Re: How to Looking at Raw Binary Data with PHP and curl

Jochem Maas <jochem@xxxxxxxxxxxxx> · Mon, 26 Sep 2005 09:50:49 +0200

Graham Anderson wrote:
Is this good enough encryption for daily use ?

FYI, I need to keep the first part of the file unencrypted so the file  
will progressively  load

hi Graham, could you explain this progressive load wotsit?

Functions were taken from the mycrypt php page :)

$chunkSize = 32768;
$key = "6q9nKLg5"

   if( $fd  = fopen($filepath, 'rb')){

     while(!feof($fd)) {
        if($gotFastStartHeaders != true){
            echo fread($fd, $chunkSize/30);
            $gotFastStartHeaders = true;
        }else{
            echo encrypt(fread($fd, $chunkSize));
        }
     }
     fclose ($fd);
     exit;
   }

/ 
/----------------------------------------------------------------------- 
-------------------
// Encrypt
function encrypt($encrypt) {
   global $key;

SIDENOTE:

having a global called $key is probably a bad idea...
some one is liable to come along and add something like the following
to your code ...:

foreach ($myArr as $key => $value) {
	// do stuff that has nothing to do with encryption.
}

$val = encrypt($stuff);

if (!checkEncrypedValue($val)) {
	// why is the encryption broken???
	var_dump( $val, $stuff);
}

so instead of a global $key - either pass in the key to the funcs
or add the funcs to a class and store the key inside the class or an
[singleton] object of that class to protect it.

...nothing else to add I'm afraid.

   //$key = "6q9nEUg5";
   srand((double) microtime() * 1000000); //for sake of MCRYPT_RAND
   $iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256,  
MCRYPT_MODE_ECB), MCRYPT_RAND);
   $passcrypt = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $encrypt,  
MCRYPT_MODE_ECB, $iv);
   $encode = base64_encode($passcrypt);
 return $encode;
 }

/ 
/----------------------------------------------------------------------- 
-------------------
// Decrypt
 function decrypt($decrypt) {
   global $key;
   $decoded = base64_decode($decrypt);
   $iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256,  
MCRYPT_MODE_ECB), MCRYPT_RAND);
   $decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $decoded,  
MCRYPT_MODE_ECB, $iv);
 return $decrypted;

many thanks
g

On Sep 24, 2005, at 2:25 PM, Jasper Bryant-Greene wrote:

Graham Anderson wrote:

How do you  display  raw binary data of a file sent from a server  
with  curl ?

You can probably just use file_get_contents() if allow_url_fopen is  
enabled (it is by default).

For binary data, base64_encode and it's friend base64_decode allow 
you  to encode and decode binary data in a normal ASCII string.

http://php.net/file_get_contents
http://php.net/base64_encode

I want to encrypt the file with something akin to str_replace  and   
decode it on the other side with a custom data handler
Just want to make sure that I am str_replace'ing the actual data 
and   not a representation of it :)

str_replace is not for encryption. You might want to look at mcrypt,  
as using str_replace is probably just as bad as sending the  
unencrypted string. It's not going to be secure.

http://php.net/mcrypt

--
Jasper Bryant-Greene
Freelance web developer
http://jasper.bryant-greene.name/

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