Rewrite pwgen package in Kotlin (#463)

* Rename classes to not be ugly as all hell

Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>

* PgpActivity: Cleanup

Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>

* Rewrite pwgen package in Kotlin

Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>

* PRNGFixes: Remove constant conditions

Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>

13 files changed, 773 insertions, 807 deletions

diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgenDialogFragment.java b/app/src/main/java/com/zeapo/pwdstore/PasswordGeneratorDialogFragment.java
index d7d1ae45..1a51f6f2 100644
--- a/app/src/main/java/com/zeapo/pwdstore/pwgenDialogFragment.java
+++ b/app/src/main/java/com/zeapo/pwdstore/PasswordGeneratorDialogFragment.java
@@ -16,7 +16,7 @@ import android.widget.EditText;
 import android.widget.TextView;
 import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.DialogFragment;
-import com.zeapo.pwdstore.pwgen.pwgen;
+import com.zeapo.pwdstore.pwgen.PasswordGenerator;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
@@ -25,9 +25,9 @@ import java.util.ArrayList;
 /**
  * A placeholder fragment containing a simple view.
  */
-public class pwgenDialogFragment extends DialogFragment {
+public class PasswordGeneratorDialogFragment extends DialogFragment {
 
-    public pwgenDialogFragment() {
+    public PasswordGeneratorDialogFragment() {
     }
 
 
@@ -44,7 +44,7 @@ public class pwgenDialogFragment extends DialogFragment {
         builder.setView(view);
 
         SharedPreferences prefs
-                = getActivity().getApplicationContext().getSharedPreferences("pwgen", Context.MODE_PRIVATE);
+                = getActivity().getApplicationContext().getSharedPreferences("PasswordGenerator", Context.MODE_PRIVATE);
 
         CheckBox checkBox = view.findViewById(R.id.numerals);
         checkBox.setChecked(!prefs.getBoolean("0", false));
@@ -90,7 +90,7 @@ public class pwgenDialogFragment extends DialogFragment {
             public void onShow(DialogInterface dialog) {
                 setPreferences();
                 TextView textView = view.findViewById(R.id.passwordText);
-                textView.setText(pwgen.generate(getActivity().getApplicationContext()).get(0));
+                textView.setText(PasswordGenerator.INSTANCE.generate(getActivity().getApplicationContext()).get(0));
 
                 Button b = ad.getButton(AlertDialog.BUTTON_NEUTRAL);
                 b.setOnClickListener(new View.OnClickListener() {
@@ -98,7 +98,7 @@ public class pwgenDialogFragment extends DialogFragment {
                     public void onClick(View v) {
                         setPreferences();
                         TextView textView = view.findViewById(R.id.passwordText);
-                        textView.setText(pwgen.generate(callingActivity.getApplicationContext()).get(0));
+                        textView.setText(PasswordGenerator.INSTANCE.generate(callingActivity.getApplicationContext()).get(0));
                     }
                 });
             }
@@ -126,9 +126,9 @@ public class pwgenDialogFragment extends DialogFragment {
         EditText editText = getDialog().findViewById(R.id.lengthNumber);
         try {
             int length = Integer.valueOf(editText.getText().toString());
-            pwgen.setPrefs(getActivity().getApplicationContext(), preferences, length);
+            PasswordGenerator.INSTANCE.setPrefs(getActivity().getApplicationContext(), preferences, length);
         } catch(NumberFormatException e) {
-            pwgen.setPrefs(getActivity().getApplicationContext(), preferences);
+            PasswordGenerator.INSTANCE.setPrefs(getActivity().getApplicationContext(), preferences);
         }
     }
 }
diff --git a/app/src/main/java/com/zeapo/pwdstore/PasswordStore.java b/app/src/main/java/com/zeapo/pwdstore/PasswordStore.java
index 2ab94bd8..a6e399ef 100644
--- a/app/src/main/java/com/zeapo/pwdstore/PasswordStore.java
+++ b/app/src/main/java/com/zeapo/pwdstore/PasswordStore.java
@@ -116,7 +116,7 @@ public class PasswordStore extends AppCompatActivity {
             shortcutManager = getSystemService(ShortcutManager.class);
         }
         activity = this;
-        PRNGFixes.apply();
+        PRNGFixes.INSTANCE.apply();
 
         // If user opens app with permission granted then revokes and returns,
         // prevent attempt to create password list fragment
diff --git a/app/src/main/java/com/zeapo/pwdstore/crypto/PgpActivity.kt b/app/src/main/java/com/zeapo/pwdstore/crypto/PgpActivity.kt
index 53582973..63fff21d 100644
--- a/app/src/main/java/com/zeapo/pwdstore/crypto/PgpActivity.kt
+++ b/app/src/main/java/com/zeapo/pwdstore/crypto/PgpActivity.kt
@@ -1,8 +1,5 @@
 package com.zeapo.pwdstore.crypto
 
-import android.annotation.SuppressLint
-import android.app.Activity
-import android.app.AlertDialog
 import android.app.PendingIntent
 import android.content.ClipData
 import android.content.ClipboardManager
@@ -32,11 +29,12 @@ import android.widget.LinearLayout
 import android.widget.ProgressBar
 import android.widget.TextView
 import android.widget.Toast
+import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import com.zeapo.pwdstore.PasswordEntry
 import com.zeapo.pwdstore.R
 import com.zeapo.pwdstore.UserPreference
-import com.zeapo.pwdstore.pwgenDialogFragment
+import com.zeapo.pwdstore.PasswordGeneratorDialogFragment
 import com.zeapo.pwdstore.utils.Otp
 import kotlinx.android.synthetic.main.decrypt_layout.*
 import kotlinx.android.synthetic.main.encrypt_layout.*
@@ -117,7 +115,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
                 setContentView(R.layout.encrypt_layout)
 
                 generate_password?.setOnClickListener {
-                    pwgenDialogFragment().show(supportFragmentManager, "generator")
+                    PasswordGeneratorDialogFragment().show(supportFragmentManager, "generator")
                 }
 
                 title = getString(R.string.new_password_title)
@@ -324,7 +322,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
                                                             val editor = settings.edit()
                                                             editor.putBoolean("hotp_remember_check", true)
                                                             editor.putBoolean("hotp_remember_choice", true)
-                                                            editor.commit()
+                                                            editor.apply()
                                                         }
                                                     }
                                                 }
@@ -334,7 +332,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
                                                     val editor = settings.edit()
                                                     editor.putBoolean("hotp_remember_check", true)
                                                     editor.putBoolean("hotp_remember_choice", false)
-                                                    editor.commit()
+                                                    editor.apply()
                                                 }
                                             }
                                         val updateDialog = dialogBuilder.create()
@@ -439,7 +437,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
     private fun editPassword() {
         setContentView(R.layout.encrypt_layout)
         generate_password?.setOnClickListener {
-            pwgenDialogFragment().show(supportFragmentManager, "generator")
+            PasswordGeneratorDialogFragment().show(supportFragmentManager, "generator")
         }
 
         title = getString(R.string.edit_password_title)
@@ -545,26 +543,26 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
 
     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
         super.onActivityResult(requestCode, resultCode, data)
-        Log.d(TAG, "onActivityResult resultCode: " + resultCode)
+        Log.d(TAG, "onActivityResult resultCode: $resultCode")
 
         if (data == null) {
-            setResult(Activity.RESULT_CANCELED, null)
+            setResult(AppCompatActivity.RESULT_CANCELED, null)
             finish()
             return
         }
 
         // try again after user interaction
-        if (resultCode == Activity.RESULT_OK) {
+        if (resultCode == AppCompatActivity.RESULT_OK) {
             when (requestCode) {
                 REQUEST_DECRYPT -> decryptAndVerify(data)
                 REQUEST_KEY_ID -> getKeyIds(data)
                 else -> {
-                    setResult(Activity.RESULT_OK)
+                    setResult(AppCompatActivity.RESULT_OK)
                     finish()
                 }
             }
-        } else if (resultCode == Activity.RESULT_CANCELED) {
-            setResult(Activity.RESULT_CANCELED, data)
+        } else if (resultCode == AppCompatActivity.RESULT_CANCELED) {
+            setResult(AppCompatActivity.RESULT_CANCELED, data)
             finish()
         }
     }
@@ -581,7 +579,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
             return if (shown) charSequence else super.getTransformation("12345", view)
         }
 
