nCcAPFEy

1byte[] a = encryptFIN128AES("pls");
2String b = decryptFIN128AES(a);
3Log.e("AES_Test", "b = " + b);
4
5/**
6     * Encrypts a string with AES (128 bit key)
7     * @param fin
8     * @return the AES encrypted string
9     */
10    private byte[] encryptFIN128AES(String fin) {
11
12        SecretKeySpec sks = null;
13
14        try {
15            sks = new SecretKeySpec(generateKey(PASSPHRASE, SALT.getBytes(StandardCharsets.UTF_8)).getEncoded(), "AES");
16        } catch (Exception e) {
17            Log.e("encryptFIN128AES", "AES key generation error");
18        }
19
20        // Encode the original data with AES
21        byte[] encodedBytes = null;
22        try {
23            Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
24            c.init(Cipher.ENCRYPT_MODE, sks);
25            encodedBytes = c.doFinal(fin.getBytes(StandardCharsets.UTF_8));
26        } catch (Exception e) {
27            Log.e("encryptFIN128AES", "AES encryption error");
28        }
29
30        return encodedBytes;
31
32    }
33
34
35    /**
36     * Decrypts a string with AES (128 bit key)
37     * @param encodedBytes
38     * @return the decrypted String
39     */
40    private String decryptFIN128AES(byte[] encodedBytes) {
41
42        SecretKeySpec sks = null;
43
44        try {
45            sks = new SecretKeySpec(generateKey(PASSPHRASE, SALT.getBytes(StandardCharsets.UTF_8)).getEncoded(), "AES");
46        } catch (Exception e) {
47            Log.e("decryptFIN128AES", "AES key generation error");
48        }
49
50        // Decode the encoded data with AES
51        byte[] decodedBytes = null;
52        try {
53            Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
54            c.init(Cipher.DECRYPT_MODE, sks);
55            decodedBytes = c.doFinal(encodedBytes);
56        } catch (Exception e) {
57            Log.e("decryptFIN128AES", "AES decryption error");
58        }
59
60        //return Base64.encodeToString(decodedBytes, Base64.DEFAULT);
61        return new String(decodedBytes, StandardCharsets.UTF_8);
62    }
63
64
65/**
66     * Build private key from a passpharase/PIN (incl. key derivation (Uses PBKDF2))
67     * @param passphraseOrPin
68     * @param salt
69     * @return The generated SecretKey (Used for AES-encryption, key size specified in outputKeyLength)
70     */
71    public static SecretKey generateKey(char[] passphraseOrPin, byte[] salt)
72            throws NoSuchAlgorithmException, InvalidKeySpecException {
73        // Number of PBKDF2 hardening rounds to use. Larger values increase
74        // computation time. You should select a value that causes computation
75        // to take >100ms.
76        final int iterations = 1000;
77
78        // Generate a 256-bit key
79        final int outputKeyLength = 128;
80
81        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
82        KeySpec keySpec = new PBEKeySpec(passphraseOrPin, salt, iterations, outputKeyLength);
83        SecretKey secretKey = secretKeyFactory.generateSecret(keySpec);
84        return secretKey;
85    }
86	
87E/decryptFIN128AES: AES decryption error
88E/AndroidRuntime: FATAL EXCEPTION: Thread-176
89                  Process: testapp.ttyi.nfcapp, PID: 2920
90                  java.lang.NullPointerException: Attempt to get length of null array
91                      at java.lang.String.<init>(String.java:371)
92                      at testapp.ttyi.nfcapp.DisplayQRActivity.decryptFIN128AES(DisplayQRActivity.java:254)
93                      at testapp.ttyi.nfcapp.DisplayQRActivity.access$100(DisplayQRActivity.java:29)
94                      at testapp.ttyi.nfcapp.DisplayQRActivity$1.run(DisplayQRActivity.java:77)
95                      at java.lang.Thread.run(Thread.java:818)