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1 public byte[] doEncrypt(String key, byte[] plaintext,byte[] aad) {
2
3        SecureRandom secureRandom = new SecureRandom();
4
5        try {
6            byte [] iv = new byte[IV_LENGTH_BIT];
7            secureRandom.nextBytes(iv);
8
9            SecretKey secretKey=generateSecretKey(key,iv);
10
11            Cipher cipher = Cipher.getInstance(ALGORITHM);
12            cipher.init(Cipher.ENCRYPT_MODE, secretKey, new GCMParameterSpec(TAG_LENGTH_BIT, iv));
13
14            cipher.updateAAD(aad);
15
16            byte[] encrypted = cipher.doFinal(plaintext);
17
18            ByteBuffer byteBuffer = ByteBuffer.allocate(4 + iv.length + encrypted.length);
19            Log.d(TAG,"ENd_iv="+iv.length);
20            byteBuffer.putInt(iv.length);
21            byteBuffer.put(iv);
22            byteBuffer.put(encrypted);
23            Log.d(TAG, byteBuffer.toString());
24            return byteBuffer.array();
25
26        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | BadPaddingException | IllegalBlockSizeException | InvalidAlgorithmParameterException | InvalidKeySpecException e) {
27            throw new RuntimeException(e);
28        }
29    }
30
31
32    public static byte[] doDecrypt(String key, String enc_data,byte[] aad) {
33
34        try {
35            byte[] encypt_data=Base64.decode(enc_data,Base64.DEFAULT);
36            ByteBuffer byteBuffer = ByteBuffer.wrap(encypt_data);
37            int ivLength = byteBuffer.getInt();
38            Log.d(TAG,"IV len="+ivLength);
39            if(ivLength < 12 || ivLength >= 16) { // check input parameter
40                throw new IllegalArgumentException("Invalid iv length");
41            }
42            byte[] iv = new byte[ivLength];
43            byteBuffer.get(iv);
44
45            byte[] encrypted = new byte[byteBuffer.remaining()];
46            byteBuffer.get(encrypted);
47            SecretKey secretKey=generateSecretKey(key,iv);
48            Cipher cipher = Cipher.getInstance(ALGORITHM);
49            cipher.init(Cipher.DECRYPT_MODE, secretKey, new GCMParameterSpec(TAG_LENGTH_BIT, iv));
50            cipher.updateAAD(aad);
51
52            Log.d(TAG,"data="+enc_data);
53            return cipher.doFinal(encypt_data);
54
55
56        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | InvalidAlgorithmParameterException | BadPaddingException | IllegalBlockSizeException | InvalidKeySpecException e) {
57             throw new RuntimeException(e);
58        }
59    }