-        @SuppressLint("ClickableViewAccessibility")
+        @Suppress("ClickableViewAccessibility")
         override fun onTouch(view: View, motionEvent: MotionEvent): Boolean {
             when (motionEvent.action) {
                 MotionEvent.ACTION_DOWN -> {
@@ -608,7 +606,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
 
         var clearAfter = 45
         try {
-            clearAfter = Integer.parseInt(settings.getString("general_show_time", "45"))
+            clearAfter = Integer.parseInt(settings.getString("general_show_time", "45") as String)
         } catch (e: NumberFormatException) {
             // ignore and keep default
         }
@@ -662,7 +660,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
         return DateUtils.getRelativeTimeSpanString(this, timeStamp.toLong() * 1000, true)
     }
 
-    @SuppressLint("StaticFieldLeak")
+    @Suppress("StaticFieldLeak")
     inner class DelayShow(val activity: PgpActivity) : AsyncTask<Void, Int, Boolean>() {
         private val pb: ProgressBar by lazy { pbLoading }
         private var skip = false
@@ -686,7 +684,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
 
         override fun onPreExecute() {
             showTime = try {
-                Integer.parseInt(settings.getString("general_show_time", "45"))
+                Integer.parseInt(settings.getString("general_show_time", "45") as String)
             } catch (e: NumberFormatException) {
                 45
             }
@@ -744,7 +742,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
             if (crypto_password_show != null) {
                 // clear password; if decrypt changed to encrypt layout via edit button, no need
                 if(passwordEntry?.hotpIsIncremented() == false) {
-                    setResult(Activity.RESULT_CANCELED)
+                    setResult(AppCompatActivity.RESULT_CANCELED)
                 }
                 passwordEntry = null
                 crypto_password_show.text = ""
@@ -788,7 +786,7 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
          * Gets the name of the password (excluding .gpg)
          */
         fun getName(fullPath: String): String {
-            return FilenameUtils.getBaseName(fullPath);
+            return FilenameUtils.getBaseName(fullPath)
         }
 
