API Guidelines

App2App SDK Integration Specs

Description & Use

Rp SDK is an App2App SDK for Samsung Wallet driver's license service online scenarios.
This SDK provides an implementation for direct communication between the Samsung Wallet and Partner applications.

Build the settings

RpSdk requires additional dependencies with:

dependencies {
    ...
    implementation("rp-sdk-1.0-release.aar")
    implementation("androidx.core:core-ktx:1.3.2")
    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
    implementation("androidx.lifecycle:lifecycle-livedata-core-ktx:2.7.0")
    implementation("io.reactivex.rxjava2:rxjava:2.2.21")
    implementation("io.reactivex.rxjava2:rxkotlin:2.4.0")
    implementation("io.reactivex.rxjava2:rxandroid:2.1.1")
    implementation("com.squareup.okhttp3:okhttp:4.11.0")
    implementation("com.google.code.gson:gson:2.10.1")
    implementation("org.bouncycastle:bcprov-jdk15to18:1.66")
    implementation("com.nimbusds:nimbus-jose-jwt:9.37.3")
    ...
}

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    ...
    <uses-permission android:name="android.permission.INTERNET" />
     <queries>
        <package android:name="com.samsung.android.spay" />
    </queries>
    ...
</manifest>

R8 / Proguard

The specific rules are already bundled into the AAR which can be interpreted by R8 automatically

SDK Method

App2App SDK supports one method.

  • request()

Signature & parameters of the request method.

fun request(targetPackageName: String, requestId: String, appLink: String, onResponseListener: OnResponseListener? = null)

Parameter name

 Description
targetPackageName

 The Pakcage name to connect to.
requestId

 A Random string to identify each request
appLink

 The appLink built by Samsung MCS server guide
onResponseListener

 A listener to receive each events or requests

[Sample code]

binding.button.setOnClickListener {
    rpClientApis.request("com.samsung.android.spay", UUID.randomUUID().toString(), appLink, object : RpClientApis.OnResponseListener {
        override fun onGetMdocRequestData(deviceEngagementBytes: ByteArray): ByteArray? {
            Log.i(TAG, "onGetMdocRequestData($deviceEngagementBytes)")
            /**
            * 1. prepare mDoc request data (ISO-18013-5)
            * 2. build sessionEstablishmentBytes (ISO-18013-5)
            * 3. Encrypt it with HKDF (ISO-18013-5, 9.1.1.5 Cryptographic operations)
            **/
            return "encryptedSessionEstablishmentBytes"
        }
         override fun onMdocResponse(encryptedResponse: ByteArray) {
            Log.i(TAG, "onMdocResponse($encryptedResponse)")
            /**
            * 1. Decrypt it with HKDF (ISO-18013-5, 9.1.1.5 Cryptographic operations)
            * 2. CBOR decode it
            **/
        }
         override fun onMdocResponseFailed(exception: Exception) {
            Log.i(TAG, "onMdocResponseFailed($exception)")
        }
    })
}

Error Code Explanation

The below exceptions might occur through the onMdocResponseFailed callback

Exceptions name

 Description
RpCommunicationException

 This error occurs when the data requested by the listener is incorrect.
RpConnectionFailedException

 This occurs when the App 2 App communication between apps is not working.
This usually occurs when the target Package Name is written incorrectly

Web2App API Integration Specs

The API specifications that need to be implemented by the RP partner are described below:

Called by Samsung to the RP partner

Send Key

Send the Wallet application key info and return the data field types requested to the client for authentication of the mDL

[Request]

Type

 Value

 Description
Method

 POST
URL

 {Partner server URL}/rp/v1.0/{cardId}/{RefId}/key
Headers

 Authorization
String(1024)

 (Required)
Credential token.
The token can have the prefix "Bearer" as an authorization type, e.g., Bearer <credentials>.
* Refer to Authorization Token for more details.
Path Parameters

 cardId
String(32)

