Certification and electronic signatures

Use @react-native-kakao/cert for Kakao certification login and abbreviated signatures. Certification login combines Kakao Login with an electronic signature using a Kakao certificate. An approved Kakao app and server integration are required.

Product	Function	Platforms
K2100	Certification login through KakaoTalk or Kakao Account.	Android, iOS, web authorization redirect
K2220	Certification login through KakaoTalk, followed by signatures during a session.	Android, iOS
K3220	Signing through KakaoTalk, followed by signatures during a session.	Android, iOS

Your server issues settlement IDs, prepares and verifies signatures, and retrieves signer information. Keep server secrets out of the app. Follow the official K2100, K2220, and K3220 integration guides.

Installation and callbacks

Install the packages below and initialize Core.

yarn add @react-native-kakao/core @react-native-kakao/user @react-native-kakao/cert

For Expo, enable certification callbacks in the Core plugin and regenerate the native projects.

[
  "@react-native-kakao/core",
  {
    "nativeAppKey": "NATIVE_APP_KEY",
    "android": {
      "authCodeHandlerActivity": true,
      "certServiceHandlerActivity": true
    },
    "ios": {
      "handleKakaoOpenUrl": true,
      "handleKakaoCertOpenUrl": true
    }
  }
]

Without Expo on Android, register com.kakao.sdk.cert.CertServiceHandlerActivity with android:exported="true" alongside the login callback. Add an intent filter with the VIEW action, DEFAULT and BROWSABLE categories, and the kakaoNATIVE_APP_KEY://cert URI.

On iOS, retain the Kakao Login URL scheme and callback, and add kakaotalk to LSApplicationQueriesSchemes. Forward certification URLs from AppDelegate to the SDK. Insert this Swift handler before existing URL handling. In ObjC++, import <RNCKakaoCert/RNCKakaoCertUtil.h> and call the same two class methods.

import RNCKakaoCert

if RNCKakaoCertUtil.isKakaoTalkSignReturnUrl(url) {
  return RNCKakaoCertUtil.handleOpen(url)
}

Certification login

For K2100, pass the settlement ID and signing data supplied by your server. Choose the KakaoTalk or Kakao Account method for the required authentication flow. Check KakaoTalk availability with isKakaoTalkLoginAvailable() from @react-native-kakao/user.

import { certLoginWithKakaoAccount, certLoginWithKakaoTalk } from '@react-native-kakao/cert';

const result = await certLoginWithKakaoTalk({
  certType: 'K2100',
  settleId,
  signData,
  identifyItems: ['ci', 'name'],
});

const accountResult = await certLoginWithKakaoAccount({
  certType: 'K2100',
  settleId,
  signData,
  loginHint,
});

Both methods return { token, txId }. The token uses the same KakaoLoginToken type as regular login. Your server uses txId to verify the signature. For K2220, pass the server-prepared transaction ID to certLoginWithKakaoTalk({ certType: 'K2220', txId }). Kakao Account login supports K2100 only.

Option	Behavior
prompts	Accepts Login, Create, and SelectAccount. The SDK adds its certification prompt.
identifyItems	Requests signer information using ci, name, birthday, and phone_number.
nonce	Random string used to verify the OpenID Connect ID token.
channelPublicIds, serviceTerms	Channels and terms requested during KakaoTalk certification login.
ios.launchMethod	Switches to KakaoTalk through UniversalLink or CustomScheme. Defaults to UniversalLink.
android.requestCode	KakaoTalk certification login request code passed to the Android SDK. Accepts a 32-bit integer from -2147483648 to 2147483647; defaults to the SDK value when omitted. SDK 2.25.1 uses it only in diagnostic logs, without distinguishing result callbacks.
android.channelPublicIds, android.serviceTerms	Kakao Account certification login options. The public iOS account SDK does not support them.

The pinned native SDKs expose only the four signer-information items listed above. Other items are excluded from the type.

Exchange a certification authorization code

On iOS, issueCertTokenWithCode() exchanges a certification authorization code from a separate flow for { token, txId } and stores the tokens in the SDK. It requires a certification code for an approved app. The result uses the same KakaoCertTokenInfo as certification login.

import { issueCertTokenWithCode } from '@react-native-kakao/cert';

const result = await issueCertTokenWithCode({
  code: certificationAuthorizationCode,
  codeVerifier,
  redirectUri,
});

codeVerifier is the PKCE verification value from that authorization request; pass the same value if PKCE was used. Omitting redirectUri uses the initialized iOS SDK's default URI. An explicit URI must match the authorization request. Android and web reject this API with Package-UnsupportedPlatform.

For web, exchange certification authorization codes through REST on your service server. Use the returned tx_id to verify the signature on the server. Follow the official K2100 guide for the integration sequence.

Keys, sessions, and abbreviated signatures

For K2220 and K3220, the SDK stores a temporary key pair on the device. This example sends the K2220 public key to your server, completes certification login, and retrieves the session. Implement prepareOnServer() and verifyOnServer() on your own server.

import {
  getPublicKey, certLoginWithKakaoTalk, fetchSessionInfo,
  getSessionInfo, isValidSession, reducedSign, deleteKeyPair,
} from '@react-native-kakao/cert';

const certType = 'K2220';
const publicKey = await getPublicKey({ certType });
if (!publicKey) throw new Error('Public key unavailable');
const { txId } = await prepareOnServer(publicKey);
await certLoginWithKakaoTalk({ certType, txId });
await verifyOnServer(txId);
const session = await fetchSessionInfo({ certType, txId });

if (await isValidSession({ certType })) {
  const signature = await reducedSign({ certType, data });
}

const cachedSession = await getSessionInfo({ certType });
await deleteKeyPair({ certType });

getPublicKey() retrieves or creates the public key and returns undefined when the SDK cannot provide one. Private keys stay inside the SDK. getSessionInfo() reads the stored session and returns undefined when none exists. fetchSessionInfo() retrieves a session from the server and stores it in the SDK. Sessions contain { userId?, sessionStartAt, sessionEndAt }, with timestamps in Unix seconds.

For K3220, check isKakaoTalkSignAvailable() and call signWithKakaoTalk({ txId, targetAppKey? }). Its response contains { txId, requestedAt?, requestExpiredAt?, signedAt? }, with timestamps in Unix seconds. Then call fetchSessionInfoByAppKey({ certType: 'K3220', txId, targetAppKey? }). The remaining local key and session methods work as for K2220.

Signing fails if a session is missing or expired. deleteKeyPair() deletes the selected product's key pair and session; its Promise<void> resolves without a success value. Follow the official recovery sequence when the SDK reports an error.

On iOS, signWithKakaoTalk() rejects a new request while another is pending. Wait for the first request to finish before calling it again.

Web certification login

On web, authorizeForCertWeb() starts the K2100 certification login redirect. Load the JavaScript SDK and initialize Core for web.

import { authorizeForCertWeb } from '@react-native-kakao/cert';

await authorizeForCertWeb({
  redirectUri,
  settleId,
  signData,
  state,
  identifyItems: ['ci'],
});

The returned Promise<void> does not signal completed authentication or token issuance. Handle the authorization code and signature verification after the redirect. The wrapper converts prompt, scope, serviceTerms, and identifyItems arrays into comma-separated strings. It also accepts throughTalk, throughSyncplugin, channelPublicId, deviceType, loginHint, and nonce.

On web, isKakaoTalkSignAvailable() returns false. Native certification login, keys, sessions, and abbreviated signatures reject with Package-UnsupportedPlatform. Calling authorizeForCertWeb() on Android or iOS rejects with the same code.