Parse vci request and prepare for credential endpoint call.

Note the credential endpoint part is neither tested nor invoked for now.

app/build.gradle.kts

@@ -1,6 +1,7 @@
 plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.kotlin.android)
+    alias(libs.plugins.kotlin.serialization)
     alias(libs.plugins.kotlin.compose)
     alias(libs.plugins.devtool.ksp)
 }
@@ -40,6 +41,8 @@ android {
 }
 
 dependencies {
+    implementation(libs.ktor.client.core)
+    implementation(libs.ktor.client.cio)
     implementation(libs.androidx.lifecycle.viewmodel.compose)
     implementation(libs.androidx.registry.digitalcredentials.mdoc)
     implementation(libs.androidx.registry.digitalcredentials.preview)
@@ -61,6 +64,7 @@ dependencies {
     implementation(libs.androidx.room.runtime)
     ksp(libs.androidx.room.compiler)
     testImplementation(libs.junit)
+    implementation(libs.kotlinx.serialization.json)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.espresso.core)
     androidTestImplementation(platform(libs.androidx.compose.bom))

app/src/main/assets/openid4vci_request.json

@@ -5,6 +5,7 @@
       ],
     "issuer_metadata": {
         "credential_issuer": "https://credential-issuer.example.com",
+        "credential_endpoint": "https://credential-issuer.example.com",
         "credential_configurations_supported": {
             "com.emvco.payment_card": {
                 "format": "mso_mdoc",

app/src/main/java/com/credman/cmwallet/CreateCredentialActivity.kt

@@ -11,11 +11,14 @@ import androidx.activity.ComponentActivity
 import androidx.credentials.CreateCustomCredentialResponse
 import androidx.credentials.DigitalCredential
 import androidx.credentials.ExperimentalDigitalCredentialApi
+import androidx.credentials.exceptions.CreateCredentialUnknownException
 import androidx.credentials.provider.CallingAppInfo
 import androidx.credentials.provider.PendingIntentHandler
 import androidx.credentials.provider.ProviderCreateCredentialRequest
-import androidx.credentials.registry.provider.selectedEntryId
 import com.credman.cmwallet.CmWalletApplication.Companion.TAG
+import com.credman.cmwallet.openid4vci.DATA
+import com.credman.cmwallet.openid4vci.OpenId4VCI
+import com.credman.cmwallet.openid4vci.PROTOCOL
 import org.json.JSONObject
 
 @OptIn(ExperimentalDigitalCredentialApi::class)
@@ -36,17 +39,42 @@ class CreateCredentialActivity : ComponentActivity() {
         ) ?: ""
         Log.i(TAG, "[CreateCredentialActivity] origin $origin")
 
-        val testResponse = CreateCustomCredentialResponse(
-            type = DigitalCredential.TYPE_DIGITAL_CREDENTIAL,
-            data = Bundle().apply {
-                putString("androidx.credentials.BUNDLE_KEY_RESPONSE_JSON", "test response")
-            },
-        )
+        try {
+            // This will eventually be replaced by a structured Jetpack property,
+            // as opposed to having to parse a raw data from Bundle.
+            val requestJsonString: String = request.callingRequest.credentialData.getString(
+                "androidx.credentials.BUNDLE_KEY_REQUEST_JSON"
+            )!!
 
-        val resultData = Intent()
-        PendingIntentHandler.setCreateCredentialResponse(resultData, testResponse)
-        setResult(RESULT_OK, resultData)
-        finish()
+            val requestJson = JSONObject(requestJsonString)
+            require(requestJson.has(PROTOCOL)) { "request json missing required field $PROTOCOL" }
+            require(requestJson.has(DATA)) { "request json missing required field $DATA" }
+
+            Log.d(TAG, "Request json received: ${requestJson.getString(DATA)}")
+
+            val openId4VCI = OpenId4VCI(requestJson.getString(DATA))
+
+            val testResponse = CreateCustomCredentialResponse(
+                type = DigitalCredential.TYPE_DIGITAL_CREDENTIAL,
+                data = Bundle().apply {
+                    putString("androidx.credentials.BUNDLE_KEY_RESPONSE_JSON", "test response")
+                },
+            )
+
+            val resultData = Intent()
+            PendingIntentHandler.setCreateCredentialResponse(resultData, testResponse)
+            setResult(RESULT_OK, resultData)
+            finish()
+        } catch (e: Exception) {
+            Log.e(TAG, "exception", e)
+            val resultData = Intent()
+            PendingIntentHandler.setCreateCredentialException(
+                resultData,
+                CreateCredentialUnknownException(),
+            )
+            setResult(RESULT_OK, resultData)
+            finish()
+        }
     }
 