 (Required)
Wallet card identifier issued from Partner portal when the partner manager signs up for partner services and registers the wallet card they want to service.
refId
String(32)

 (Required)
Unique content identifier defined by the content provider
Query Parameter

 N/A
Payload

 data
String(3000)

 (Required)
JWT data encrypted with the public key information and card type.
If decrypted this data is decoded, and it has the following format information.
{
“data”: “XXXXXXXXXXX”,
“card”: {
"type": "relyingparty",
"subType": "others",
"designType": "us-01"
}
}

[Example]

POST {Partner server URL}/rp/v1.0/{cardId}/{RefId}/key
Content-Type: application/json
{
“data”: “eyJjdHkiOiJBVVRIIiwidmVyIjoiMiIsInBhcnRuZXJJZCI6InRlc3QiLCJ1dGMiOjE3MTYyMDYzNjAxMTAsImFsZyI6IlJTMjU2In0.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.E07YYl7IoR3885VYKsS5_q1IcpX750uU2Ge5suJSedx3Dr_U0x4tSe9_0NxM46dyWnFUXrUAGfjDnjHIBc707Li9VI3XtyiHwnwEiFydgv1QB9oddkYyZuahXQmJHVUqNcdt6DF2CAqzF5QgMVqfMGSE_t7IPU8vQFXE34DO-sKzj8ftdusS2EcdANBqOKCHih3m39NouBPFhcX68PlPcW50diXlupxwEGniU2t3Co24YlIaKLGac669aCcXDQr34utVUqhTJt_FTXkahAlzoA34_Hj_s82FivIXh1ITD74UOjZSe7IBWya_kVysoZavnmzTz2tH9CbwyCvx8wA”
}

[Response]

Type

 Value

 Description
HTTP Status code

 200 OK
Payload

 data
String(3000)

 (Required)
JWT data encrypted with the data field types requested to the client
for authentication of the mDL.

[Result]

HTTP status code

 Description
200 OK

 Success
400 Bad Request

 Requests cannot or will not be processed due to something that is perceived to be a client error.
401 Unauthorized

 Authorization token is invalid or expired.
500 Internal Server Error

 The server encountered an unexpected condition that prevented it from fulfilling the request.
503 Service Unavailable

 The server is not ready to handle the request.

Send authentication data

The data is encrypted according to the requested data and then transmitted along with the data card information.

[Request]

Type

 Value

 Description
Method

 POST
URL

 {Partner server URL}/rp/v1.0/{cardId}/{RefId}/auth
Headers

 Authorization
String(1024)

 (Required)
Credential token.
The token can have the prefix "Bearer" as an authorization type, e.g., Bearer <credentials>.
* Refer to Authorization Token for more details.
PathParameters

 cardId
String(32)

 (Required)
Wallet card identifier issued from Partner portal when the partner manager signs up for partner services and registers the wallet card they want to service.
refId
String(32)

 (Required)
Unique content identifier defined by the content provider
QueryParameter

 N/A
Payload

 data
String(3000)

 (Required)
JWT data encrypted with the public key information and card type.
If decrypted this data is decoded, it has the following format information.
{
“data”: “XXXXXXXXXXX”,
“card”: {
"type": "idcard",
"subType": "drivers",
"designType": "us-01"
}
}

[Example]

POST {Partner server URL}/rp/v1.0/{cardId}/{RefId}/auth
Content-Type: application/json
{
“data”: “eyJjdHkiOiJBVVRIIiwidmVyIjoiMiIsInBhcnRuZXJJZCI6InRlc3QiLCJ1dGMiOjE3MTYyMDYzNjAxMTAsImFsZyI6IlJTMjU2In0.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.E07YYl7IoR3885VYKsS5_q1IcpX750uU2Ge5suJSedx3Dr_U0x4tSe9_0NxM46dyWnFUXrUAGfjDnjHIBc707Li9VI3XtyiHwnwEiFydgv1QB9oddkYyZuahXQmJHVUqNcdt6DF2CAqzF5QgMVqfMGSE_t7IPU8vQFXE34DO-sKzj8ftdusS2EcdANBqOKCHih3m39NouBPFhcX68PlPcW50diXlupxwEGniU2t3Co24YlIaKLGac669aCcXDQr34utVUqhTJt_FTXkahAlzoA34_Hj_s82FivIXh1ITD74UOjZSe7IBWya_kVysoZavnmzTz2tH9CbwyCvx8wA”
}

