add persistency to pairings

app/build.gradle

@@ -9,7 +9,7 @@ android {
     buildToolsVersion "29.0.2"
     defaultConfig {
         applicationId "im.status.keycard.connect"
-        minSdkVersion 21
+        minSdkVersion 23
         targetSdkVersion 29
         versionCode 1
         versionName "1.0"
@@ -45,6 +45,7 @@ dependencies {
     implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
     implementation 'androidx.navigation:navigation-fragment-ktx:2.1.0'
     implementation 'androidx.navigation:navigation-ui-ktx:2.1.0'
+    implementation 'androidx.security:security-crypto:1.0.0-alpha02'
     implementation 'org.bouncycastle:bcprov-jdk15on:1.64'
     implementation 'com.github.status-im.status-keycard-java:android:3.0.1'
     implementation "com.github.walletconnect:kotlin-walletconnect-lib:0.9.3"

app/src/main/java/im/status/keycard/connect/InitActivity.kt

@@ -8,6 +8,7 @@ import android.util.Base64
 import android.view.View
 import im.status.keycard.globalplatform.Crypto
 import android.util.Base64.NO_PADDING
+import android.util.Base64.NO_WRAP
 import android.widget.TextView
 
 
@@ -49,6 +50,6 @@ class InitActivity : AppCompatActivity() {
     }
 
     fun randomToken(length: Int): String {
-        return Base64.encodeToString(Crypto.randomBytes(length), NO_PADDING)
+        return Base64.encodeToString(Crypto.randomBytes(length), NO_PADDING or NO_WRAP)
     }
 }

app/src/main/java/im/status/keycard/connect/MainActivity.kt

@@ -11,6 +11,7 @@ import androidx.navigation.ui.setupWithNavController
 import im.status.keycard.android.NFCCardManager
 import android.content.Intent
 import im.status.keycard.connect.card.*
+import im.status.keycard.connect.data.PairingManager
 
 class MainActivity : AppCompatActivity() {
     private lateinit var cardManager: NFCCardManager
@@ -26,6 +27,8 @@ class MainActivity : AppCompatActivity() {
 
         val appBarConfiguration = AppBarConfiguration(setOf(R.id.navigation_home, R.id.navigation_dashboard, R.id.navigation_notifications))
 
+        PairingManager.init(this)
+
         nfcAdapter = NfcAdapter.getDefaultAdapter(this)
         executor = CardScriptExecutor(this)
         executor.setScript(listOf(SelectCommand(), InitCommand(), OpenSecureChannelCommand(), VerifyPINCommand()))

app/src/main/java/im/status/keycard/connect/card/OpenSecureChannelCommand.kt

@@ -29,6 +29,8 @@ class OpenSecureChannelCommand : CardCommand {
                 PairingManager.putPairing(cmdSet.applicationInfo.instanceUID, cmdSet.pairing)
                 cmdSet.autoOpenSecureChannel()
                 return CommandResult.OK
+            } catch(e: IOException) {
+                e.printStackTrace()
             } finally {
                 pairingPassword = null
             }

app/src/main/java/im/status/keycard/connect/data/PairingManager.kt

@@ -1,21 +1,43 @@
 package im.status.keycard.connect.data
 
+import android.content.Context
+import android.content.SharedPreferences
+import android.util.Base64
+import android.util.Base64.NO_PADDING
+import android.util.Base64.NO_WRAP
 import im.status.keycard.applet.Pairing
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+
 
 object PairingManager {
-    //TODO: persistency
+    private lateinit var sharedPreferences: SharedPreferences
 
-    private val pairings: MutableMap<ByteArrayKey, Pairing> = HashMap()
+    private fun id(instanceUID: ByteArray) : String {
+        return Base64.encodeToString(instanceUID, NO_PADDING or NO_WRAP)
+    }
+
+    fun init(context: Context) {
+        val masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC)
+        sharedPreferences = EncryptedSharedPreferences.create("pairings", masterKeyAlias, context, EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV, EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM)
+    }
 
     fun getPairing(instanceUID: ByteArray): Pairing? {
-        return pairings[ByteArrayKey(instanceUID)]
+        val p = sharedPreferences.getString(id(instanceUID), null)
+        return if (p != null) Pairing(p) else null
     }
 
     fun putPairing(instanceUID: ByteArray, pairing: Pairing) {
-        pairings[ByteArrayKey(instanceUID)] = pairing
+        sharedPreferences.edit().apply {
+            putString(id(instanceUID), pairing.toBase64())
+            apply()
+        }
     }
 
     fun removePairing(instanceUID: ByteArray) {
-        pairings.remove(ByteArrayKey(instanceUID))
+        sharedPreferences.edit().apply {
+            remove(id(instanceUID))
+            apply()
+        }
     }
 }