diff --git a/app/build.gradle b/app/build.gradle
index f3c052d..3bbdc1a 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -8,7 +8,7 @@ android {
 
     defaultConfig {
         applicationId "com.example.bsm_fingerptint_tutorial"
-        minSdk 24
+        minSdk 26
         targetSdk 33
         versionCode 1
         versionName "1.0"
diff --git a/app/src/main/java/com/example/bsm_fingerptint_tutorial/MainActivity.java b/app/src/main/java/com/example/bsm_fingerptint_tutorial/MainActivity.java
index 63402c3..ec34fbb 100644
--- a/app/src/main/java/com/example/bsm_fingerptint_tutorial/MainActivity.java
+++ b/app/src/main/java/com/example/bsm_fingerptint_tutorial/MainActivity.java
@@ -71,18 +71,6 @@ public class MainActivity extends AppCompatActivity {
                 public void onAuthenticationSucceeded(@NonNull BiometricPrompt.AuthenticationResult result) {
                     super.onAuthenticationSucceeded(result);
 
-                    String plaintext = "Tekst do zaszyforwania";
-                    byte[] encryptedInfo;
-
-                    try {
-                        encryptedInfo = result.getCryptoObject().getCipher().doFinal(
-                                plaintext.getBytes(Charset.defaultCharset()));
-                    } catch (GeneralSecurityException e) {
-                        throw new RuntimeException(e);
-                    }
-
-                    Log.d("MY_LOGS", "Success! Encrypted txt: " + Arrays.toString(encryptedInfo));
-
                     Toast.makeText(getApplicationContext(),"Authentication succeeded!", Toast.LENGTH_SHORT).show();
 
                     Intent intent = new Intent(getApplicationContext(), NotepadActivity.class);
@@ -104,54 +92,13 @@ public class MainActivity extends AppCompatActivity {
                 .setAllowedAuthenticators(BiometricManager.Authenticators.BIOMETRIC_STRONG)
                 .build();
 
-
-        try {
-            generateSecretKey(new KeyGenParameterSpec.Builder(KEY_NAME, KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
-                    .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
-                    .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
-                    .setUserAuthenticationRequired(true)
-                    .setInvalidatedByBiometricEnrollment(true)
-                    .build()
-                    );
-        } catch (GeneralSecurityException e) {
-            throw new RuntimeException(e);
-        }
-
-
         btnLogIn.setOnClickListener(view -> {
-            try {
-                Cipher cipher = getCipher();
-                SecretKey secretKey = getSecretKey();
-                cipher.init(Cipher.ENCRYPT_MODE, secretKey);
-                biometricPrompt.authenticate(promptInfo, new BiometricPrompt.CryptoObject(cipher));
-            } catch (GeneralSecurityException | IOException e) {
-                throw new RuntimeException(e);
-            }
+                biometricPrompt.authenticate(promptInfo);
+
         });
 
     }
 
-
-
-    private void generateSecretKey(KeyGenParameterSpec keyGenParameterSpec) throws GeneralSecurityException {
-        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES", "AndroidKeyStore");
-        keyGenerator.init(keyGenParameterSpec);
-        keyGenerator.generateKey();
-    }
-
-    private SecretKey getSecretKey() throws GeneralSecurityException, IOException {
-        KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
-
-        keyStore.load(null);
-        return ((SecretKey)keyStore.getKey(KEY_NAME, null));
-    }
-
-    private Cipher getCipher() throws GeneralSecurityException{
-        return Cipher.getInstance("AES/CBC/PKCS7Padding");
-        //KeyProperties.KEY_ALGORITHM_AES + "/" + KeyProperties.BLOCK_MODE_CBC + "/" + KeyProperties.ENCRYPTION_PADDING_PKCS7
-    }
-
-
 }
 
 
diff --git a/app/src/main/java/com/example/bsm_fingerptint_tutorial/NotepadActivity.java b/app/src/main/java/com/example/bsm_fingerptint_tutorial/NotepadActivity.java
index 9e91494..c61ecfd 100644
--- a/app/src/main/java/com/example/bsm_fingerptint_tutorial/NotepadActivity.java
+++ b/app/src/main/java/com/example/bsm_fingerptint_tutorial/NotepadActivity.java
@@ -2,12 +2,15 @@ package com.example.bsm_fingerptint_tutorial;
 
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.biometric.BiometricPrompt;
 import androidx.lifecycle.LifecycleCoroutineScope;
 
 import android.annotation.SuppressLint;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.os.Bundle;
+import android.security.keystore.KeyGenParameterSpec;
+import android.security.keystore.KeyProperties;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -17,16 +20,31 @@ import android.widget.LinearLayout;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import java.io.IOException;
+import java.nio.charset.Charset;
 import java.security.GeneralSecurityException;
+import java.security.KeyStore;
+import java.security.SecureRandom;
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Base64;
 import java.util.List;
 