[Response]

Type

 Value

 Description
HTTP Status code

 200 OK
400 Bad Request

[Result]

HTTP status code

 Description
200 OK

 Success
400 Bad Request

 Requests cannot or will not be processed due to something
that is perceived to be a client error.
401 Unauthorized

 Authorization token is invalid or expired.
500 Internal Server Error

 The server encountered an unexpected condition that prevented it from fulfilling the request.
503 Service Unavailable

 The server is not ready to handle the request.

Code explanation based on the sample code

JWT (JWS + JWE) decryption between the Wallet Backed Server and partner server

1. Verify by generateing a JWS using the body data

// Generate JWS by the body data
private static SignedJWT parseJWT(final String data)  {
    try {
    return SignedJWT.parse(data);
} catch (ParseException e) {
    log.error("parserJWT error class : {}, error message : {}", e.getClass(), e.getMessage());
    throw new CustomException(HttpStatus.INTERNAL_SERVER_ERROR, "parserJWT error");
    }
}

// Verify JWS using Samsung Public key
public RequestBody getRequestBody(final KeyRing keyRing) {
    final SignedJWT signedJWT = JWTUtils.verify(keyRing.getTargetPublicKey(), encryptedData, 60 * 10000); // Verify and generate JWS
    try {
    final String strBody = JWTUtils.getDecryptedPayloadFrom(keyRing.getSourcePrivateKey(), JWEObject.parse(signedJWT.getPayload().toString())); // Decryption JWE by the JWS
    return objectMapper.readValue(strBody, RequestBody.class); // Convert to data format requested by client
    } catch (ParseException | JsonProcessingException e) {
        log.error("getRequestBody : {}", e.getMessage());
        throw new CustomException(HttpStatus.INTERNAL_SERVER_ERROR, "data body parse error");
    }
}

2. Decrypt the JWE using the JWS

JWEObject.parse(signedJWT.getPayload().toString())

public static String getDecryptedPayloadFrom(final Key privateKey, final JWEObject data) {
    try {
        data.decrypt(new RSADecrypter((PrivateKey) privateKey));  // Decryption JWE using Partner Private Key
        return data.getPayload().toString();
    } catch (JOSEException e) {
        log.error("JOSEException message : {}", e.getMessage());
        throw new CustomException(HttpStatus.INTERNAL_SERVER_ERROR, "getDecryptedPayloadFrom error");
    }
}

3. Convert to the format send by the client

public RequestBody getRequestBody(final KeyRing keyRing) {
    final SignedJWT signedJWT = JWTUtils.verify(keyRing.getTargetPublicKey(), encryptedData, 60 * 10000); // Verify and generate JWS
    try {
        final String strBody = JWTUtils.getDecryptedPayloadFrom(keyRing.getSourcePrivateKey(), JWEObject.parse(signedJWT.getPayload().toString())); // Decryption JWE by the JWS
        return objectMapper.readValue(strBody, RequestBody.class); // Convert to data format requested by client
    } catch (ParseException | JsonProcessingException e) {
        log.error("getRequestBody : {}", e.getMessage());
        throw new CustomException(HttpStatus.INTERNAL_SERVER_ERROR, "data body parse error");
    }
}

Generate MdocEstablishment

1. Generate RSA Key per refId

public class TransactionContext {
    private final KeyPair keyPair;   // RSA Key
    private final byte[] clientEngagement; // Body data received through key API, base64URL decoded value

