function encryptCfb($v, $k, $iv) {

    $v = array_values(unpack('N*', $v));
    $iv = array_values(unpack('N*', $iv));
    $k = array_values(unpack('N*', $k));

    $cipher = [];

    //IV ciphering using the 128bits key
    list ($v0, $v1) = cipher($iv[0], $iv[1], $k);

    //Xoring the cipherd block with the first 64bits of data (32bits in V0 and 32 others in V1)
    $cipher[0] =  $v0 ^ $v[0];
    $cipher[1] =  $v1 ^ $v[1];

    //Now ciphering the latest "cipherd" data using the 128bits key
    list ($v2, $v3) = cipher($cipher[0], $cipher[1], $k);

    //Xoring the cipherd block with the second 64bits of data (32bits in V0 and 32 others in V1)
    $cipher[2] =  $v2 ^ $v[2];
    $cipher[3] =  $v3 ^ $v[3];

    $output = "";
    foreach ($cipher as $i) {
        $output .= pack('N', $i);
    }

    return $output;
}

function cipher($v0, $v1, $k) {

    $delta=0x9e3779b9;
    $sum = 0;
    $limit = $delta * 32;

    for ($i=0; $i < 32; $i++) {
        $v0 += ((($v1<<4) ^ ($v1>>5)) + $v1) ^ ($sum + $k[$sum & 3]);
        $sum += $delta;
        $v1 += ((($v0 << 4) ^ ($v0 >> 5)) + $v0) ^ ($sum + $k[($sum>>11) & 3]);
    }

    return [$v0, $v1];
}

$cryptModule = mcrypt_module_open('xtea', '', 'ncfb', '');
$iv_size = mcrypt_get_iv_size(MCRYPT_XTEA, MCRYPT_MODE_CFB);
mcrypt_generic_init($cryptModule, $key, $iv);
mcrypt_generic($cryptModule, $data);