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1//Enkrypcja i Dekrypcja mojego autorstwa
2
3package com.example.notesh;
4
5
6import android.content.Context;
7import android.content.SharedPreferences;
8import android.os.Build;
9import android.security.keystore.KeyGenParameterSpec;
10import android.security.keystore.KeyProperties;
11import android.util.Base64;
12
13import androidx.annotation.RequiresApi;
14
15import java.io.IOException;
16import java.security.InvalidAlgorithmParameterException;
17import java.security.KeyStore;
18import java.security.KeyStoreException;
19import java.security.NoSuchAlgorithmException;
20import java.security.NoSuchProviderException;
21import java.security.UnrecoverableKeyException;
22import java.security.cert.CertificateException;
23
24import javax.crypto.Cipher;
25import javax.crypto.KeyGenerator;
26import javax.crypto.NoSuchPaddingException;
27import javax.crypto.SecretKey;
28import javax.crypto.spec.IvParameterSpec;
29
30
31public class SecretKeyUtils {
32
33    @RequiresApi(api = Build.VERSION_CODES.M)
34    public static void CheckAndGeneratePassword()
35    {
36        try {
37            SecretKey key = getSecretKey();
38            if (key == null)
39            {
40                generateSecretKey(new KeyGenParameterSpec.Builder(
41                        "NoteHSecretKey",
42                        KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
43                        .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
44                        .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
45                        .build());
46            }
47        } catch (Exception e)
48        {
49            System.out.println("CheckAndGeneratePassword: " + e.toString());
50        }
51    }
52
53
54
55    @RequiresApi(api = Build.VERSION_CODES.M)
56    public static void generateSecretKey(KeyGenParameterSpec keyGenParameterSpec) throws NoSuchProviderException, NoSuchAlgorithmException, InvalidAlgorithmParameterException {
57        KeyGenerator keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
58        keyGenerator.init(keyGenParameterSpec);
59        keyGenerator.generateKey();
60    }
61
62    public static SecretKey getSecretKey() throws KeyStoreException, CertificateException, NoSuchAlgorithmException, IOException, UnrecoverableKeyException {
63        KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
64
65        // Before the keystore can be accessed, it must be loaded.
66        keyStore.load(null);
67        return ((SecretKey)keyStore.getKey("NoteHSecretKey", null));
68    }
69
70    public static Cipher getCipher() throws NoSuchPaddingException, NoSuchAlgorithmException {
71        return Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"
72                + KeyProperties.BLOCK_MODE_CBC + "/"
73                + KeyProperties.ENCRYPTION_PADDING_PKCS7);
74    }
75
76    public static String encryptNote(String note, Context context)
77    {
78        try {
79
80
81            Cipher cipher = getCipher();
82            SecretKey secretKey = getSecretKey();
83            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
84
85            byte[] iv = cipher.getIV();
86
87            SharedPreferences sharedPref = context.getSharedPreferences("szyfr", Context.MODE_PRIVATE);
88            SharedPreferences.Editor editor = sharedPref.edit();
89
90            editor.putString("ivi", Base64.encodeToString(iv, Base64.DEFAULT));
91            editor.commit();
92
93            byte[] encryptedInfo = cipher.doFinal(note.getBytes("UTF-8"));
94
95            return Base64.encodeToString(encryptedInfo, Base64.NO_WRAP);
96        }catch (Exception e)
97        {
98            System.out.println("Error while encrypting: " + e.toString());
99        }
100
101        return "";
102    }
103
104    public static String decryptNote(String note, Context context)
105    {
106        try {
107
108            SharedPreferences sharedPref = context.getSharedPreferences("note",Context.MODE_PRIVATE);
109            String ivArray = sharedPref.getString("ivi","");
110            byte[] iv = Base64.decode(ivArray, Base64.DEFAULT);
111
112            Cipher cipher = getCipher();
113            SecretKey secretKey = getSecretKey();
114            cipher.init(Cipher.DECRYPT_MODE, secretKey,new IvParameterSpec(iv));
115            return new String(cipher.doFinal(Base64.decode(note,Base64.NO_WRAP)));
116        }catch (Exception e)
117        {
118            System.out.println("Error while encrypting: " + e.toString());
119        }
120
121        return "";
122    }
123
124
125