     /**

app/src/main/java/com/credman/cmwallet/openid4vci/CredentialEndpointDataModel.kt

@@ -0,0 +1,49 @@
+package com.credman.cmwallet.openid4vci
+
+import android.util.Log
+import com.credman.cmwallet.CmWalletApplication.Companion.TAG
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+
+internal val jsonFormat = Json { explicitNulls = false }
+
+fun String.toCredentialResponse(): CredentialResponse? {
+    return try {
+        jsonFormat.decodeFromString<CredentialResponse>(this)
+    } catch (e: Exception) {
+        Log.e(TAG, "credential response parsing exception", e)
+        null
+    }
+}
+
+@Serializable
+data class CredentialResponse(
+    val credentials: List<Credential>? = null,
+    val transaction_id: String? = null,
+    val notification_id: String? = null,
+)
+
+@Serializable
+data class Credential(
+    // Technically this could also be an object
+    val credential: String,
+)
+
+@Serializable
+data class CredentialRequest(
+    val credential_configuration_id: String,
+    val proof: Proof? = null,
+) {
+    fun toJson(): String {
+        return jsonFormat.encodeToString(this)
+    }
+}
+
+@Serializable
+class Proof(
+    val proof_type: String,
+    val jwt: String?,
+)
+
+internal const val JWT = "jwt"

app/src/main/java/com/credman/cmwallet/openid4vci/RequestDataModel.kt → app/src/main/java/com/credman/cmwallet/openid4vci/CredentialOfferDataModel.kt

@@ -187,4 +187,7 @@ internal const val BACKGROUND_IMAGE = "background_image"
 internal const val BACKGROUND_COLOR = "background_color"
 internal const val TEXT_COLOR = "text_color"
 internal const val VALUE_TYPE = "value_type"
-internal const val ALT_TEXT = "alt_text"
+internal const val ALT_TEXT = "alt_text"
+internal const val CREDENTIAL_ENDPOINT = "credential_endpoint"
+const val PROTOCOL = "protocol"
+const val DATA = "data"

app/src/main/java/com/credman/cmwallet/openid4vci/OpenId4VCI.kt

@@ -1,12 +1,26 @@
 package com.credman.cmwallet.openid4vci
 
+import android.util.Log
+import com.credman.cmwallet.CmWalletApplication.Companion.TAG
+import io.ktor.client.HttpClient
+import io.ktor.client.call.body
+import io.ktor.client.engine.cio.CIO
+import io.ktor.client.request.post
+import io.ktor.client.request.setBody
+import io.ktor.http.ContentType
+import io.ktor.http.HttpHeaders
+import io.ktor.http.contentType
+import io.ktor.http.headers
 import org.json.JSONObject
 
 class OpenId4VCI(val request: String) {
     val requestJson: JSONObject = JSONObject(request)
 
     val credentialIssuer: String
     val credentialConfigurationIds: List<String>
+
+    // Credential Issuer Metadata Parameters
+    val credentialEndpoint: String
     val credentialConfigurationsSupportedMap: Map<String, CredConfigsSupportedItem>
 
     init {
@@ -23,8 +37,11 @@ class OpenId4VCI(val request: String) {
             }
             ids
         }
+        require(credentialConfigurationIds.isNotEmpty()) { "Credential configuration id list shouldn't be empty" }
 
