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I'm looking for an analogous set of encryption functions in Objective C for IOS to integrate with my PHP web service.

Here are the PHP encryption functions:

public function encrypt($input, $key) {
    $size = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_ECB);
    $input = self::pkcs5_pad($input, $size);
    $td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_ECB, '');
    $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
    mcrypt_generic_init($td, $key, $iv);
    $data = mcrypt_generic($td, $input);
    mcrypt_generic_deinit($td);
    mcrypt_module_close($td);
    $data = base64_encode($data);
    return $data;
}

private function pkcs5_pad ($text, $blocksize) {
    $pad = $blocksize - (strlen($text) % $blocksize);
    return $text . str_repeat(chr($pad), $pad);
}

public function decrypt($sStr, $sKey) {
    $decrypted= mcrypt_decrypt(
    MCRYPT_RIJNDAEL_128,
    $sKey,
    base64_decode($sStr),
    MCRYPT_MODE_ECB
    );
    $dec_s = strlen($decrypted);
    $padding = ord($decrypted[$dec_s-1]);
    $decrypted = substr($decrypted, 0, -$padding);
    return $decrypted;
}

Here are the android / JAVA functions that match it:

public static String encrypt(String input, String key){
    byte[] crypted = null;
    try{
        SecretKeySpec skey = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, skey);
        crypted = cipher.doFinal(input.getBytes());
    } catch(Exception e) {
        //Log.e("ERR", e.toString());
    }
    return new String(Base64.encode(crypted, Base64.DEFAULT));
}

public static String decrypt(String input, String key){
    byte[] output = null;
    try{
        SecretKeySpec skey = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, skey);
        output = cipher.doFinal(Base64.decode(input, Base64.DEFAULT));
    } catch(Exception e) {
    //Log.e("ERR", e.toString());
    }
    return new String(output);
}

What would the matching functions be for IOS / objective C so that no changes would need to be made to the backend PHP to match up properly? Thanks!!!

Phyllis Sutherland
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    What's your threat assessment? Someone stealing/mangling the data on the device, or someone stealing stealing/mangling the data while it's on the wire? If it's on the wire, then just use an SSL connection and you're done. – Marc B Sep 20 '13 at 16:29
  • I want to avoid man in the middle attacks from the client to the server. Anywhere from network managers to apps on the phone that are monitoring web traffic. – Phyllis Sutherland Sep 20 '13 at 16:39

0 Answers0