Add support for new Authenticator Pro backup format

This adds support for Authenticator Pro's latest backup format changes.
The format of the content itself has not changed as far as I can tell, but
they do use a different cipher and KDF now: AES GCM and Argon2id,
respectively.

The memory cost is statically set at 64MiB. I suspect that this may
cause OOM situations on some lower-end devices, but we'll see, not much
we can do about that right now without making more changes.

app/src/main/java/com/beemdevelopment/aegis/importers/AuthenticatorProImporter.java

@@ -16,11 +16,13 @@
 import com.beemdevelopment.aegis.otp.SteamInfo;
 import com.beemdevelopment.aegis.otp.TotpInfo;
 import com.beemdevelopment.aegis.ui.dialogs.Dialogs;
+import com.beemdevelopment.aegis.ui.tasks.Argon2Task;
 import com.beemdevelopment.aegis.ui.tasks.PBKDFTask;
 import com.beemdevelopment.aegis.util.IOUtils;
 import com.beemdevelopment.aegis.vault.VaultEntry;
 import com.topjohnwu.superuser.io.SuFile;
 
+import org.bouncycastle.crypto.params.Argon2Parameters;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -44,9 +46,8 @@
 import javax.crypto.spec.IvParameterSpec;
 
 public class AuthenticatorProImporter extends DatabaseImporter {
-    private static final String HEADER = "AuthenticatorPro";
-    private static final int ITERATIONS = 64000;
-    private static final int KEY_SIZE = 32 * Byte.SIZE;
+    private static final String HEADER = "AUTHENTICATORPRO";
+    private static final String HEADER_LEGACY = "AuthenticatorPro";
     private static final String PKG_NAME = "me.jmh.authenticatorpro";
     private static final String PKG_DB_PATH = "files/proauth.db3";
 
@@ -90,24 +91,19 @@ private static State readExternal(InputStream stream) throws DatabaseImporterExc
         }
     }
 
-    private static EncryptedState readEncrypted(DataInputStream stream) throws DatabaseImporterException {
+    private static State readEncrypted(DataInputStream stream) throws DatabaseImporterException {
         try {
             byte[] headerBytes = new byte[HEADER.getBytes(StandardCharsets.UTF_8).length];
             stream.readFully(headerBytes);
             String header = new String(headerBytes, StandardCharsets.UTF_8);
-            if (!header.equals(HEADER)) {
-                throw new DatabaseImporterException("Invalid file header");
+            switch (header) {
+                case HEADER:
+                    return EncryptedState.parseHeader(stream);
+                case HEADER_LEGACY:
+                    return LegacyEncryptedState.parseHeader(stream);
+                default:
+                    throw new DatabaseImporterException("Invalid file header");
             }
-
-            int saltSize = 20;
-            byte[] salt = new byte[saltSize];
-            stream.readFully(salt);
-
-            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
-            int ivSize = cipher.getBlockSize();
-            byte[] iv = new byte[ivSize];
-            stream.readFully(iv);
-            return new EncryptedState(cipher, salt, iv, IOUtils.readAll(stream));
         } catch (UTFDataFormatException e) {
             throw new DatabaseImporterException("Invalid file header");
         } catch (IOException | NoSuchPaddingException | NoSuchAlgorithmException e) {
@@ -130,6 +126,13 @@ private static OtpInfo parseOtpInfo(int type, byte[] secret, Algorithm algo, int
     }
 
     static class EncryptedState extends State {
+        private static final int KEY_SIZE = 32;
+        private static final int MEMORY_COST = 16; // 2^16 KiB = 64 MiB
+        private static final int PARALLELISM = 4;
+        private static final int ITERATIONS = 3;
+        private static final int SALT_SIZE = 16;
+        private static final int IV_SIZE = 12;
+
         private final Cipher _cipher;
         private final byte[] _salt;
         private final byte[] _iv;
@@ -143,6 +146,81 @@ public EncryptedState(Cipher cipher, byte[] salt, byte[] iv, byte[] data) {
             _data = data;
         }
 