         /**
@@ -797,16 +795,16 @@ class PgpActivity : AppCompatActivity(), OpenPgpServiceConnection.OnBound {
         @JvmStatic
         fun getLongName(fullPath: String, repositoryPath: String, basename: String): String {
             var relativePath = getRelativePath(fullPath, repositoryPath)
-            if (relativePath.isNotEmpty() && relativePath != "/") {
+            return if (relativePath.isNotEmpty() && relativePath != "/") {
                 // remove preceding '/'
-                relativePath = relativePath.substring(1);
+                relativePath = relativePath.substring(1)
                 if (relativePath.endsWith('/')) {
-                    return relativePath + basename
+                    relativePath + basename
                 } else {
-                    return "$relativePath/$basename"
+                    "$relativePath/$basename"
                 }
             } else {
-                return basename
+                basename
             }
         }
     }
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/PRNGFixes.java b/app/src/main/java/com/zeapo/pwdstore/pwgen/PRNGFixes.java
deleted file mode 100644
index aabc27b2..00000000
--- a/app/src/main/java/com/zeapo/pwdstore/pwgen/PRNGFixes.java
+++ /dev/null
@@ -1,333 +0,0 @@
-package com.zeapo.pwdstore.pwgen;
-
-/*
- * This software is provided 'as-is', without any express or implied
- * warranty.  In no event will Google be held liable for any damages
- * arising from the use of this software.
- *
- * Permission is granted to anyone to use this software for any purpose,
- * including commercial applications, and to alter it and redistribute it
- * freely, as long as the origin is not misrepresented.
- */
-
-import android.os.Build;
-import android.os.Process;
-import android.util.Log;
-
-import java.io.ByteArrayOutputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.io.UnsupportedEncodingException;
-import java.security.NoSuchAlgorithmException;
-import java.security.Provider;
-import java.security.SecureRandom;
-import java.security.SecureRandomSpi;
-import java.security.Security;
-
-/**
- * Fixes for the output of the default PRNG having low entropy.
- *
- * The fixes need to be applied via {@link #apply()} before any use of Java
- * Cryptography Architecture primitives. A good place to invoke them is in the
- * application's {@code onCreate}.
- */
-public final class PRNGFixes {
-
-    private static final int VERSION_CODE_JELLY_BEAN = 16;
-    private static final int VERSION_CODE_JELLY_BEAN_MR2 = 18;
-    private static final byte[] BUILD_FINGERPRINT_AND_DEVICE_SERIAL =
-            getBuildFingerprintAndDeviceSerial();
-
-    /** Hidden constructor to prevent instantiation. */
-    private PRNGFixes() {}
-
-    /**
-     * Applies all fixes.
-     *
-     * @throws SecurityException if a fix is needed but could not be applied.
-     */
-    public static void apply() {
-        applyOpenSSLFix();
-        installLinuxPRNGSecureRandom();
-    }
-
-    /**
-     * Applies the fix for OpenSSL PRNG having low entropy. Does nothing if the
-     * fix is not needed.
-     *
-     * @throws SecurityException if the fix is needed but could not be applied.
-     */
-    private static void applyOpenSSLFix() throws SecurityException {
-        if ((Build.VERSION.SDK_INT < VERSION_CODE_JELLY_BEAN)
-                || (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2)) {
-            // No need to apply the fix
-            return;
-        }
-
-        try {
-            // Mix in the device- and invocation-specific seed.
-            Class.forName("org.apache.harmony.xnet.provider.jsse.NativeCrypto")
-                    .getMethod("RAND_seed", byte[].class)
-                    .invoke(null, generateSeed());
-
-            // Mix output of Linux PRNG into OpenSSL's PRNG
-            int bytesRead = (Integer) Class.forName(
-                    "org.apache.harmony.xnet.provider.jsse.NativeCrypto")
-                    .getMethod("RAND_load_file", String.class, long.class)
-                    .invoke(null, "/dev/urandom", 1024);
-            if (bytesRead != 1024) {
-                throw new IOException(
-                        "Unexpected number of bytes read from Linux PRNG: "
-                                + bytesRead);
-            }
-        } catch (Exception e) {
-            throw new SecurityException("Failed to seed OpenSSL PRNG", e);
-        }
-    }
-
-    /**
-     * Installs a Linux PRNG-backed {@code SecureRandom} implementation as the
-     * default. Does nothing if the implementation is already the default or if
-     * there is not need to install the implementation.
-     *
-     * @throws SecurityException if the fix is needed but could not be applied.
-     */
-    private static void installLinuxPRNGSecureRandom()
-            throws SecurityException {
-        if (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2) {
-            // No need to apply the fix
-            return;
-        }
-
-        // Install a Linux PRNG-based SecureRandom implementation as the
-        // default, if not yet installed.
-        Provider[] secureRandomProviders =
-                Security.getProviders("SecureRandom.SHA1PRNG");
-        if ((secureRandomProviders == null)
-                || (secureRandomProviders.length < 1)
-                || (!LinuxPRNGSecureRandomProvider.class.equals(
-                secureRandomProviders[0].getClass()))) {
-            Security.insertProviderAt(new LinuxPRNGSecureRandomProvider(), 1);
-        }
-
-        // Assert that new SecureRandom() and
-        // SecureRandom.getInstance("SHA1PRNG") return a SecureRandom backed
-        // by the Linux PRNG-based SecureRandom implementation.
-        SecureRandom rng1 = new SecureRandom();
-        if (!LinuxPRNGSecureRandomProvider.class.equals(
-                rng1.getProvider().getClass())) {
-            throw new SecurityException(
-                    "new SecureRandom() backed by wrong Provider: "
-                            + rng1.getProvider().getClass());
-        }
-
-        SecureRandom rng2;
-        try {
-            rng2 = SecureRandom.getInstance("SHA1PRNG");
-        } catch (NoSuchAlgorithmException e) {
-            throw new SecurityException("SHA1PRNG not available", e);
-        }
-        if (!LinuxPRNGSecureRandomProvider.class.equals(
-                rng2.getProvider().getClass())) {
-            throw new SecurityException(
-                    "SecureRandom.getInstance(\"SHA1PRNG\") backed by wrong"
-                            + " Provider: " + rng2.getProvider().getClass());
-        }
-    }
-
-    /**
-     * {@code Provider} of {@code SecureRandom} engines which pass through
-     * all requests to the Linux PRNG.
-     */
-    private static class LinuxPRNGSecureRandomProvider extends Provider {
-
-        public LinuxPRNGSecureRandomProvider() {
-            super("LinuxPRNG",
-                    1.0,
-                    "A Linux-specific random number provider that uses"
-                            + " /dev/urandom");
-            // Although /dev/urandom is not a SHA-1 PRNG, some apps
-            // explicitly request a SHA1PRNG SecureRandom and we thus need to
-            // prevent them from getting the default implementation whose output
-            // may have low entropy.
-            put("SecureRandom.SHA1PRNG", LinuxPRNGSecureRandom.class.getName());
-            put("SecureRandom.SHA1PRNG ImplementedIn", "Software");
-        }
-    }
-
-    /**
-     * {@link SecureRandomSpi} which passes all requests to the Linux PRNG
-     * ({@code /dev/urandom}).
-     */
-    public static class LinuxPRNGSecureRandom extends SecureRandomSpi {
-
-        /*
-         * IMPLEMENTATION NOTE: Requests to generate bytes and to mix in a seed
-         * are passed through to the Linux PRNG (/dev/urandom). Instances of
-         * this class seed themselves by mixing in the current time, PID, UID,
-         * build fingerprint, and hardware serial number (where available) into
-         * Linux PRNG.
-         *
-         * Concurrency: Read requests to the underlying Linux PRNG are
-         * serialized (on sLock) to ensure that multiple threads do not get
-         * duplicated PRNG output.
-         */
-
-        private static final File URANDOM_FILE = new File("/dev/urandom");
-
-        private static final Object sLock = new Object();
-
-        /**
-         * Input stream for reading from Linux PRNG or {@code null} if not yet
-         * opened.
-         */
-        private static DataInputStream sUrandomIn;
-
-        /**
-         * Output stream for writing to Linux PRNG or {@code null} if not yet
-         * opened.
-         */
-        private static OutputStream sUrandomOut;
-
-        /**
-         * Whether this engine instance has been seeded. This is needed because
-         * each instance needs to seed itself if the client does not explicitly
-         * seed it.
-         */
-        private boolean mSeeded;
-
-        @Override
-        protected void engineSetSeed(byte[] bytes) {
-            try {
-                OutputStream out;
-                synchronized (sLock) {
-                    out = getUrandomOutputStream();
-                }
-                out.write(bytes);
-                out.flush();
-            } catch (IOException e) {
-                // On a small fraction of devices /dev/urandom is not writable.
-                // Log and ignore.
-                Log.w(PRNGFixes.class.getSimpleName(),
-                        "Failed to mix seed into " + URANDOM_FILE);
-            } finally {
-                mSeeded = true;
-            }
-        }
-
-        @SuppressWarnings("SynchronizationOnLocalVariableOrMethodParameter")
-        @Override
-        protected void engineNextBytes(byte[] bytes) {
-            if (!mSeeded) {
-                // Mix in the device- and invocation-specific seed.
-                engineSetSeed(generateSeed());
-            }
-
-            try {
-                DataInputStream in;
-                synchronized (sLock) {
