AES keys different in Arduino and Android implementation

Question

I am trying to send a password from Android to Arduino using AES Algo. I am facing issues with the generated key difference in both encrypted implementations. I am sure there is some configuration sync. I searched internet found some strings and tried all. But still my keys/cipher doesn't match.

Any inputs are welcomed .

Arduino code:

void setup()
{
Serial.begin(57600);

}

void loop()
{
  int i = 0;
uint8_t key[] = {0,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6};
char data[] = "sanmacs88       "; //16 chars == 16 bytes
aes128_enc_single(key, data);
Serial.println("encrypted:");
for(i=0;i<16;i++)
Serial.println((int)data[i]);
aes128_dec_single(key, data);
Serial.println("decrypted:");
Serial.println(data);
delay(10000);
  }

Output : 75 45 -7 78 89 123 1 96 -10 36 110 -105 -119 -11 -7 -8 decrypted: sanmacs88

Java Code :

public class AES {
  static String IV = "AAAAAAAAAAAAAAAA";
  static String plaintext = "sanmacs88       "; /*Note null padding*/
  static String encryptionKey = "0123456789123456";
  public static void main(String [] args) {
    try {

      System.out.println("==Java==");
      System.out.println("plain:   " + plaintext);

      byte[] cipher = encrypt(plaintext, encryptionKey);

      System.out.print("cipher:  ");
      for (int i=0; i<cipher.length; i++)
        System.out.print(new Integer(cipher[i])+" ");
      System.out.println("");

      String decrypted = decrypt(cipher, encryptionKey);

      System.out.println("decrypt: " + decrypted);

    } catch (Exception e) {
      e.printStackTrace();
    } 
  }

  public static byte[] encrypt(String plainText, String encryptionKey) throws Exception {
    Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding", "SunJCE");
    SecretKeySpec key = new SecretKeySpec(encryptionKey.getBytes("UTF-8"), "AES");
    cipher.init(Cipher.ENCRYPT_MODE, key);
    return cipher.doFinal(plainText.getBytes("UTF-8"));
  }

  public static String decrypt(byte[] cipherText, String encryptionKey) throws Exception{
    Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding", "SunJCE");
    SecretKeySpec key = new SecretKeySpec(encryptionKey.getBytes("UTF-8"), "AES");
    cipher.init(Cipher.DECRYPT_MODE, key);
    return new String(cipher.doFinal(cipherText),"UTF-8");
  }
}

Output:

plain:   sanmacs88       
cipher:  38 60 69 -111 -44 115 -84 -118 72 -124 86 69 -61 87 -20 63 
decrypt: sanmacs88

When displaying binary data it is customery and more easily understood in hexadecimal format. — zaph
– zaph, Commented Jul 12, 2016 at 18:24

zaph · Accepted Answer · 2016-07-13 16:34:06Z

1

The Java key is specified by a string, the Arduino key by an integer array.

The Java key : static String encryptionKey = "0123456789123456";
In hex: 30313233 34353637 38393132 33343536

The Arduino key: uint8_t key[] = {0,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6};
In hex: 00010203 04050607 08090102 03040506 <— does not match the Java key

Change the Arduino key to: uint8_t key[] = {"0123456789123456"];
or: uint8_t key[] = {'0','1','2','3','4','5','6','7','8','9','1','2','3','4','5','6'};

edited Jul 13, 2016 at 16:34

answered Jul 12, 2016 at 18:45

zaph

113k21 gold badges196 silver badges234 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

gueverra Over a year ago

Sorry for that , I copied it wrong.It was 16 bytes. My question is how i can sync? both of them to result in same cipher.

gueverra Over a year ago

Yes it worked , thanks a ton !! Much appreciated . Sorry for being late. Just tested.

Collectives™ on Stack Overflow

AES keys different in Arduino and Android implementation

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related