+import javax.crypto.Cipher;
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.IvParameterSpec;
+
 public class NotepadActivity extends AppCompatActivity {
 
     private List<Note> noteList;
     private LinearLayout notesContainer;
     private static final String SHARED_NAME_NOTES = "Notatki";
 
+    private static final String KEY_NAME = "nazwaKluczaa";
+
+
+
     Button buttonLogout, buttonAddNote;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -36,7 +54,11 @@ public class NotepadActivity extends AppCompatActivity {
         noteList = new ArrayList<>();
         notesContainer = findViewById(R.id.notes_container);
 
-        loadNotesFromPreferencesToList();
+        try {
+            loadNotesFromPreferencesToList();
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
         displayNotes();
 
         buttonLogout = findViewById(R.id.btn_logout);
@@ -75,7 +97,13 @@ public class NotepadActivity extends AppCompatActivity {
 
                 noteList.add(note);
 
-                saveNotesToPreferences("add");
+                try {
+                    saveNotesToPreferences("add");
+                } catch (GeneralSecurityException e) {
+                    throw new RuntimeException(e);
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
 
                 createNoteView(note);
                 Toast.makeText(NotepadActivity.this, "Note saved!", Toast.LENGTH_SHORT).show();
@@ -116,7 +144,13 @@ public class NotepadActivity extends AppCompatActivity {
                 noteList.add(note);
                 createNoteView(note);
 
-                saveNotesToPreferences("add");
+                try {
+                    saveNotesToPreferences("add");
+                } catch (GeneralSecurityException e) {
+                    throw new RuntimeException(e);
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
 
             }else {
                 Toast.makeText(NotepadActivity.this, "Enter title and content!", Toast.LENGTH_SHORT).show();
@@ -130,44 +164,92 @@ public class NotepadActivity extends AppCompatActivity {
         alertDialog.show();
     }
 
-    private void saveNotesToPreferences(String mode){
+    private void saveNotesToPreferences(String mode) throws GeneralSecurityException, IOException {
         SharedPreferences sharedPreferences = getSharedPreferences(SHARED_NAME_NOTES, MODE_PRIVATE);
         SharedPreferences.Editor editor = sharedPreferences.edit();
 
-        if (mode.equals("del")){
-            int noteCount = sharedPreferences.getInt("_notecount_", 0);
-            for(int i=0; i<noteCount; i++){
-                editor.remove(i + "_title_");
-                editor.remove(i + "_content_");
+
+            if (mode.equals("del")){
+                int noteCount = sharedPreferences.getInt("_notecount_", 0);
+                for(int i=0; i<noteCount; i++){
+                    editor.remove(i + "_title_");
+                    editor.remove(i + "_content_");
+                }
             }
-        }
 
-        editor.putInt("_notecount_", noteList.size());
-        for(int i=0; i<noteList.size(); i++){
-            Note note = noteList.get(i);
-            editor.putString(i + "_title_", note.getTitle());
-            editor.putString(i + "_content_", note.getContent());
-        }
+            IvParameterSpec iv = UtilsCipher.generateIv();
+            String ivString = ivToString(iv);
+            saveIvStringToShared(ivString);
+
+            SecretKey secretKey = UtilsCipher.generateRandomKey(KEY_NAME);
+
+
+            editor.putInt("_notecount_", noteList.size());
+            for(int i=0; i<noteList.size(); i++){
+                Note note = noteList.get(i);
+
+                String encryptedTitle = UtilsCipher.encrypt("AES/CBC/PKCS7Padding", note.getTitle(), secretKey, iv);
+                String encryptedContent = UtilsCipher.encrypt("AES/CBC/PKCS7Padding", note.getContent(), secretKey, iv);
+
+                editor.putString(i + "_title_", encryptedTitle);
+                editor.putString(i + "_content_", encryptedContent);
+            }
+
+            editor.apply();
+
 
-        editor.apply();
     }
 
-    private void loadNotesFromPreferencesToList(){
+    private void loadNotesFromPreferencesToList() throws Exception {
         SharedPreferences sharedPreferences = getSharedPreferences(SHARED_NAME_NOTES, MODE_PRIVATE);
         int noteCount = sharedPreferences.getInt("_notecount_", 0);
 
+        String ivString = getIVStringFromShared();
+        IvParameterSpec iv = stringToIv(ivString);
+
+        SecretKey secretKey = UtilsCipher.retrieveKey(KEY_NAME);
+
+
         for(int i=0; i<noteCount; i++){
             String title = sharedPreferences.getString(i + "_title_", "");
             String content = sharedPreferences.getString(i + "_content_", "");
 