-                    in = getUrandomInputStream();
-                }
-                synchronized (in) {
-                    in.readFully(bytes);
-                }
-            } catch (IOException e) {
-                throw new SecurityException(
-                        "Failed to read from " + URANDOM_FILE, e);
-            }
-        }
-
-        @Override
-        protected byte[] engineGenerateSeed(int size) {
-            byte[] seed = new byte[size];
-            engineNextBytes(seed);
-            return seed;
-        }
-
-        private DataInputStream getUrandomInputStream() {
-            synchronized (sLock) {
-                if (sUrandomIn == null) {
-                    // NOTE: Consider inserting a BufferedInputStream between
-                    // DataInputStream and FileInputStream if you need higher
-                    // PRNG output performance and can live with future PRNG
-                    // output being pulled into this process prematurely.
-                    try {
-                        sUrandomIn = new DataInputStream(
-                                new FileInputStream(URANDOM_FILE));
-                    } catch (IOException e) {
-                        throw new SecurityException("Failed to open "
-                                + URANDOM_FILE + " for reading", e);
-                    }
-                }
-                return sUrandomIn;
-            }
-        }
-
-        private OutputStream getUrandomOutputStream() throws IOException {
-            synchronized (sLock) {
-                if (sUrandomOut == null) {
-                    sUrandomOut = new FileOutputStream(URANDOM_FILE);
-                }
-                return sUrandomOut;
-            }
-        }
-    }
-
-    /**
-     * Generates a device- and invocation-specific seed to be mixed into the
-     * Linux PRNG.
-     */
-    private static byte[] generateSeed() {
-        try {
-            ByteArrayOutputStream seedBuffer = new ByteArrayOutputStream();
-            DataOutputStream seedBufferOut =
-                    new DataOutputStream(seedBuffer);
-            seedBufferOut.writeLong(System.currentTimeMillis());
-            seedBufferOut.writeLong(System.nanoTime());
-            seedBufferOut.writeInt(Process.myPid());
-            seedBufferOut.writeInt(Process.myUid());
-            seedBufferOut.write(BUILD_FINGERPRINT_AND_DEVICE_SERIAL);
-            seedBufferOut.close();
-            return seedBuffer.toByteArray();
-        } catch (IOException e) {
-            throw new SecurityException("Failed to generate seed", e);
-        }
-    }
-
-    /**
-     * Gets the hardware serial number of this device.
-     *
-     * @return serial number or {@code null} if not available.
-     */
-    private static String getDeviceSerialNumber() {
-        // We're using the Reflection API because Build.SERIAL is only available
-        // since API Level 9 (Gingerbread, Android 2.3).
-        try {
-            return (String) Build.class.getField("SERIAL").get(null);
-        } catch (Exception ignored) {
-            return null;
-        }
-    }
-
-    private static byte[] getBuildFingerprintAndDeviceSerial() {
-        StringBuilder result = new StringBuilder();
-        String fingerprint = Build.FINGERPRINT;
-        if (fingerprint != null) {
-            result.append(fingerprint);
-        }
-        String serial = getDeviceSerialNumber();
-        if (serial != null) {
-            result.append(serial);
-        }
-        try {
-            return result.toString().getBytes("UTF-8");
-        } catch (UnsupportedEncodingException e) {
-            throw new RuntimeException("UTF-8 encoding not supported");
-        }
-    }
-}
\ No newline at end of file
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/PRNGFixes.kt b/app/src/main/java/com/zeapo/pwdstore/pwgen/PRNGFixes.kt
new file mode 100644
index 00000000..98c3735f
--- /dev/null
+++ b/app/src/main/java/com/zeapo/pwdstore/pwgen/PRNGFixes.kt
@@ -0,0 +1,310 @@
+package com.zeapo.pwdstore.pwgen
+
+/*
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will Google be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, as long as the origin is not misrepresented.
+ */
+
+import android.os.Build
+import android.os.Process
+import android.util.Log
+
+import java.io.ByteArrayOutputStream
+import java.io.DataInputStream
+import java.io.DataOutputStream
+import java.io.File
+import java.io.FileInputStream
+import java.io.FileOutputStream
+import java.io.IOException
+import java.io.OutputStream
+import java.io.UnsupportedEncodingException
+import java.security.NoSuchAlgorithmException
+import java.security.Provider
+import java.security.SecureRandom
+import java.security.SecureRandomSpi
+import java.security.Security
+
+/**
+ * Fixes for the output of the default PRNG having low entropy.
+ *
+ * The fixes need to be applied via [.apply] before any use of Java
+ * Cryptography Architecture primitives. A good place to invoke them is in the
+ * application's `onCreate`.
+ */
+object PRNGFixes {
+
+    private const val VERSION_CODE_JELLY_BEAN_MR2 = 18
+    private val BUILD_FINGERPRINT_AND_DEVICE_SERIAL = buildFingerprintAndDeviceSerial
+
+    private val buildFingerprintAndDeviceSerial: ByteArray
+        get() {
+            val result = StringBuilder()
+            val fingerprint = Build.FINGERPRINT
+            if (fingerprint != null) {
+                result.append(fingerprint)
+            }
+            // TODO: Build#SERIAL is deprecated and should be removed or replaced
+            val serial = Build.SERIAL
+            if (serial != null) {
+                result.append(serial)
+            }
+            try {
+                return result.toString().toByteArray(charset("UTF-8"))
+            } catch (e: UnsupportedEncodingException) {
+                throw RuntimeException("UTF-8 encoding not supported")
+            }
+        }
+
+    /**
+     * Applies all fixes.
+     *
+     * @throws SecurityException if a fix is needed but could not be applied.
+     */
+    fun apply() {
+        applyOpenSSLFix()
+        installLinuxPRNGSecureRandom()
+    }
+
+    /**
+     * Applies the fix for OpenSSL PRNG having low entropy. Does nothing if the
+     * fix is not needed.
+     *
+     * @throws SecurityException if the fix is needed but could not be applied.
+     */
+    @Throws(SecurityException::class)
+    private fun applyOpenSSLFix() {
+        if (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2) {
+            // No need to apply the fix
+            return
+        }
+
+        try {
+            // Mix in the device- and invocation-specific seed.
+            Class.forName("org.apache.harmony.xnet.provider.jsse.NativeCrypto")
+                .getMethod("RAND_seed", ByteArray::class.java)
+                .invoke(null, generateSeed())
+
+            // Mix output of Linux PRNG into OpenSSL's PRNG
+            val bytesRead = Class.forName(
+                "org.apache.harmony.xnet.provider.jsse.NativeCrypto"
+            )
+                .getMethod("RAND_load_file", String::class.java, Long::class.javaPrimitiveType)
+                .invoke(null, "/dev/urandom", 1024) as Int
+            if (bytesRead != 1024) {
+                throw IOException(
+                    "Unexpected number of bytes read from Linux PRNG: $bytesRead"
+                )
+            }
+        } catch (e: Exception) {
+            throw SecurityException("Failed to seed OpenSSL PRNG", e)
+        }
+    }
+
+    /**
+     * Installs a Linux PRNG-backed `SecureRandom` implementation as the
+     * default. Does nothing if the implementation is already the default or if
+     * there is not need to install the implementation.
+     *
+     * @throws SecurityException if the fix is needed but could not be applied.
+     */
+    @Throws(SecurityException::class)
+    private fun installLinuxPRNGSecureRandom() {
+        if (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2) {
+            // No need to apply the fix
+            return
+        }
+
+        // Install a Linux PRNG-based SecureRandom implementation as the
+        // default, if not yet installed.
+        val secureRandomProviders = Security.getProviders("SecureRandom.SHA1PRNG")
+        if (secureRandomProviders == null
+            || secureRandomProviders.isEmpty()
+            || LinuxPRNGSecureRandomProvider::class.java != secureRandomProviders[0].javaClass
+        ) {
+            Security.insertProviderAt(LinuxPRNGSecureRandomProvider(), 1)
+        }
+
+        // Assert that new SecureRandom() and
+        // SecureRandom.getInstance("SHA1PRNG") return a SecureRandom backed
+        // by the Linux PRNG-based SecureRandom implementation.
+        val rng1 = SecureRandom()
+        if (LinuxPRNGSecureRandomProvider::class.java != rng1.provider.javaClass) {
+            throw SecurityException(
+                "new SecureRandom() backed by wrong Provider: " + rng1.provider.javaClass
+            )
+        }
+
+        val rng2: SecureRandom
+        try {
+            rng2 = SecureRandom.getInstance("SHA1PRNG")
+        } catch (e: NoSuchAlgorithmException) {
+            throw SecurityException("SHA1PRNG not available", e)
+        }
+
+        if (LinuxPRNGSecureRandomProvider::class.java != rng2.provider.javaClass) {
+            throw SecurityException(
+                "SecureRandom.getInstance(\"SHA1PRNG\") backed by wrong"
+                    + " Provider: " + rng2.provider.javaClass
+            )
+        }
+    }
+
+    /**
+     * `Provider` of `SecureRandom` engines which pass through
+     * all requests to the Linux PRNG.
+     */
+    private class LinuxPRNGSecureRandomProvider :
+        Provider("LinuxPRNG", 1.0, "A Linux-specific random number provider that uses" + " /dev/urandom") {
+        init {
+            // Although /dev/urandom is not a SHA-1 PRNG, some apps
+            // explicitly request a SHA1PRNG SecureRandom and we thus need to
+            // prevent them from getting the default implementation whose output
+            // may have low entropy.