         val issuerMetadataJson = requestJson.getJSONObject(ISSUER_METADATA)
+        require(issuerMetadataJson.has(CREDENTIAL_ENDPOINT)) { "Issuance request must contain $CREDENTIAL_ENDPOINT" }
+        credentialEndpoint = issuerMetadataJson.getString(CREDENTIAL_ENDPOINT)
         require(issuerMetadataJson.has(CREDENTIAL_CONFIGURATION_SUPPORTED)) { "Issuance request must contain $CREDENTIAL_CONFIGURATION_SUPPORTED" }
         val credConfigSupportedJson = issuerMetadataJson.getJSONObject(CREDENTIAL_CONFIGURATION_SUPPORTED)
         val itr = credConfigSupportedJson.keys()
@@ -36,4 +53,44 @@ class OpenId4VCI(val request: String) {
         }
         credentialConfigurationsSupportedMap = tmpMap
     }
+
+    suspend fun requestCredential() {
+        val client = HttpClient(CIO)
+        val httpResponse = client.post(credentialEndpoint) {
+            headers {
+                append(HttpHeaders.Authorization, getAuthToken())
+            }
+            contentType(ContentType.Application.Json)
+            setBody(
+                CredentialRequest(
+                    credentialConfigurationIds.first(),
+                    proof = Proof(
+                        JWT,
+                        jwt = generateDeviceKeyJwt()
+                    )
+                ).toJson()
+            )
+        }
+
+        if (httpResponse.status.value == 202) {
+            Log.d(TAG, "Successful credential endpoint response." +
+                    "Content type: ${httpResponse.headers[HttpHeaders.ContentType]}, " +
+                    "Content body: ${httpResponse.body<String>()}")
+            val credResponse = httpResponse.body<String>().toCredentialResponse()
+            // TODO: remove !!
+            val credential = credResponse!!.credentials!!.first().credential
+            TODO()
+        } else {
+            Log.e(TAG, "Error credential endpoint code: ${httpResponse.status.value}")
+            TODO()
+        }
+    }
+
+    private fun generateDeviceKeyJwt(): String {
+        return "TODO"
+    }
+
+    private fun getAuthToken(): String {
+        return "TODO"
+    }
 }

build.gradle.kts

@@ -2,6 +2,7 @@
 plugins {
     alias(libs.plugins.android.application) apply false
     alias(libs.plugins.kotlin.android) apply false
+    alias(libs.plugins.kotlin.serialization) apply false
     alias(libs.plugins.kotlin.compose) apply false
     alias(libs.plugins.devtool.ksp) apply false
 }

gradle/libs.versions.toml

@@ -1,11 +1,13 @@
 [versions]
 agp = "8.7.1"
 kotlin = "2.0.21"
+kotlinxSerializationJson = "1.7.3"
 ksp = "2.0.21-1.0.27"
 coreKtx = "1.10.1"
 junit = "4.13.2"
 junitVersion = "1.1.5"
 espressoCore = "3.5.1"
+ktorClient = "3.0.1"
 lifecycleRuntimeKtx = "2.6.1"
 activityCompose = "1.8.0"
 composeBom = "2024.04.01"
@@ -36,6 +38,9 @@ androidx-ui-tooling-preview = { group = "androidx.compose.ui", name = "ui-toolin
 androidx-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-manifest" }
 androidx-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
 androidx-material3 = { group = "androidx.compose.material3", name = "material3" }
+kotlinx-serialization-json = { module = "org.jetbrains.kotlinx:kotlinx-serialization-json", version.ref = "kotlinxSerializationJson" }
+ktor-client-cio = { module = "io.ktor:ktor-client-cio", version.ref = "ktorClient" }
+ktor-client-core = { module = "io.ktor:ktor-client-core", version.ref = "ktorClient" }
 lifecycle-runtime-ktx = { module = "androidx.lifecycle:lifecycle-runtime-ktx" }
 androidx-lifecycle-runtime-compose-android = { group = "androidx.lifecycle", name = "lifecycle-runtime-compose-android", version.ref = "lifecycleRuntimeComposeAndroid" }
 androidx-room-ktx = { group = "androidx.room", name = "room-ktx", version.ref = "roomRuntime" }
@@ -44,5 +49,6 @@ play-services-identity-credentials = {module = "com.google.android.gms:play-serv
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }
 kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
+kotlin-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlin" }
 kotlin-compose = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
 devtool-ksp = { id = "com.google.devtools.ksp", version.ref = "ksp"}