    @EqualsAndHashCode.Exclude
    private int encryptMessageCounter = 0;  // Count value when encrypted
    @EqualsAndHashCode.Exclude
    private int decryptMessageCounter = 0; // Count value when decrypted
}

private Cache<String, TransactionContext> contextCache; // RSA key management per refid with memory cache

// Generate and store RSA Key per refId only once upon first request
public TransactionContext setTransactionContext(final String key, final String base64EncodedClientEngagement) {
    log.info("base64EncodedClientPublicKey : {}", base64EncodedClientEngagement);
    this.contextCache.put(key, new TransactionContext(KeyUtils.generateKeyPair() , Base64Utils.decode(base64EncodedClientEngagement.getBytes())));
    return this.getTransactionContextBy(key);
    }

// Part of retrieving RAS Key based on refId
public TransactionContext getTransactionContextBy(final String key) {
    return Optional.ofNullable(this.contextCache.getIfPresent(key)).orElseThrow(() -> {
    log.info("{} is empty", key);
    return new CustomException(HttpStatus.BAD_REQUEST, "No key matching the refId");
    });
}

2. Create request field values

@Override
public Mono<List<String>> createRequest(final PartnerInputDTO inputDTO) {
    final String mockData = "{ \"docType\": \"org.iso.18013.5.1.mDL\", \"nameSpaces\": { \"org.iso.18013.5.1\": { \"sex\": false, \"portrait\": false, \"given_name\": false, \"issue_date\": false, \"expiry_date\": false, \"family_name\": false, \"document_number\": false, \"issuing_authority\": false }, \"org.iso.18013.5.1.aamva\": { \"DHS_compliance\": false, \"EDL_credential\": false } } }";
    return Mono.just(Collections.singletonList(mockData));
}

3. Generate Establishment

@AllArgsConstructor
public class Establishment {
    private final TransactionContext context; // Info of client public key , partner private key, public key
    private final List<String> strReqs; // Data field information required for authentication to the client
    private final KeyRing keyRing; // RSA Key information for JWT(JWS + JWE) encryption and decryption between Wallet Backed Server and partner server.
 }

protected CBORObject generate() {
    final CBORObject sessionEstablishment = CBORObject.NewMap();
    sessionEstablishment.set(E_READER_KEY, CBORObject.FromObjectAndTag(KeyUtils.getEReaderKey(context), TAG_SIZE));  // Generate oneKey by public key in transactionContext
    sessionEstablishment.set(DATA, CBORObject.FromObject(CipherUtils.encrypt(context, generateRequestFormat(getRequestCBORObjectsFrom(strReqs))))); // Add request data field information for authentication.
    return sessionEstablishment;
}

Generate the response value JWT(JWS + JWE)

1. Generate establishment with JWE

public static String encryptedStringJWE(final Key publicKey, final String data) {  // Please enter Samsung Public Key and establishment data
    final JWEObject jwe = new JWEObject(
    new JWEHeader.Builder(JWEAlgorithm.RSA_OAEP_256, EncryptionMethod.A128GCM).build(), new Payload(data));
    try {
        jwe.encrypt(new RSAEncrypter((RSAPublicKey) publicKey));
        return jwe.serialize();
    } catch (JOSEException e) {
        log.error("encryptedStringJWE Exception message : {}", e.getMessage());
        throw new CustomException(HttpStatus.INTERNAL_SERVER_ERROR, "encryptedStringJWE error");
    }
}