+            put("SecureRandom.SHA1PRNG", LinuxPRNGSecureRandom::class.java.name)
+            put("SecureRandom.SHA1PRNG ImplementedIn", "Software")
+        }
+    }
+
+    /**
+     * [SecureRandomSpi] which passes all requests to the Linux PRNG
+     * (`/dev/urandom`).
+     */
+    class LinuxPRNGSecureRandom : SecureRandomSpi() {
+
+        /**
+         * Whether this engine instance has been seeded. This is needed because
+         * each instance needs to seed itself if the client does not explicitly
+         * seed it.
+         */
+        private var mSeeded: Boolean = false
+
+        private// NOTE: Consider inserting a BufferedInputStream between
+        // DataInputStream and FileInputStream if you need higher
+        // PRNG output performance and can live with future PRNG
+        // output being pulled into this process prematurely.
+        val urandomInputStream: DataInputStream
+            get() = synchronized(sLock) {
+                if (sUrandomIn == null) {
+                    try {
+                        sUrandomIn = DataInputStream(
+                            FileInputStream(URANDOM_FILE)
+                        )
+                    } catch (e: IOException) {
+                        throw SecurityException(
+                            "Failed to open "
+                                + URANDOM_FILE + " for reading", e
+                        )
+                    }
+                }
+                return sUrandomIn as DataInputStream
+            }
+
+        private val urandomOutputStream: OutputStream
+            @Throws(IOException::class)
+            get() = synchronized(sLock) {
+                if (sUrandomOut == null) {
+                    sUrandomOut = FileOutputStream(URANDOM_FILE)
+                }
+                return sUrandomOut as OutputStream
+            }
+
+        @Synchronized
+        override fun engineSetSeed(bytes: ByteArray) {
+            try {
+                val out: OutputStream = urandomOutputStream
+                out.write(bytes)
+                out.flush()
+            } catch (e: IOException) {
+                // On a small fraction of devices /dev/urandom is not writable.
+                // Log and ignore.
+                Log.w(
+                    PRNGFixes::class.java.simpleName,
+                    "Failed to mix seed into $URANDOM_FILE"
+                )
+            } finally {
+                mSeeded = true
+            }
+        }
+
+        @Synchronized
+        override fun engineNextBytes(bytes: ByteArray) {
+            if (!mSeeded) {
+                // Mix in the device- and invocation-specific seed.
+                engineSetSeed(generateSeed())
+            }
+
+            try {
+                val `in`: DataInputStream = urandomInputStream
+                synchronized(`in`) {
+                    `in`.readFully(bytes)
+                }
+            } catch (e: IOException) {
+                throw SecurityException(
+                    "Failed to read from $URANDOM_FILE", e
+                )
+            }
+        }
+
+        override fun engineGenerateSeed(size: Int): ByteArray {
+            val seed = ByteArray(size)
+            engineNextBytes(seed)
+            return seed
+        }
+
+        companion object {
+
+            /*
+         * IMPLEMENTATION NOTE: Requests to generate bytes and to mix in a seed
+         * are passed through to the Linux PRNG (/dev/urandom). Instances of
+         * this class seed themselves by mixing in the current time, PID, UID,
+         * build fingerprint, and hardware serial number (where available) into
+         * Linux PRNG.
+         *
+         * Concurrency: Read requests to the underlying Linux PRNG are
+         * serialized (on sLock) to ensure that multiple threads do not get
+         * duplicated PRNG output.
+         */
+
+            private val URANDOM_FILE = File("/dev/urandom")
+
+            private val sLock = Any()
+
+            /**
+             * Input stream for reading from Linux PRNG or `null` if not yet
+             * opened.
+             */
+            private var sUrandomIn: DataInputStream? = null
+
+            /**
+             * Output stream for writing to Linux PRNG or `null` if not yet
+             * opened.
+             */
+            private var sUrandomOut: OutputStream? = null
+        }
+    }
+
+    /**
+     * Generates a device- and invocation-specific seed to be mixed into the
+     * Linux PRNG.
+     */
+    private fun generateSeed(): ByteArray {
+        try {
+            val seedBuffer = ByteArrayOutputStream()
+            val seedBufferOut = DataOutputStream(seedBuffer)
+            seedBufferOut.writeLong(System.currentTimeMillis())
+            seedBufferOut.writeLong(System.nanoTime())
+            seedBufferOut.writeInt(Process.myPid())
+            seedBufferOut.writeInt(Process.myUid())
+            seedBufferOut.write(BUILD_FINGERPRINT_AND_DEVICE_SERIAL)
+            seedBufferOut.close()
+            return seedBuffer.toByteArray()
+        } catch (e: IOException) {
+            throw SecurityException("Failed to generate seed", e)
+        }
+    }
+}
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/PasswordGenerator.kt b/app/src/main/java/com/zeapo/pwdstore/pwgen/PasswordGenerator.kt
new file mode 100644
index 00000000..0374236c
--- /dev/null
+++ b/app/src/main/java/com/zeapo/pwdstore/pwgen/PasswordGenerator.kt
@@ -0,0 +1,125 @@
+package com.zeapo.pwdstore.pwgen
+
+import android.content.Context
+import android.content.SharedPreferences
+
+import java.util.ArrayList
+
+object PasswordGenerator {
+    internal val DIGITS = 0x0001
+    internal val UPPERS = 0x0002
+    internal val SYMBOLS = 0x0004
+    internal val AMBIGUOUS = 0x0008
+    internal val NO_VOWELS = 0x0010
+
+    internal val DIGITS_STR = "0123456789"
+    internal val UPPERS_STR = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    internal val LOWERS_STR = "abcdefghijklmnopqrstuvwxyz"
+    internal val SYMBOLS_STR = "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~"
+    internal val AMBIGUOUS_STR = "B8G6I1l0OQDS5Z2"
+    internal val VOWELS_STR = "01aeiouyAEIOUY"
+
+    // No a, c, n, h, H, C, 1, N
+    private val pwOptions = "0ABsvy"
+
+    /**
+     * Sets password generation preferences.
+     *
+     * @param ctx     context from which to retrieve SharedPreferences from
+     * preferences file 'PasswordGenerator'
+     * @param argv    options for password generation
+     * <table summary="options for password generation">
+     * <tr><td>Option</td><td>Description</td></tr>
+     * <tr><td>0</td><td>don't include numbers</td></tr>
+     * <tr><td>A</td><td>don't include uppercase letters</td></tr>
+     * <tr><td>B</td><td>don't include ambiguous charactersl</td></tr>
+     * <tr><td>s</td><td>generate completely random passwords</td></tr>
+     * <tr><td>v</td><td>don't include vowels</td></tr>
+     * <tr><td>y</td><td>include at least one symbol</td></tr>
+    </table> *
+     * @param numArgv numerical options for password generation: length of
+     * generated passwords followed by number of passwords to
+     * generate
+     * @return `false` if a numerical options is invalid,
+     * `true` otherwise
+     */
+    fun setPrefs(ctx: Context, argv: ArrayList<String>, vararg numArgv: Int): Boolean {
+        val prefs = ctx.getSharedPreferences("PasswordGenerator", Context.MODE_PRIVATE)
+        val editor = prefs.edit()
+
+        for (option in pwOptions.toCharArray()) {
+            if (argv.contains(option.toString())) {
+                editor.putBoolean(option.toString(), true)
+                argv.remove(option.toString())
+            } else {
+                editor.putBoolean(option.toString(), false)
+            }
+        }
+        var i = 0
+        while (i < numArgv.size && i < 2) {
+            if (numArgv[i] <= 0) {
+                // Invalid password length or number of passwords
+                return false
+            }
+            val name = if (i == 0) "length" else "num"
+            editor.putInt(name, numArgv[i])
+            i++
+        }
+        editor.apply()
+        return true
+    }
+
+    /**
+     * Generates passwords using the preferences set by
+     * [.setPrefs].
+     *
+     * @param ctx context from which to retrieve SharedPreferences from
+     * preferences file 'PasswordGenerator'
+     * @return list of generated passwords
+     */
+    fun generate(ctx: Context): ArrayList<String> {
+        val prefs = ctx.getSharedPreferences("PasswordGenerator", Context.MODE_PRIVATE)
+
+        var phonemes = true
+        var pwgenFlags = DIGITS or UPPERS
+
+        for (option in pwOptions.toCharArray()) {
+            if (prefs.getBoolean(option.toString(), false)) {
+                when (option) {
+                    '0' -> pwgenFlags = pwgenFlags and DIGITS.inv()
+                    'A' -> pwgenFlags = pwgenFlags and UPPERS.inv()
+                    'B' -> pwgenFlags = pwgenFlags or AMBIGUOUS
+                    's' -> phonemes = false
+                    'y' -> pwgenFlags = pwgenFlags or SYMBOLS
+                    'v' -> {
+                        phonemes = false
+                        pwgenFlags = pwgenFlags or NO_VOWELS // | DIGITS | UPPERS;
+                    }
+                }// pwgenFlags = DIGITS | UPPERS;
+            }
+        }
+
+        val length = prefs.getInt("length", 8)
+        if (length < 5) {
+            phonemes = false
+        }
+        if (length <= 2) {
+            pwgenFlags = pwgenFlags and UPPERS.inv()
+        }
+        if (length <= 1) {
+            pwgenFlags = pwgenFlags and DIGITS.inv()
+        }
+
+        val passwords = ArrayList<String>()
+        val num = prefs.getInt("num", 1)
+        for (i in 0 until num) {
+            if (phonemes) {
+                passwords.add(Phonemes.phonemes(length, pwgenFlags))
+            } else {
+                passwords.add(RandomPasswordGenerator.rand(length, pwgenFlags))
+            }
+        }
+        return passwords
+    }
+}
+
