add certificate pinning support for Android

README.md

@@ -4,9 +4,6 @@
 >
 > This repository contains a proof-of-concept React Native plugin and an example mobile application intended solely for technical evaluation.
 >
-> Only the iOS integration has been verified to work at this time.
-> The Android bridge and Android example setup exist but have not been tested and are expected to require additional adjustments before they can be considered functional.
->
 > This repository is **experimental**, **not formally approved**, **not officially released**, **not published as an npm package**, and **not endorsed by WebID for
 > production use**.
 >
@@ -38,12 +35,14 @@ cp .env.example .env
 URL=https://test.webid-solutions.de
 USERNAME=your_username
 API_KEY=your_api_key
-CERT_BASE64=On ANdroid it need to be SHA-PINS
-# SHA_PINS=sha256/AAAA...,sha256/BBBB...
+CERT_BASE64=
 ```
 
 Edit the .env file and add your username and API key.
 
+ℹ️ The provided CERT_BASE64 value is preconfigured for the test system and is valid until 2026-02-21.
+In most cases, this value does not need to be modified if you intend to test against the test environment.
+
 ### Install Dependencies
 
 From the repository root:

android/src/main/java/com/webidmetaplugin/WebIdMetaPluginModule.kt

@@ -24,6 +24,11 @@ import java.net.URI
 import com.facebook.react.bridge.UiThreadUtil
 import android.util.Log
 import com.google.gson.Gson
+import java.io.ByteArrayInputStream
+import java.security.MessageDigest
+import java.security.cert.CertificateFactory
+import java.security.cert.X509Certificate
+import android.util.Base64
 
 private const val TAG = "WebIdMetaPlugin"
 
@@ -53,6 +58,53 @@ class WebIdMetaPluginModule(
     listenerCount = (listenerCount - count).coerceAtLeast(0)
   }
 
+  private fun toPinningShaKey(inputRaw: String): String {
+    val input = inputRaw.trim()
+
+    if (input.startsWith("sha256/") || input.startsWith("sha1/")) return input
+
+    val justValue = input.substringAfter("=", input).trim()
+
+    val base64Cert = justValue
+      .replace("-----BEGIN CERTIFICATE-----", "")
+      .replace("-----END CERTIFICATE-----", "")
+      .replace("\\s+".toRegex(), "")
+
+    require(base64Cert.isNotEmpty()) { "Certificate input is empty after normalization" }
+
+    val certBytes = try {
+      Base64.decode(base64Cert, Base64.DEFAULT)
+    } catch (e: IllegalArgumentException) {
+      throw IllegalArgumentException("Certificate is not valid Base64 (DER/PEM).", e)
+    }
+
+    val x509 = try {
+      val cf = CertificateFactory.getInstance("X.509")
+      cf.generateCertificate(ByteArrayInputStream(certBytes)) as X509Certificate
+    } catch (e: Exception) {
+      throw IllegalArgumentException("Could not parse X.509 certificate bytes.", e)
+    }
+
+    val spkiBytes = x509.publicKey.encoded
+    val digest = MessageDigest.getInstance("SHA-256").digest(spkiBytes)
+    val pinB64 = Base64.encodeToString(digest, Base64.NO_WRAP)
+
+    return "sha256/$pinB64"
+  }
+
+  private fun toPinningShaKeys(inputs: List<String>): Array<String> =
+    inputs
+      .map { it.trim() }
+      .filter { it.isNotEmpty() }
+      .map { toPinningShaKey(it) }
+      .toTypedArray()
+
+  private fun shortPreview(s: String): String {
+    val t = s.trim()
+    if (t.length <= 12) return t
+    return "${t.take(6)}...${t.takeLast(6)}"
+  }
+
   @ReactMethod
   fun createMetaPlugin(
     uri: String,
@@ -69,10 +121,13 @@ class WebIdMetaPluginModule(
     val shaPinsList = shaPins.toArrayList().map { it.toString() }
     val pluginsList = plugins.toArrayList().map { it.toString() }
 
+    val pinningShaKeys = toPinningShaKeys(shaPinsList)
+    Log.i(TAG, "createMetaPlugin pins(mapped) len=${pinningShaKeys.size} values=${pinningShaKeys.map { shortPreview(it) }}")
+
     try {
       val environment = WebIdSdkEnvironment(
         URI.create(cleanUri),
-        *shaPinsList.toTypedArray()
+        *pinningShaKeys
       )
 
       val selectedPlugins = ArrayList<IProductPluginWebId>()