I am trying to learn AES by testing my code against https://aesencryption.net. I previously had an error in Base64.encodeBase64String
and also Base64.decodeBase64 // encode/decode Base64
. So I manipulated Base64 somehow to resolve the error. Now in my app the text is encrypted and decrypted properly, I think. But when I try to encrypt or decrypt the same text server-side (at aesencryption.net), the site is not able to decrypt my encrypted string. Please help.
Following is my code :
public class MainActivity extends AppCompatActivity { static final String TAG = "SymmetricAlgorithmAES"; private static SecretKeySpec secretKey ; private static byte[] key ; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Original text // {"type":"Success","httpCode":"200","code":"200","message":{"pin":"11111"},"extra":""} String theTestText = "hi"; TextView tvorig = (TextView)findViewById(R.id.tvorig); tvorig.setText("n[ORIGINAL]:n" + theTestText + "n"); final String strPssword = "android"; setKey(strPssword); // Encode the original data with AES byte[] encodedBytes = null; try { Cipher c = Cipher.getInstance("AES"); c.init(Cipher.ENCRYPT_MODE,secretKey); encodedBytes = c.doFinal(theTestText.getBytes()); } catch (Exception e) { Log.e(TAG, "AES encryption error"); } TextView tvencoded = (TextView)findViewById(R.id.tvencoded); tvencoded.setText("[ENCODED]:n" + Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "n"); Log.d(TAG, Base64.encodeToString(encodedBytes, Base64.DEFAULT)); // Decode the encoded data with AES byte[] decodedBytes = null; try { Cipher c = Cipher.getInstance("AES"); c.init(Cipher.DECRYPT_MODE, secretKey); decodedBytes = c.doFinal(encodedBytes); } catch (Exception e) { Log.e(TAG, "AES decryption error"); } TextView tvdecoded = (TextView)findViewById(R.id.tvdecoded); tvdecoded.setText("[DECODED]:n" + new String(decodedBytes) + "n"); } public static void setKey(String myKey){ MessageDigest sha = null; try { key = myKey.getBytes("UTF-8"); System.out.println(key.length); sha = MessageDigest.getInstance("SHA-1"); key = sha.digest(key); key = Arrays.copyOf(key, 16); // use only first 128 bit System.out.println(key.length); System.out.println(new String(key,"UTF-8")); secretKey = new SecretKeySpec(key, "AES"); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } }
Thanks in advance.
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Answer
I do something like this which actually works 😉
public class AESCrypter { private final Cipher cipher; private final SecretKeySpec key; private AlgorithmParameterSpec spec; public AESCrypter(String password) throws Exception { // hash password with SHA-256 and crop the output to 128-bit for key MessageDigest digest = MessageDigest.getInstance("SHA-256"); digest.update(password.getBytes("UTF-8")); byte[] keyBytes = new byte[32]; System.arraycopy(digest.digest(), 0, keyBytes, 0, keyBytes.length); cipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); key = new SecretKeySpec(keyBytes, "AES"); spec = getIV(); } public AlgorithmParameterSpec getIV() { byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }; IvParameterSpec ivParameterSpec; ivParameterSpec = new IvParameterSpec(iv); return ivParameterSpec; } public String encrypt(String plainText) throws Exception { cipher.init(Cipher.ENCRYPT_MODE, key, spec); byte[] encrypted = cipher.doFinal(plainText.getBytes("UTF-8")); String encryptedText = new String(Base64.encode(encrypted, Base64.DEFAULT), "UTF-8"); return encryptedText; } public String decrypt(String cryptedText) throws Exception { cipher.init(Cipher.DECRYPT_MODE, key, spec); byte[] bytes = Base64.decode(cryptedText, Base64.DEFAULT); byte[] decrypted = cipher.doFinal(bytes); String decryptedText = new String(decrypted, "UTF-8"); return decryptedText; } }
Call this class like this :
try { AESCrypter _crypt = new AESCrypter("password"); String output = ""; String plainText = "top secret message"; output = _crypt.encrypt(plainText); //encrypt System.out.println("encrypted text=" + output); output = _crypt.decrypt(output); //decrypt System.out.println("decrypted text=" + output); } catch (Exception e) { e.printStackTrace(); }
And for iPhone (Code is here) : https://github.com/Gurpartap/AESCrypt-ObjC
Hope this code works for you too 🙂