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/Phonemes.kt b/app/src/main/java/com/zeapo/pwdstore/pwgen/Phonemes.kt
new file mode 100644
index 00000000..4ec204bc
--- /dev/null
+++ b/app/src/main/java/com/zeapo/pwdstore/pwgen/Phonemes.kt
@@ -0,0 +1,208 @@
+package com.zeapo.pwdstore.pwgen
+
+internal object Phonemes {
+    private const val CONSONANT = 0x0001
+    private const val VOWEL = 0x0002
+    private const val DIPTHONG = 0x0004
+    private const val NOT_FIRST = 0x0008
+
+    private val elements = arrayOf(
+        Element("a", VOWEL),
+        Element("ae", VOWEL or DIPTHONG),
+        Element("ah", VOWEL or DIPTHONG),
+        Element("ai", VOWEL or DIPTHONG),
+        Element("b", CONSONANT),
+        Element("c", CONSONANT),
+        Element("ch", CONSONANT or DIPTHONG),
+        Element("d", CONSONANT),
+        Element("e", VOWEL),
+        Element("ee", VOWEL or DIPTHONG),
+        Element("ei", VOWEL or DIPTHONG),
+        Element("f", CONSONANT),
+        Element("g", CONSONANT),
+        Element("gh", CONSONANT or DIPTHONG or NOT_FIRST),
+        Element("h", CONSONANT),
+        Element("i", VOWEL),
+        Element("ie", VOWEL or DIPTHONG),
+        Element("j", CONSONANT),
+        Element("k", CONSONANT),
+        Element("l", CONSONANT),
+        Element("m", CONSONANT),
+        Element("n", CONSONANT),
+        Element("ng", CONSONANT or DIPTHONG or NOT_FIRST),
+        Element("o", VOWEL),
+        Element("oh", VOWEL or DIPTHONG),
+        Element("oo", VOWEL or DIPTHONG),
+        Element("p", CONSONANT),
+        Element("ph", CONSONANT or DIPTHONG),
+        Element("qu", CONSONANT or DIPTHONG),
+        Element("r", CONSONANT),
+        Element("s", CONSONANT),
+        Element("sh", CONSONANT or DIPTHONG),
+        Element("t", CONSONANT),
+        Element("th", CONSONANT or DIPTHONG),
+        Element("u", VOWEL),
+        Element("v", CONSONANT),
+        Element("w", CONSONANT),
+        Element("x", CONSONANT),
+        Element("y", CONSONANT),
+        Element("z", CONSONANT)
+    )
+
+    private val NUM_ELEMENTS = elements.size
+
+    private class Element internal constructor(internal var str: String, internal var flags: Int)
+
+    /**
+     * Generates a human-readable password.
+     *
+     * @param size    length of password to generate
+     * @param pwFlags flag field where set bits indicate conditions the
+     * generated password must meet
+     * <table summary="bits of flag field">
+     * <tr><td>Bit</td><td>Condition</td></tr>
+     * <tr><td>0</td><td>include at least one number</td></tr>
+     * <tr><td>1</td><td>include at least one uppercase letter</td></tr>
+     * <tr><td>2</td><td>include at least one symbol</td></tr>
+     * <tr><td>3</td><td>don't include ambiguous characters</td></tr>
+    </table> *
+     * @return the generated password
+     */
+    fun phonemes(size: Int, pwFlags: Int): String {
+        var password: String
+        var curSize: Int
+        var i: Int
+        var length: Int
+        var flags: Int
+        var featureFlags: Int
+        var prev: Int
+        var shouldBe: Int
+        var first: Boolean
+        var str: String
+        var cha: Char
+
+        do {
+            password = ""
+            featureFlags = pwFlags
+            curSize = 0
+            prev = 0
+            first = true
+
+            shouldBe = if (RandomNumberGenerator.number(2) == 1) VOWEL else CONSONANT
+
+            while (curSize < size) {
+                i = RandomNumberGenerator.number(NUM_ELEMENTS)
+                str = elements[i].str
+                length = str.length
+                flags = elements[i].flags
+                // Filter on the basic type of the next Element
+                if (flags and shouldBe == 0) {
+                    continue
+                }
+                // Handle the NOT_FIRST flag
+                if (first && flags and NOT_FIRST > 0) {
+                    continue
+                }
+                // Don't allow VOWEL followed a Vowel/Dipthong pair
+                if (prev and VOWEL > 0 && flags and VOWEL > 0
+                    && flags and DIPTHONG > 0
+                ) {
+                    continue
+                }
+                // Don't allow us to overflow the buffer
+                if (length > size - curSize) {
+                    continue
+                }
+                // OK, we found an Element which matches our criteria, let's do
+                // it
+                password += str
+
+                // Handle UPPERS
+                if (pwFlags and PasswordGenerator.UPPERS > 0) {
+                    if ((first || flags and CONSONANT > 0) && RandomNumberGenerator.number(10) < 2) {
+                        val index = password.length - length
+                        password = password.substring(0, index) + str.toUpperCase()
+                        featureFlags = featureFlags and PasswordGenerator.UPPERS.inv()
+                    }
+                }
+
+                // Handle the AMBIGUOUS flag
+                if (pwFlags and PasswordGenerator.AMBIGUOUS > 0) {
+                    for (ambiguous in PasswordGenerator.AMBIGUOUS_STR.toCharArray()) {
+                        if (password.contains(ambiguous.toString())) {
+                            password = password.substring(0, curSize)
+                            break
+                        }
+                    }
+                    if (password.length == curSize)
+                        continue
+                }
+
+                curSize += length
+
+                // Time to stop?
+                if (curSize >= size)
+                    break
+
+                // Handle DIGITS
+                if (pwFlags and PasswordGenerator.DIGITS > 0) {
+                    if (!first && RandomNumberGenerator.number(10) < 3) {
+                        var `val`: String
+                        do {
+                            cha = Character.forDigit(RandomNumberGenerator.number(10), 10)
+                            `val` = cha.toString()
+                        } while (pwFlags and PasswordGenerator.AMBIGUOUS > 0 && PasswordGenerator.AMBIGUOUS_STR.contains(
+                                `val`
+                            )
+                        )
+                        password += `val`
+                        curSize++
+
+                        featureFlags = featureFlags and PasswordGenerator.DIGITS.inv()
+
+                        first = true
+                        prev = 0
+                        shouldBe = if (RandomNumberGenerator.number(2) == 1) VOWEL else CONSONANT
+                        continue
+                    }
+                }
+
+                // Handle SYMBOLS
+                if (pwFlags and PasswordGenerator.SYMBOLS > 0) {
+                    if (!first && RandomNumberGenerator.number(10) < 2) {
+                        var `val`: String
+                        var num: Int
+                        do {
+                            num = RandomNumberGenerator.number(PasswordGenerator.SYMBOLS_STR.length)
+                            cha = PasswordGenerator.SYMBOLS_STR.toCharArray()[num]
+                            `val` = cha.toString()
+                        } while (pwFlags and PasswordGenerator.AMBIGUOUS > 0 && PasswordGenerator.AMBIGUOUS_STR.contains(
+                                `val`
+                            )
+                        )
+                        password += `val`
+                        curSize++
+
+                        featureFlags = featureFlags and PasswordGenerator.SYMBOLS.inv()
+                    }
+                }
+
+                // OK, figure out what the next Element should be
+                shouldBe = if (shouldBe == CONSONANT) {
+                    VOWEL
+                } else {
+                    if (prev and VOWEL > 0 || flags and DIPTHONG > 0
+                        || RandomNumberGenerator.number(10) > 3
+                    ) {
+                        CONSONANT
+                    } else {
+                        VOWEL
+                    }
+                }
+                prev = flags
+                first = false
+            }
+        } while (featureFlags and (PasswordGenerator.UPPERS or PasswordGenerator.DIGITS or PasswordGenerator.SYMBOLS) > 0)
+        return password
+    }
+}
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/RandomNumberGenerator.kt b/app/src/main/java/com/zeapo/pwdstore/pwgen/RandomNumberGenerator.kt
new file mode 100644
index 00000000..e208bc75
--- /dev/null
+++ b/app/src/main/java/com/zeapo/pwdstore/pwgen/RandomNumberGenerator.kt
@@ -0,0 +1,26 @@
+package com.zeapo.pwdstore.pwgen
+
+import java.security.NoSuchAlgorithmException
+import java.security.SecureRandom
+
+internal object RandomNumberGenerator {
+    private var random: SecureRandom
+
+    init {
+        try {
+            random = SecureRandom.getInstance("SHA1PRNG")
+        } catch (e: NoSuchAlgorithmException) {
+            throw SecurityException("SHA1PRNG not available", e)
+        }
+    }
+
+    /**
+     * Generate a random number n, where 0 &lt;= n &lt; maxNum.
+     *
+     * @param maxNum the bound on the random number to be returned
+     * @return the generated random number
+     */
+    fun number(maxNum: Int): Int {
+        return random.nextInt(maxNum)
+    }
+}
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/RandomPasswordGenerator.kt b/app/src/main/java/com/zeapo/pwdstore/pwgen/RandomPasswordGenerator.kt
new file mode 100644
index 00000000..632fa579
--- /dev/null
+++ b/app/src/main/java/com/zeapo/pwdstore/pwgen/RandomPasswordGenerator.kt
@@ -0,0 +1,72 @@
+package com.zeapo.pwdstore.pwgen
+
+internal object RandomPasswordGenerator {
+
+    /**
+     * Generates a completely random password.
+     *
+     * @param size    length of password to generate
+     * @param pwFlags flag field where set bits indicate conditions the
+     * generated password must meet
+     * <table summary ="bits of flag field">
+     * <tr><td>Bit</td><td>Condition</td></tr>
+     * <tr><td>0</td><td>include at least one number</td></tr>