2. Generate JWS by JWE

public static String generateSignedStringJWS(final Key privateKey, final Key publicKey, final String payload) { // Enter your partner’s public key, private key, and JWE data.
  try {
    final JWSObject jwsObj = new JWSObject(getDefaultJWSHeader(), new Payload(payload));
    JWSSigner signer = new RSASSASigner(new RSAKey.Builder((RSAPublicKey) publicKey).privateKey((RSAPrivateKey) privateKey).build());
    jwsObj.sign(signer);
    return jwsObj.serialize();
  } catch (JOSEException e) {
    log.error("encryptedStringJWS Exception message : {}", e.getMessage());
    throw new CustomException(HttpStatus.INTERNAL_SERVER_ERROR, "generateSignedStringJWS error");
  }
}

3. Generate JWT(JWS + JWE)

public PartnerOutputDTO toPartnerOutputDTO() {
    final CBORObject generate = this.generate();
    final String establishment = Base64.getUrlEncoder().encodeToString(generate.EncodeToBytes());
    final String strJWE = JWTUtils.encryptedStringJWE(keyRing.getTargetPublicKey(), establishment);
    final JWSHeader jwsHeader = JWTUtils.getDefaultJWSHeader(keyRing.getVersion(), keyRing.getCertificateId(), "partnerId");
    return new PartnerOutputDTO(JWTUtils.generateSignedStringJWS(jwsHeader, keyRing.getSourcePrivateKey(), keyRing.getSourcePublicKey(),strJWE));
}

Authentication processing for values in data fields requested for authentication

1. Retrieve transactionContext value stored in cache using refId value

@Override
public Mono<TransactionContext> getContext(final PartnerInputDTO inputDTO) {
   return Mono.just(this.transactionContextManager.getTransactionContextBy(inputDTO.getRefId()));
}

2. Processes the decryption process of the request body data like JWT (JWS + JWE) decryption between Wallet Backed Server and partner server.

3. Generate MdocResponse

public class MdocResponse {
    private final TransactionContext context; // Managed tranactionContext by refId
    private final byte[] data; // Base64URL decoded data after decrypting JWT (JWS + JWE) data.
    
    public MdocResponse(final TransactionContext context, final String inputDTO) {
        this.context = context;
        this.data = Base64Utils.decode(inputDTO.getBytes(StandardCharsets.UTF_8));
    }
}

4. Get the field values requested for authentication from the data in mDocResponse.

public String getData() {
    // SessionData = {
    //     ? "data" : bstr ; Encrypted mdoc response or mdoc request
    //     ? "status" : uint ; Status code
    // }
    final CBORObject response = CBORObject.DecodeFromBytes(data);
    checkType(response, CBORType.Map);
    final CBORObject data = response.get(DATA);
    checkType(data, CBORType.ByteString);
    
    return CBORObject.DecodeFromBytes(isEncryptedMode ? CipherUtils.decrypt(this.context, data.GetByteString()) : data.GetByteString()).ToJSONString();
}

5. Create a Session value using the transactionContext value managed by refId and then decrypt it.

private static byte[] processCipher(final CipherMode cipherMode, final TransactionContext context, final byte[] bytes) { //  CipherMode : encrypt or decrypt, bytes : Data passed by the client
    try {
        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
        final int counter = CipherMode.ENCRYPT == cipherMode ? context.getEncryptMessageCounter() : context.getDecryptMessageCounter();
        GCMParameterSpec parameterSpec = new GCMParameterSpec(128, getSessionKeyIv(cipherMode.identifier, counter));
        cipher.init(cipherMode.cipherMode , getSecretKeySpec(context, cipherMode.info), parameterSpec);
        return cipher.doFinal(bytes);
    } catch (InvalidAlgorithmParameterException | NoSuchPaddingException | IllegalBlockSizeException |
        NoSuchAlgorithmException | BadPaddingException | InvalidKeyException e) {
        log.error("error type : {}, message :{}", e.getClass(), e.getMessage());
        throw new CustomException(HttpStatus.INTERNAL_SERVER_ERROR, "processCipher error");
    }
}

6. Examining data received from the client.

@Override
public Mono<Void> authentication(final String response) {
    log.info("response info : {}", response);
    return Mono.empty();
}