+            String decryptedTitle = UtilsCipher.decrypt("AES/CBC/PKCS7Padding", title, secretKey, iv);
+            String decryptedContent = UtilsCipher.decrypt("AES/CBC/PKCS7Padding", content, secretKey, iv);
+
             Note note = new Note();
-            note.setTitle(title);
-            note.setContent(content);
+            note.setTitle(decryptedTitle);
+            note.setContent(decryptedContent);
 
             noteList.add(note);
         }
     }
 
+    private void saveIvStringToShared(String ivString){
+        SharedPreferences sharedPreferences = getSharedPreferences(SHARED_NAME_NOTES, MODE_PRIVATE);
+        SharedPreferences.Editor editor = sharedPreferences.edit();
+
+        editor.putString("_iv_", ivString);
+        editor.apply();
+    }
+
+    private String getIVStringFromShared(){
+        SharedPreferences sharedPreferences = getSharedPreferences(SHARED_NAME_NOTES, MODE_PRIVATE);
+        return sharedPreferences.getString("_iv_", "err");
+    }
+
+    private static IvParameterSpec stringToIv(String ivString) {
+        byte[] ivBytes = Base64.getDecoder().decode(ivString);
+        return new IvParameterSpec(ivBytes);
+    }
+
+    private static String ivToString(IvParameterSpec ivParameterSpec) {
+        byte[] ivBytes = ivParameterSpec.getIV();
+        return Base64.getEncoder().encodeToString(ivBytes);
+    }
+
+
+
     private void createNoteView(final Note note){
         @SuppressLint("InflateParams") View noteView = getLayoutInflater().inflate(R.layout.note_item, null);
         TextView noteTitleTextView = noteView.findViewById(R.id.note_title_text_view);
@@ -200,7 +282,13 @@ public class NotepadActivity extends AppCompatActivity {
 
     private void deleteNoteAndRefresh(Note note){
         noteList.remove(note);
-        saveNotesToPreferences("del");
+        try {
+            saveNotesToPreferences("del");
+        } catch (GeneralSecurityException e) {
+            throw new RuntimeException(e);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
         refreshNotesView();
     }
 
diff --git a/app/src/main/java/com/example/bsm_fingerptint_tutorial/UtilsCipher.java b/app/src/main/java/com/example/bsm_fingerptint_tutorial/UtilsCipher.java
new file mode 100644
index 0000000..8dd40f3
--- /dev/null
+++ b/app/src/main/java/com/example/bsm_fingerptint_tutorial/UtilsCipher.java
@@ -0,0 +1,91 @@
+package com.example.bsm_fingerptint_tutorial;
+
+import android.security.keystore.KeyGenParameterSpec;
+import android.security.keystore.KeyProperties;
+import android.util.Log;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.security.GeneralSecurityException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.Key;
+import java.security.KeyStore;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.security.SecureRandom;
+import java.util.Base64;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.KeyGenerator;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+public class UtilsCipher {
+
+    public static SecretKey generateRandomKey(String keyAlias) throws NoSuchProviderException,
+            NoSuchAlgorithmException {
+
+        try {
+            KeyGenerator keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
+            KeyGenParameterSpec keyGenParameterSpec = new KeyGenParameterSpec.Builder(
+                    keyAlias,
+                    KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
+                    .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
+                    .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
+                    .setRandomizedEncryptionRequired(false)
+                    .build();
+
+            keyGenerator.init(keyGenParameterSpec);
+            Log.i("KEY_GENERATEOT", keyGenerator.generateKey().toString());
+            return keyGenerator.generateKey();
+        } catch (Exception e) {
+            e.printStackTrace();
+            return null;
+        }
+
+
+    }
+
+    public static SecretKey retrieveKey(String keyAlias) throws Exception {
+        KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
+        keyStore.load(null);
+
+        KeyStore.SecretKeyEntry secretKeyEntry = (KeyStore.SecretKeyEntry) keyStore.getEntry(keyAlias, null);
+        return secretKeyEntry.getSecretKey();
+    }
+
+    public static String encrypt(String algorithm, String input, SecretKey key, IvParameterSpec iv) throws
+            NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException,
+            BadPaddingException, IllegalBlockSizeException {
+
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.ENCRYPT_MODE, key, iv);
+        byte[] cipherText = cipher.doFinal(input.getBytes());
+        return Base64.getEncoder().encodeToString(cipherText);
+    }
+
+    public static String decrypt(String algorithm, String cipherText, SecretKey key, IvParameterSpec iv) throws NoSuchPaddingException, NoSuchAlgorithmException,
+            InvalidAlgorithmParameterException, InvalidKeyException,
+            BadPaddingException, IllegalBlockSizeException{
+
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.DECRYPT_MODE, key, iv);
+        byte[] plainText = cipher.doFinal(Base64.getDecoder().decode(cipherText));
+        return new String(plainText);
+    }
+
+    public static IvParameterSpec generateIv(){
+        byte[] iv = new byte[16];
+        new SecureRandom().nextBytes(iv);
+        return new IvParameterSpec(iv);
+    }
+
+
+
+
+}