more improvements for #24 and #40 - generate and store new random passphrase for key

- this happens on first time creation of the private keyring

Author: n8fr8

android-libproofmode/src/main/java/org/witness/proofmode/crypto/pgp/PgpUtils.java

@@ -297,6 +297,14 @@ public boolean verifyDetachedSignature (InputStream fileStream, InputStream sigS
         return DetachedSignatureProcessor.verifySignature(fileStream, sigStream, pubKey);
     }
 
+    public static boolean keyRingExists (Context context)
+    {
+        File fileSecKeyRing = new File(context.getFilesDir(),FILE_SECRET_KEY_RING);
+        File filePubKeyRing = new File(context.getFilesDir(),FILE_PUBLIC_KEY_RING);
+
+        return fileSecKeyRing.exists() && filePubKeyRing.exists();
+    }
+
     public synchronized void initCrypto (Context context, String password) throws IOException, PGPException {
         if (pgpSec == null) {
 

app/src/main/java/org/witness/proofmode/ProofModeApp.kt

@@ -24,6 +24,7 @@ import org.witness.proofmode.notaries.OpenTimestampsNotarizationProvider
 import timber.log.Timber
 import java.io.IOException
 import java.util.concurrent.Executors
+import kotlin.random.Random
 
 /**
  * Created by n8fr8 on 10/10/16.
@@ -41,8 +42,24 @@ class ProofModeApp : MultiDexApplication() {
             var pubKey: String? = null
             try {
                 val prefs = PreferenceManager.getDefaultSharedPreferences(this)
-                pubKey = PgpUtils.getInstance(applicationContext,prefs.getString(PREFS_KEY_PASSPHRASE,
-                    PREFS_KEY_PASSPHRASE_DEFAULT)).publicKeyFingerprint
+
+                if (PgpUtils.keyRingExists(this)) {
+                    pubKey = PgpUtils.getInstance(
+                        applicationContext, prefs.getString(
+                            PREFS_KEY_PASSPHRASE,
+                            PREFS_KEY_PASSPHRASE_DEFAULT
+                        )
+                    ).publicKeyFingerprint
+                }
+                else
+                {
+                    var newPassPhrase = getRandPassword(12)
+                    prefs.edit().putString(PREFS_KEY_PASSPHRASE,newPassPhrase).commit()
+                    pubKey = PgpUtils.getInstance(
+                        applicationContext, newPassPhrase
+                    ).publicKeyFingerprint
+
+                }
 
             } catch (e: PGPException) {
                 Timber.e(e, "error getting public key")
@@ -54,6 +71,22 @@ class ProofModeApp : MultiDexApplication() {
         }
     }
 
+    fun getRandPassword(n: Int): String
+    {
+        val characterSet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+        val random = Random(System.nanoTime())
+        val password = StringBuilder()
+
+        for (i in 0 until n)
+        {
+            val rIndex = random.nextInt(characterSet.length)
+            password.append(characterSet[rIndex])
+        }
+
+        return password.toString()
+    }
+
     private fun showToastMessage(message: String) {
         val handler = Handler(Looper.getMainLooper())
         handler.post {