries which can be used for this (e.g. fido2-lib)

try {
  // Call the `get` method with the retrieved request in JSON format
  // A native overlay will be displayed
  const result: PasskeyGetResult = await Passkey.get(requestJson);

  // The `get` method returns a FIDO2 assertion result
  // Pass it to your server for verification
} catch (error) {
  // Handle Error...
}

Silent / Immediate Authentication

Use Passkey.getImmediate() to authenticate only when a credential is already available on the device, without surfacing the system modal when nothing matches. This is useful for opportunistic sign-in checks (e.g. on app launch or on a sign-in screen) where you do not want to interrupt the user with a credential picker if no passkey exists.

• iOS 16+: uses ASAuthorizationController.preferImmediatelyAvailableCredentials
• Android: uses the preferImmediatelyAvailableCredentials flag on GetCredentialRequest (Credential Manager)
• iOS < 16: falls back to a normal get() request (no silent behaviour available on the platform)

When no credential is available the call rejects with a NoCredentials error and no UI is shown. Handle this error to fall back to your usual sign-in flow.

import { Passkey } from 'react-native-passkey';

try {
  const result = await Passkey.getImmediate(requestJson);
  // Credential available — pass to your server
} catch (error) {
  if (error.error === 'NoCredentials') {
    // No passkey on device — fall back to password / OTP / etc.
  } else if (error.error === 'UserCancelled') {
    // User dismissed the sheet
  } else {
    // Handle other errors
  }
}

Error codes

The library normalises native error codes into the following set:

| error value | Meaning | | -------------------- | ---------------------------------------------------------------------- | | NotSupported | Passkeys are not supported on this device / OS version | | RequestFailed | Generic request failure (e.g. transport / network / invalid response) | | UserCancelled | User dismissed the system sheet | | InvalidChallenge | The provided challenge could not be decoded | | InvalidUserId | The provided user id could not be decoded (registration only) | | BadConfiguration | App is not configured correctly (associated domain / asset links) | | NoCredentials | No credential is available — also returned for silent getImmediate() | | CredentialAlreadyExists | A passkey already exists for this account on this device (registration) | | Interrupted | The operation was interrupted and may be retried | | TimedOut | The operation timed out | | UnknownError | Unknown / unmapped error |

Force Platform or Security Key (iOS-specific)

You can force users to register and authenticate using either a platform key, a security key (like Yubikey) or allow both using the following methods. This only works on iOS, Android will ignore these instructions.

Create Passkey

• Passkey.create() - Allow the user to choose between platform and security passkey
• Passkey.createPlatformKey() - Force the user to create a platform passkey
• Passkey.createSecurityKey() - Force the user to create a security passkey

Get Passkey

• Passkey.get() - Allow the user to choose between platform and security passkey
• Passkey.getPlatformKey() - Force the user to authenticate using a platform passkey
• Passkey.getSecurityKey() - Force the user to authenticate using a security passkey

Extensions

largeBlob

As of version 3.0 the largeBlob extension will work on iOS 17+ only.

Example

You can use the largeBlob extension to store a small amount of opaque data associated with the stored passkey.

Check for largeBlob support

During registration you can check whether the selected authenticator supports the largeBlob extension. Pass 'preferred' to allow registration to proceed even if the authenticator does not support it, or 'required' to fail if it does not.

// Request
{
  ...
  extensions: {
    largeBlob: {
      support: 'preferred' | 'required'
    }
  }
}

// Response
{
  ...
  clientExtensionResults: {
    largeBlob: {
      supported: boolean
    }
  }
}

Write data

If the largeBlob extension is supported you can write data to it during the assertion process. This does not work during registration.

// Request
{
  ...
  extensions: {
    largeBlob: {
      write: Uint8Array
    }
  }
}

// Response
{
  ...
  clientExtensionResults: {
    largeBlob: {
      written: true
    }
  }
}

Read data

After writing you can read the data on any following assertion.

// Request
{
  ...
  extensions: {
    largeBlob: {
      read: true
    }
  }
}

// Response
{
  ...
  clientExtensionResults: {
    largeBlob: {
      blob: number[]  // convert to Uint8Array if needed: new Uint8Array(blob)
    }
  }
}

You can find information on the largeBlob extension in the WebAuthn specification here.

Pseudo-Random Function (PRF)

As of version 3.3 the PRF extension will work for Android and iOS 18+.

On Android, binary extension inputs are sent to Credential Manager as standard WebAuthn JSON. You can pass PRF salts as a Uint8Array, ArrayBuffer, number[], or a Base64URL string; the library normalizes them to Base64URL before calling the native Android API. This avoids Android rejecting otherwise valid PRF creation requests with No create options available.

Example

You can use the PRF extension to retrieve a secret which allows for various use cases like encryption of user data.

During registration you can either pass in an empty object (this will check for PRF support) or a salt (with an optional second) to retrieve the secret.

Check for PRF support

// Request
{
  ...
  extensions: {
    prf: {}
  }
}

// Response
{
  ...
  clientExtensionResults: {
    prf: {
      enabled: boolean
      results: {}
    }
  }
}

Retrieve secret

You can do this either when creating or when asserting the passkey.

// Request
{
  ...
  extensions: {
    prf: {
      eval: {
        first: Uint8Array | ArrayBuffer | number[] | string
        second: Uint8Array | ArrayBuffer | number[] | string // optional
      }
    }
  }
}

// Response
{
  ...
  clientExtensionResults: {
    prf: {
      enabled: true
      results: {
          first: 'Be3rf7AK8fwisd9vO13uqaP92XA24jKMSUaEaMclWIk=',
          second: 'jbVCsIGJvtSWv6LRG3fHpUaG/BvT75b8ZLRAuLBNUpk='
      },
    }
  }
}

You can also use evalByCredential to retrieve secrets for specific credentials. You can read more in the WebAuthn specification here.

Contributing

See the contributing guide to learn how to contribute to the repository and the development workflow.

License

MIT