+     * <tr><td>1</td><td>include at least one uppercase letter</td></tr>
+     * <tr><td>2</td><td>include at least one symbol</td></tr>
+     * <tr><td>3</td><td>don't include ambiguous characters</td></tr>
+     * <tr><td>4</td><td>don't include vowels</td></tr>
+    </table> *
+     * @return the generated password
+     */
+    fun rand(size: Int, pwFlags: Int): String {
+        var password: String
+        var cha: Char
+        var i: Int
+        var featureFlags: Int
+        var num: Int
+        var `val`: String
+
+        var bank = ""
+        if (pwFlags and PasswordGenerator.DIGITS > 0) {
+            bank += PasswordGenerator.DIGITS_STR
+        }
+        if (pwFlags and PasswordGenerator.UPPERS > 0) {
+            bank += PasswordGenerator.UPPERS_STR
+        }
+        bank += PasswordGenerator.LOWERS_STR
+        if (pwFlags and PasswordGenerator.SYMBOLS > 0) {
+            bank += PasswordGenerator.SYMBOLS_STR
+        }
+        do {
+            password = ""
+            featureFlags = pwFlags
+            i = 0
+            while (i < size) {
+                num = RandomNumberGenerator.number(bank.length)
+                cha = bank.toCharArray()[num]
+                `val` = cha.toString()
+                if (pwFlags and PasswordGenerator.AMBIGUOUS > 0 && PasswordGenerator.AMBIGUOUS_STR.contains(
+                        `val`
+                    )
+                ) {
+                    continue
+                }
+                if (pwFlags and PasswordGenerator.NO_VOWELS > 0 && PasswordGenerator.VOWELS_STR.contains(`val`)) {
+                    continue
+                }
+                password += `val`
+                i++
+                if (PasswordGenerator.DIGITS_STR.contains(`val`)) {
+                    featureFlags = featureFlags and PasswordGenerator.DIGITS.inv()
+                }
+                if (PasswordGenerator.UPPERS_STR.contains(`val`)) {
+                    featureFlags = featureFlags and PasswordGenerator.UPPERS.inv()
+                }
+                if (PasswordGenerator.SYMBOLS_STR.contains(`val`)) {
+                    featureFlags = featureFlags and PasswordGenerator.SYMBOLS.inv()
+                }
+            }
+        } while (featureFlags and (PasswordGenerator.UPPERS or PasswordGenerator.DIGITS or PasswordGenerator.SYMBOLS) > 0)
+        return password
+    }
+}
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/pw_phonemes.java b/app/src/main/java/com/zeapo/pwdstore/pwgen/pw_phonemes.java
deleted file mode 100644
index 297c21c5..00000000
--- a/app/src/main/java/com/zeapo/pwdstore/pwgen/pw_phonemes.java
+++ /dev/null
@@ -1,206 +0,0 @@
-package com.zeapo.pwdstore.pwgen;
-
-class pw_phonemes {
-    private static final int CONSONANT  = 0x0001;
-    private static final int VOWEL      = 0x0002;
-    private static final int DIPTHONG   = 0x0004;
-    private static final int NOT_FIRST  = 0x0008;
-
-    private static final element elements[] = {
-            new element("a", VOWEL),
-            new element("ae", VOWEL | DIPTHONG),
-            new element("ah", VOWEL | DIPTHONG),
-            new element("ai", VOWEL | DIPTHONG),
-            new element("b",  CONSONANT),
-            new element("c", CONSONANT),
-            new element("ch", CONSONANT | DIPTHONG),
-            new element("d", CONSONANT),
-            new element("e", VOWEL),
-            new element("ee", VOWEL | DIPTHONG),
-            new element("ei", VOWEL | DIPTHONG),
-            new element("f", CONSONANT),
-            new element("g", CONSONANT),
-            new element("gh", CONSONANT | DIPTHONG | NOT_FIRST),
-            new element("h", CONSONANT),
-            new element("i", VOWEL),
-            new element("ie", VOWEL | DIPTHONG),
-            new element("j", CONSONANT),
-            new element("k", CONSONANT),
-            new element("l", CONSONANT),
-            new element("m", CONSONANT),
-            new element("n", CONSONANT),
-            new element("ng", CONSONANT | DIPTHONG | NOT_FIRST),
-            new element("o", VOWEL),
-            new element("oh", VOWEL | DIPTHONG),
-            new element("oo", VOWEL | DIPTHONG),
-            new element("p", CONSONANT),
-            new element("ph", CONSONANT | DIPTHONG),
-            new element("qu", CONSONANT | DIPTHONG),
-            new element("r", CONSONANT),
-            new element("s", CONSONANT),
-            new element("sh", CONSONANT | DIPTHONG),
-            new element("t", CONSONANT),
-            new element("th", CONSONANT | DIPTHONG),
-            new element("u", VOWEL),
-            new element("v", CONSONANT),
-            new element("w", CONSONANT),
-            new element("x", CONSONANT),
-            new element("y", CONSONANT),
-            new element("z", CONSONANT)
-    };
-
-    private static class element {
-        String str;
-        int flags;
-        element(String str, int flags) {
-            this.str = str;
-            this.flags = flags;
-        }
-    }
-
-    private static final int NUM_ELEMENTS = elements.length;
-
-    /**
-     * Generates a human-readable password.
-     *
-     * @param size    length of password to generate
-     * @param pwFlags flag field where set bits indicate conditions the
-     *                generated password must meet
-     *                <table summary="bits of flag field">
-     *                <tr><td>Bit</td><td>Condition</td></tr>
-     *                <tr><td>0</td><td>include at least one number</td></tr>
-     *                <tr><td>1</td><td>include at least one uppercase letter</td></tr>
-     *                <tr><td>2</td><td>include at least one symbol</td></tr>
-     *                <tr><td>3</td><td>don't include ambiguous characters</td></tr>
-     *                </table>
-     * @return the generated password
-     */
-    public static String phonemes(int size, int pwFlags) {
-        String password;
-        int curSize, i, length, flags, featureFlags, prev, shouldBe;
-        boolean first;
-        String str;
-        char cha;
-
-        do {
-            password = "";
-            featureFlags = pwFlags;
-            curSize = 0;
-            prev = 0;
-            first = true;
-
-            shouldBe = randnum.number(2) == 1 ? VOWEL : CONSONANT;
-
-            while (curSize < size) {
-                i = randnum.number(NUM_ELEMENTS);
-                str = elements[i].str;
-                length = str.length();
-                flags = elements[i].flags;
-                // Filter on the basic type of the next element
-                if ((flags & shouldBe) == 0) {
-                    continue;
-                }
-                // Handle the NOT_FIRST flag
-                if (first && (flags & NOT_FIRST) > 0) {
-                    continue;
-                }
-                // Don't allow VOWEL followed a Vowel/Dipthong pair
-                if ((prev & VOWEL) > 0 && (flags & VOWEL) > 0
-                        && (flags & DIPTHONG) > 0) {
-                    continue;
-                }
-                // Don't allow us to overflow the buffer
-                if (length > size - curSize) {
-                    continue;
-                }
-                // OK, we found an element which matches our criteria, let's do
-                // it
-                password += str;
-
-                // Handle UPPERS
-                if ((pwFlags & pwgen.UPPERS) > 0) {
-                    if ((first || (flags & CONSONANT) > 0)
-                            && (randnum.number(10) < 2)) {
-                        int index = password.length() - length;
-                        password = password.substring(0, index)
-                                + str.toUpperCase();
-                        featureFlags &= ~pwgen.UPPERS;
-                    }
-                }
-
-                // Handle the AMBIGUOUS flag
-                if ((pwFlags & pwgen.AMBIGUOUS) > 0) {
-                    for (char ambiguous : pwgen.AMBIGUOUS_STR.toCharArray()) {
-                        if (password.contains(String.valueOf(ambiguous))) {
-                            password = password.substring(0, curSize);
-                            break;
-                        }
-                    }
-                    if (password.length() == curSize)
-                        continue;
-                }
-
-                curSize += length;
-
-                // Time to stop?
-                if (curSize >= size)
-                    break;
-
-                // Handle DIGITS
-                if ((pwFlags & pwgen.DIGITS) > 0) {
-                    if (!first && (randnum.number(10) < 3)) {
-                        String val;
-                        do {
-                            cha = Character.forDigit(randnum.number(10), 10);
-                            val = String.valueOf(cha);
-                        } while ((pwFlags & pwgen.AMBIGUOUS) > 0
-                                && pwgen.AMBIGUOUS_STR.contains(val));
-                        password += val;
-                        curSize++;
-
-                        featureFlags &= ~pwgen.DIGITS;
-
-                        first = true;
-                        prev = 0;
-                        shouldBe = randnum.number(2) == 1 ? VOWEL : CONSONANT;
-                        continue;
-                    }
-                }
-
-                // Handle SYMBOLS
-                if ((pwFlags & pwgen.SYMBOLS) > 0) {
-                    if (!first && (randnum.number(10) < 2)) {
-                        String val;
-                        int num;
-                        do {
-                            num = randnum.number(pwgen.SYMBOLS_STR.length());
-                            cha = pwgen.SYMBOLS_STR.toCharArray()[num];
-                            val = String.valueOf(cha);
-                        } while ((pwFlags & pwgen.AMBIGUOUS) > 0
-                                && pwgen.AMBIGUOUS_STR.contains(val));
-                        password += val;
-                        curSize++;
-
-                        featureFlags &= ~pwgen.SYMBOLS;
-                    }
