// Get generated token from server-side
final String authenticatedQueryToServerSide =
        "eyJraWQiOiI3MGI0NDdlMzIxZjNhMGZkIiwidHlwIjoiSldUIiwiYWxnIjoiVkVEUzUxMiIsImN0eSI6InZpcmdpbC1qd3Q7dj0xIn0.eyJleHAiOjE1MTg2OTg5MTcsImlzcyI6InZpcmdpbC1iZTAwZTEwZTRlMWY0YmY1OGY5YjRkYzg1ZDc5Yzc3YSIsInN1YiI6ImlkZW50aXR5LUFsaWNlIiwiaWF0IjoxNTE4NjEyNTE3fQ.MFEwDQYJYIZIAWUDBAIDBQAEQP4Yo3yjmt8WWJ5mqs3Yrqc_VzG6nBtrW2KIjP-kxiIJL_7Wv0pqty7PDbDoGhkX8CJa6UOdyn3rBWRvMK7p7Ak";

// Setup AccessTokenProvider
CallbackJwtProvider.GetTokenCallback getTokenCallback = new CallbackJwtProvider.GetTokenCallback() {

        @Override
        public String onGetToken(TokenContext tokenContext) {
                return authenticatedQueryToServerSide;
        }
};
// initialize JWT provider
AccessTokenProvider accessTokenProvider =
        new CallbackJwtProvider(getTokenCallback);

// App Key (you got this Key at Virgil Dashboard)
String appKeyBase64 = "MC4CAQAwBQYDK2VwBCIEINlK4BhgsijAbNmUqU6us0ZU9MGi+HxdYCA6TdZeHjR4";
byte[] appKeyData = ConvertionUtils.base64ToBytes(appKeyBase64);

// Crypto library imports a private key into a necessary format
VirgilCrypto crypto = new VirgilCrypto();
PrivateKey appKey = crypto.importPrivateKey(appKeyData);

// initialize accessTokenSigner that signs users JWTs
AccessTokenSigner accessTokenSigner = new VirgilAccessTokenSigner();

// use your App Credentials you got at Virgil Dashboard:
String appId = "be00e10e4e1f4bf58f9b4dc85d79c77a"; // App ID
String appKeyId = "70b447e321f3a0fd"; // App Key ID
TimeSpan ttl = TimeSpan.fromTime(1, TimeUnit.HOURS); // 1 hour (JWT's lifetime)

// setup JWT generator with necessary parameters:
JwtGenerator jwtGenerator = new JwtGenerator(appId, appKey, appKeyId, ttl, accessTokenSigner);

// generate JWT for a user
// remember that you must provide each user with his unique JWT
// each JWT contains unique user's identity (in this case - Alice)
// identity can be any value: name, email, some id etc.
String identity = "Alice";
Jwt aliceJwt = jwtGenerator.generateToken(identity);

// as result you get users JWT, it looks like this: "eyJraWQiOiI3MGI0NDdlMzIxZjNhMGZkIiwidHlwIjoiSldUIiwiYWxnIjoiVkVEUzUxMiIsImN0eSI6InZpcmdpbC1qd3Q7dj0xIn0.eyJleHAiOjE1MTg2OTg5MTcsImlzcyI6InZpcmdpbC1iZTAwZTEwZTRlMWY0YmY1OGY5YjRkYzg1ZDc5Yzc3YSIsInN1YiI6ImlkZW50aXR5LUFsaWNlIiwiaWF0IjoxNTE4NjEyNTE3fQ.MFEwDQYJYIZIAWUDBAIDBQAEQP4Yo3yjmt8WWJ5mqs3Yrqc_VzG6nBtrW2KIjP-kxiIJL_7Wv0pqty7PDbDoGhkX8CJa6UOdyn3rBWRvMK7p7Ak"
// you can provide users with JWT at registration or authorization steps
// Send a JWT to client-side
String jwtString = aliceJwt.stringRepresentation();

// initialize Crypto library
CardCrypto cardCrypto = new VirgilCardCrypto();