+        public JsonState decrypt(char[] password) throws DatabaseImporterException {
+            Argon2Task.Params params = getKeyDerivationParams(password);
+            SecretKey key = Argon2Task.deriveKey(params);
+            return decrypt(key);
+        }
+
+        public JsonState decrypt(SecretKey key) throws DatabaseImporterException {
+            try {
+                _cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(_iv));
+                byte[] decrypted = _cipher.doFinal(_data);
+                return new JsonState(new JSONObject(new String(decrypted, StandardCharsets.UTF_8)));
+            } catch (InvalidAlgorithmParameterException | IllegalBlockSizeException
+                     | JSONException | InvalidKeyException | BadPaddingException e) {
+                throw new DatabaseImporterException(e);
+            }
+        }
+
+        @Override
+        public void decrypt(Context context, DecryptListener listener) throws DatabaseImporterException {
+            Dialogs.showPasswordInputDialog(context, R.string.enter_password_aegis_title, 0, (Dialogs.TextInputListener) password -> {
+                Argon2Task.Params params = getKeyDerivationParams(password);
+                Argon2Task task = new Argon2Task(context, key -> {
+                    try {
+                        AuthenticatorProImporter.JsonState state = decrypt(key);
+                        listener.onStateDecrypted(state);
+                    } catch (DatabaseImporterException e) {
+                        listener.onError(e);
+                    }
+                });
+                Lifecycle lifecycle = ContextHelper.getLifecycle(context);
+                task.execute(lifecycle, params);
+            }, dialog -> listener.onCanceled());
+        }
+
+        private Argon2Task.Params getKeyDerivationParams(char[] password) {
+            Argon2Parameters argon2Params = new Argon2Parameters.Builder(Argon2Parameters.ARGON2_id)
+                    .withIterations(ITERATIONS)
+                    .withParallelism(PARALLELISM)
+                    .withMemoryPowOfTwo(MEMORY_COST)
+                    .withSalt(_salt)
+                    .build();
+            return new Argon2Task.Params(password, argon2Params, KEY_SIZE);
+        }
+
+        private static EncryptedState parseHeader(DataInputStream stream)
+            throws IOException, NoSuchPaddingException, NoSuchAlgorithmException {
+            byte[] salt = new byte[SALT_SIZE];
+            stream.readFully(salt);
+
+            byte[] iv = new byte[IV_SIZE];
+            stream.readFully(iv);
+
+            Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
+            return new EncryptedState(cipher, salt, iv, IOUtils.readAll(stream));
+        }
+    }
+
+    static class LegacyEncryptedState extends State {
+        private static final int ITERATIONS = 64000;
+        private static final int KEY_SIZE = 32 * Byte.SIZE;
+        private static final int SALT_SIZE = 20;
+
+        private final Cipher _cipher;
+        private final byte[] _salt;
+        private final byte[] _iv;
+        private final byte[] _data;
+
+        public LegacyEncryptedState(Cipher cipher, byte[] salt, byte[] iv, byte[] data) {
+            super(true);
+            _cipher = cipher;
+            _salt = salt;
+            _iv = iv;
+            _data = data;
+        }
+
         public JsonState decrypt(char[] password) throws DatabaseImporterException {
             PBKDFTask.Params params = getKeyDerivationParams(password);
             SecretKey key = PBKDFTask.deriveKey(params);
@@ -180,6 +258,18 @@ public void decrypt(Context context, DecryptListener listener) throws DatabaseIm
         private PBKDFTask.Params getKeyDerivationParams(char[] password) {
             return new PBKDFTask.Params("PBKDF2WithHmacSHA1", KEY_SIZE, password, _salt, ITERATIONS);
         }
+
+        private static LegacyEncryptedState parseHeader(DataInputStream stream)
+            throws IOException, NoSuchPaddingException, NoSuchAlgorithmException {
+            byte[] salt = new byte[SALT_SIZE];
+            stream.readFully(salt);
+
+            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+            int ivSize = cipher.getBlockSize();
+            byte[] iv = new byte[ivSize];
+            stream.readFully(iv);
+            return new LegacyEncryptedState(cipher, salt, iv, IOUtils.readAll(stream));
+        }
     }
 