-                }
-
-                // OK, figure out what the next element should be
-                if (shouldBe == CONSONANT) {
-                    shouldBe = VOWEL;
-                } else {
-                    if ((prev & VOWEL) > 0 || (flags & DIPTHONG) > 0
-                            || (randnum.number(10) > 3)) {
-                        shouldBe = CONSONANT;
-                    } else {
-                        shouldBe = VOWEL;
-                    }
-                }
-                prev = flags;
-                first = false;
-            }
-        } while ((featureFlags & (pwgen.UPPERS | pwgen.DIGITS | pwgen.SYMBOLS))
-                > 0);
-        return password;
-    }
-}
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/pw_rand.java b/app/src/main/java/com/zeapo/pwdstore/pwgen/pw_rand.java
deleted file mode 100644
index 9afd5e4a..00000000
--- a/app/src/main/java/com/zeapo/pwdstore/pwgen/pw_rand.java
+++ /dev/null
@@ -1,70 +0,0 @@
-package com.zeapo.pwdstore.pwgen;
-
-class pw_rand {
-
-    /**
-     * Generates a completely random password.
-     *
-     * @param size    length of password to generate
-     * @param pwFlags flag field where set bits indicate conditions the
-     *                generated password must meet
-     *                <table summary ="bits of flag field">
-     *                <tr><td>Bit</td><td>Condition</td></tr>
-     *                <tr><td>0</td><td>include at least one number</td></tr>
-     *                <tr><td>1</td><td>include at least one uppercase letter</td></tr>
-     *                <tr><td>2</td><td>include at least one symbol</td></tr>
-     *                <tr><td>3</td><td>don't include ambiguous characters</td></tr>
-     *                <tr><td>4</td><td>don't include vowels</td></tr>
-     *                </table>
-     * @return the generated password
-     */
-    public static String rand(int size, int pwFlags) {
-        String password;
-        char cha;
-        int i, featureFlags, num;
-        String val;
-
-        String bank = "";
-        if ((pwFlags & pwgen.DIGITS) > 0) {
-            bank += pwgen.DIGITS_STR;
-        }
-        if ((pwFlags & pwgen.UPPERS) > 0) {
-            bank += pwgen.UPPERS_STR;
-        }
-        bank += pwgen.LOWERS_STR;
-        if ((pwFlags & pwgen.SYMBOLS) > 0) {
-            bank += pwgen.SYMBOLS_STR;
-        }
-        do {
-            password = "";
-            featureFlags = pwFlags;
-            i = 0;
-            while (i < size) {
-                num = randnum.number(bank.length());
-                cha = bank.toCharArray()[num];
-                val = String.valueOf(cha);
-                if ((pwFlags & pwgen.AMBIGUOUS) > 0
-                        && pwgen.AMBIGUOUS_STR.contains(val)) {
-                    continue;
-                }
-                if ((pwFlags & pwgen.NO_VOWELS) > 0
-                        && pwgen.VOWELS_STR.contains(val)) {
-                    continue;
-                }
-                password += val;
-                i++;
-                if (pwgen.DIGITS_STR.contains(val)) {
-                    featureFlags &= ~pwgen.DIGITS;
-                }
-                if (pwgen.UPPERS_STR.contains(val)) {
-                    featureFlags &= ~pwgen.UPPERS;
-                }
-                if (pwgen.SYMBOLS_STR.contains(val)) {
-                    featureFlags &= ~pwgen.SYMBOLS;
-                }
-            }
-        } while ((featureFlags & (pwgen.UPPERS | pwgen.DIGITS | pwgen.SYMBOLS))
-                > 0);
-        return password;
-    }
-}
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/pwgen.java b/app/src/main/java/com/zeapo/pwdstore/pwgen/pwgen.java
deleted file mode 100644
index e08573f0..00000000
--- a/app/src/main/java/com/zeapo/pwdstore/pwgen/pwgen.java
+++ /dev/null
@@ -1,138 +0,0 @@
-package com.zeapo.pwdstore.pwgen;
-
-import android.content.Context;
-import android.content.SharedPreferences;
-
-import java.util.ArrayList;
-
-public class pwgen {
-    static final int DIGITS     = 0x0001;
-    static final int UPPERS     = 0x0002;
-    static final int SYMBOLS    = 0x0004;
-    static final int AMBIGUOUS  = 0x0008;
-    static final int NO_VOWELS  = 0x0010;
-
-    static final String DIGITS_STR = "0123456789";
-    static final String UPPERS_STR = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
-    static final String LOWERS_STR = "abcdefghijklmnopqrstuvwxyz";
-    static final String SYMBOLS_STR = "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~";
-    static final String AMBIGUOUS_STR = "B8G6I1l0OQDS5Z2";
-    static final String VOWELS_STR = "01aeiouyAEIOUY";
-
-    // No a, c, n, h, H, C, 1, N
-    private static final String pwOptions = "0ABsvy";
-
-    /**
-     * Sets password generation preferences.
-     *
-     * @param ctx     context from which to retrieve SharedPreferences from
-     *                preferences file 'pwgen'
-     * @param argv    options for password generation
-     *                <table summary="options for password generation">
-     *                <tr><td>Option</td><td>Description</td></tr>
-     *                <tr><td>0</td><td>don't include numbers</td></tr>
-     *                <tr><td>A</td><td>don't include uppercase letters</td></tr>
-     *                <tr><td>B</td><td>don't include ambiguous charactersl</td></tr>
-     *                <tr><td>s</td><td>generate completely random passwords</td></tr>
-     *                <tr><td>v</td><td>don't include vowels</td></tr>
-     *                <tr><td>y</td><td>include at least one symbol</td></tr>
-     *                </table>
-     * @param numArgv numerical options for password generation: length of
-     *                generated passwords followed by number of passwords to
-     *                generate
-     * @return <code>false</code> if a numerical options is invalid,
-     * <code>true</code> otherwise
-     */
-    public static boolean setPrefs(Context ctx, ArrayList<String> argv
-            , int... numArgv) {
-        SharedPreferences prefs
-                = ctx.getSharedPreferences("pwgen", Context.MODE_PRIVATE);
-        SharedPreferences.Editor editor = prefs.edit();
-
-        for (char option : pwOptions.toCharArray()) {
-            if (argv.contains(String.valueOf(option))) {
-                editor.putBoolean(String.valueOf(option), true);
-                argv.remove(String.valueOf(option));
-            } else {
-                editor.putBoolean(String.valueOf(option), false);
-            }
-        }
-        for (int i = 0; i < numArgv.length && i < 2; i++) {
-            if (numArgv[i] <= 0) {
-                // Invalid password length or number of passwords
-                return false;
-            }
-            String name = i == 0 ? "length" : "num";
-            editor.putInt(name, numArgv[i]);
-        }
-        editor.apply();
-        return true;
-    }
-
-    /**
-     * Generates passwords using the preferences set by
-     * {@link #setPrefs(Context, ArrayList, int...)}.
-     *
-     * @param ctx context from which to retrieve SharedPreferences from
-     *            preferences file 'pwgen'
-     * @return list of generated passwords
-     */
-    public static ArrayList<String> generate(Context ctx) {
-        SharedPreferences prefs
-                = ctx.getSharedPreferences("pwgen", Context.MODE_PRIVATE);
-
-        boolean phonemes = true;
-        int pwgenFlags = DIGITS | UPPERS;
-
-        for (char option : pwOptions.toCharArray()) {
-            if (prefs.getBoolean(String.valueOf(option), false)) {
-                switch(option) {
-                    case '0':
-                        pwgenFlags &= ~DIGITS;
-                        break;
-                    case 'A':
-                        pwgenFlags &= ~UPPERS;
-                        break;
-                    case 'B':
-                        pwgenFlags |= AMBIGUOUS;
-                        break;
-                    case 's':
-                        phonemes = false;
-                        // pwgenFlags = DIGITS | UPPERS;
-                        break;
-                    case 'y':
-                        pwgenFlags |= SYMBOLS;
-                        break;
-                    case 'v':
-                        phonemes = false;
-                        pwgenFlags |= NO_VOWELS; // | DIGITS | UPPERS;
-                        break;
-                }
-            }
-        }
-
-        int length = prefs.getInt("length", 8);
-        if (length < 5) {
-            phonemes = false;
-        }
-        if (length <= 2) {
-            pwgenFlags &= ~UPPERS;
-        }
-        if (length <= 1) {
-            pwgenFlags &= ~DIGITS;
-        }
-
-        ArrayList<String> passwords = new ArrayList<>();
-        int num = prefs.getInt("num", 1);
-        for (int i = 0; i < num; i++) {
-            if (phonemes) {
-                passwords.add(pw_phonemes.phonemes(length, pwgenFlags));
-            } else {
-                passwords.add(pw_rand.rand(length, pwgenFlags));
-            }
-        }
-        return passwords;
-    }
-
-}
-
diff --git a/app/src/main/java/com/zeapo/pwdstore/pwgen/randnum.java b/app/src/main/java/com/zeapo/pwdstore/pwgen/randnum.java
deleted file mode 100644
index 583d0863..00000000
--- a/app/src/main/java/com/zeapo/pwdstore/pwgen/randnum.java
+++ /dev/null
@@ -1,26 +0,0 @@
-package com.zeapo.pwdstore.pwgen;
-
-import java.security.NoSuchAlgorithmException;
-import java.security.SecureRandom;
-
-class randnum {
-    private static SecureRandom random;
-
-    static {
-        try {
-            random = SecureRandom.getInstance("SHA1PRNG");
-        } catch (NoSuchAlgorithmException e) {
-            throw new SecurityException("SHA1PRNG not available", e);
-        }
-    }
-
-    /**
-     * Generate a random number n, where 0 &lt;= n &lt; maxNum.
-     *
-     * @param maxNum the bound on the random number to be returned
-     * @return the generated random number
-     */
-    public static int number(int maxNum) {
-        return random.nextInt(maxNum);
-    }
-}