VerifierCredentials yourBackendVerifierCredentials =
        new VerifierCredentials("YOUR_BACKEND",
                ConvertionUtils.base64ToBytes(PUBLIC_KEY_STR));

Whitelist yourBackendWhiteList =
        new Whitelist(Arrays.asList(yourBackendVerifierCredentials));

CardVerifier cardVerifier = new VirgilCardVerifier(cardCrypto,
        Arrays.asList(yourBackendWhiteList));

// initialize cardManager and specify accessTokenProvider, cardVerifier
CardManager cardManager = new CardManager(cardCrypto, accessTokenProvider, cardVerifier);

import com.virgilsecurity.crypto.VirgilCrypto;

VirgilCrypto crypto = new VirgilCrypto();

// generate a key pair
VirgilKeyPair keyPair = crypto.generateKeyPair();

// save a private key into key storage
privateKeyStorage.store(keyPair.getPrivateKey(), "Alice", null);

// publish user's card on the Cards Service
try {
    Card card = cardManager.publishCard(keyPair.getPrivateKey(), keyPair.getPublicKey(), "Alice");
    // Card is created
} catch (Exception e) {
    // Error occured
}

import com.virgilsecurity.crypto.VirgilCrypto;

VirgilCrypto crypto = new VirgilCrypto();

// prepare a message
String messageToEncrypt = "Hello, Bob!";
byte[] dataToEncrypt = ConvertionUtils.toBytes(messageToEncrypt);

// prepare a user's private key
Tuple<PrivateKey, Map<String, String>> alicePrivateKeyEntry =
        privateKeyStorage.load("Alice");
VirgilPrivateKey alicePrivateKey =
        (VirgilPrivateKey) alicePrivateKeyEntry.getLeft();

// using cardManager search for user's cards on Cards Service
try {
    List<Card> cards = cardManager.searchCards("Bob");
    // Cards are obtained
    List<VirgilPublicKey> bobRelevantCardsPublicKeys = new ArrayList<>();
    for (Card card : cards) {
        if (!card.isOutdated()) {
            bobRelevantCardsPublicKeys.add(
                    (VirgilPublicKey) card.getPublicKey());
        }
    }
    // sign a message with a private key then encrypt on a public key
    byte[] encryptedData = crypto.signThenEncrypt(dataToEncrypt,
            alicePrivateKey, bobRelevantCardsPublicKeys);
} catch (CryptoException | VirgilServiceException e) {
    // Error occured
}

import com.virgilsecurity.crypto.VirgilCrypto;

VirgilCrypto crypto = new VirgilCrypto();

// prepare a user's private key
Tuple<PrivateKey, Map<String, String>> bobPrivateKeyEntry =
        privateKeyStorage.load("Bob");
VirgilPrivateKey bobPrivateKey =
        (VirgilPrivateKey) bobPrivateKeyEntry.getLeft();

try {
    // using cardManager search for user's cards on Cards Service
    List<Card> cards = cardManager.searchCards("Alice");
    // Cards are obtained
    List<VirgilPublicKey> aliceRelevantCardsPublicKeys = new ArrayList<>();
    for (Card card : cards) {
        if (!card.isOutdated()) {
            aliceRelevantCardsPublicKeys.add(
                    (VirgilPublicKey) card.getPublicKey());
        }
    }

    // decrypt with a private key and verify using a public key
    byte[] decryptedData = crypto.decryptThenVerify(encryptedData,
            bobPrivateKey, aliceRelevantCardsPublicKeys);
} catch (CryptoException | VirgilServiceException e) {
    // Error occured
}

// using cardManager get a user's card from the Cards Service
try {
    Card card = cardManager.getCard("f4bf9f7fcbedaba0392f108c59d8f4a38b3838efb64877380171b54475c2ade8");
    // Card is obtained
} catch (CryptoException | VirgilServiceException e) {
    // Error occured
}

try {
    List<Card> cards = cardManager.searchCards("Bob");
    // Cards are obtained
} catch (CryptoException | VirgilServiceException e) {
    // Error occured
}