     private static class JsonState extends State {

app/src/main/java/com/beemdevelopment/aegis/ui/tasks/Argon2Task.java

@@ -0,0 +1,71 @@
+package com.beemdevelopment.aegis.ui.tasks;
+
+import android.content.Context;
+
+import com.beemdevelopment.aegis.R;
+
+import org.bouncycastle.crypto.generators.Argon2BytesGenerator;
+import org.bouncycastle.crypto.params.Argon2Parameters;
+
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+
+public class Argon2Task extends ProgressDialogTask<Argon2Task.Params, SecretKey> {
+    private final Callback _cb;
+
+    public Argon2Task(Context context, Callback cb) {
+        super(context, context.getString(R.string.unlocking_vault));
+        _cb = cb;
+    }
+
+    @Override
+    protected SecretKey doInBackground(Params... args) {
+        setPriority();
+
+        Params params = args[0];
+        return deriveKey(params);
+    }
+
+    public static SecretKey deriveKey(Params params) {
+        Argon2BytesGenerator gen = new Argon2BytesGenerator();
+        gen.init(params.getArgon2Params());
+
+        byte[] key = new byte[params.getKeySize()];
+        gen.generateBytes(params.getPassword(), key);
+        return new SecretKeySpec(key, 0, key.length, "AES");
+    }
+
+    @Override
+    protected void onPostExecute(SecretKey key) {
+        super.onPostExecute(key);
+        _cb.onTaskFinished(key);
+    }
+
+    public interface Callback {
+        void onTaskFinished(SecretKey key);
+    }
+
+    public static class Params {
+        private final char[] _password;
+        private final Argon2Parameters _argon2Params;
+        private final int _keySize;
+
+        public Params(char[] password, Argon2Parameters argon2Params, int keySize) {
+            _password = password;
+            _argon2Params = argon2Params;
+            _keySize = keySize;
+        }
+
+        public char[] getPassword() {
+            return _password;
+        }
+
+        public Argon2Parameters getArgon2Params() {
+            return _argon2Params;
+        }
+
+        public int getKeySize() {
+            return _keySize;
+        }
+    }
+}

app/src/test/java/com/beemdevelopment/aegis/importers/DatabaseImporterTest.java

@@ -146,11 +146,16 @@ public void testImportTotpAuthenticatorInternal() throws IOException, DatabaseIm
     public void testImportAuthProEncrypted() throws DatabaseImporterException, IOException, OtpInfoException {
         List<VaultEntry> entries = importEncrypted(AuthenticatorProImporter.class, "authpro_encrypted.bin", state -> {
             char[] password = "test".toCharArray();
-            try {
-                return ((AuthenticatorProImporter.EncryptedState) state).decrypt(password);
-            } catch (DatabaseImporterException e) {
-                throw new DatabaseImporterException(e);
-            }
+            return ((AuthenticatorProImporter.EncryptedState) state).decrypt(password);
+        });
+        checkImportedEntries(entries);
+    }
+
+    @Test
+    public void testImportAuthProEncryptedLegacy() throws DatabaseImporterException, IOException, OtpInfoException {
+        List<VaultEntry> entries = importEncrypted(AuthenticatorProImporter.class, "authpro_encrypted_legacy.bin", state -> {
+            char[] password = "test".toCharArray();
+            return ((AuthenticatorProImporter.LegacyEncryptedState) state).decrypt(password);
         });
         checkImportedEntries(entries);
     }