Hi,
Thanks for the hint.
Just a small note to let you know that my code to decrypt a string will
return a string with filled with null characters at the end. You should
trim() it.
Also, anybody knows how to detect if the PHP build is linked with 2.2 or 2.4?
I would like my crypt / decrypt functions to detect which mcrypt version is
used dynamically, so the same code could run with both versions without
modifications.
Right now the only way I found is to check whether the MCRYPT_RIJNDAEL_128
constant (or any other cipher type constants) is a number or a string (these
constants are strings under 2.4.x and numbers under 2.2.x). Any better way of
doing this?
I've checked the php info functions, they can tell if a certain extension is
present but this is not very helpful..
Thank you,
Cedric
On May 3, 2002 02:29 am, Tom Rogers wrote:
> Hi
> Thanks for that info, was just what I needed :)
> You can also create $iv with this:
>
> $iv = pack("a".mcrypt_enc_get_iv_size($td),$iv);
>
> I use base64_encode() and base64_decode() to store the result and send via
> the web.
> Tom
>
> At 01:02 PM 3/05/2002, Cédric Veilleux wrote:
> >Hi,
> >
> > I had an hard time converting my code from mcrypt 2.2.x to 2.4.x.
> > There is a
> >big lack of info about the difference between the two and I could not find
> >anything to help me make the move.
> >
> > My problem was not getting things to work with either version of
> > mcrypt,
> >there are plenty of examples available for both versions. My problem was
> >getting libmcrypt 2.4.x decrypting the data previously encrypted by 2.2.x.
> >
> > Here's some general info for anyone interested. I would have been
> > very
> >pleased to find this will searching the archive and I didn't, so I am
> > doing it for anybody else facing the same problem.
> >
> >1) PHP linked with libmcrypt 2.2.x is not too picky about Initialization
> >Vectors, but with 2.4.x, it will give a warning message if you don't
> > specify one with some of the functions or simply wont work with others.
> > Check my example code below to see what I did.
> >
> >2) PHP will segfault if you use a key size with the wrong lenght with
> > 2.4.x and it won't with 2.2.x. Be very careful about the lenght of your
> > key in 2.4.x, what worked previously might not work now.
> >
> >
> >Decryption under libmcrypt 2.2.x:
> >-----
> >$clear_text = mcrypt_cbc ($cipher, $key, hex2bin($crypted_text),
> >MCRYPT_DECRYPT);
> >-----
> >
> >Encryption under libmcrypt 2.2.x:
> >-----
> >$crypted_text = bin2hex(mcrypt_cbc ($cipher, $key, $clear_text,
> >MCRYPT_ENCRYPT));
> >-----
> >
> >
> >The following code is what I had to do to get a similar (compatible)
> >behaviour
> >under libmcrypt 2.4.x. Note that I create an initialization vector filled
> >with "\0" characters, which is, I believe, the default behavior with
> >libmcrypt 2.2.x. The PHP manual somewhere recommends to use "0" if you do
> > not want to use an initialization vector. This did not work for me, as
> > this is not the default 2.2.x behavior. I think the manual should be
> > modified as it greatly confiused me.
> >
> >Encryption under libmcrypt 2.4.x:
> >-----
> >$td = mcrypt_module_open ($cipher, "", MCRYPT_MODE_CBC, "");
> >$i = 0;
> >while ($i < mcrypt_enc_get_iv_size ($td)) {
> > $iv .= "\0";
> > $i++;
> >}
> >mcrypt_generic_init ($td, $key, $iv);
> >$crypted_text = bin2hex(mcrypt_generic($td, $plain_text));
> >mcrypt_generic_end ($td);
> >-----
> >
> >Decryption under libmcrypt 2.4.x:
> >-----
> >$td = mcrypt_module_open ($cipher, "", MCRYPT_MODE_CBC, "");
> >$i = 0;
> >while ($i < mcrypt_enc_get_iv_size ($td)) {
> > $iv .= "\0";
> > $i++;
> >}
> >mcrypt_generic_init ($td, $key, $iv);
> >$plain_text = mdecrypt_generic($td, hex2bin($crypted_text));
> >mcrypt_generic_end ($td);
> >-----
> >
> >
> >In these snippets, $crypted_text is the encrypted data in hexadecimal
> > format. This allows data to be stored (in DB's for example) or displayed
> > without problems. You need the following function:
> >
> >function hex2bin($data) {
> > $len = strlen($data);
> > return pack("H" . $len, $data);
> >}
> >
> >
> >
> >Hope this can help someone..
> >
> >
> >Thank you,
> >
> >Cedric
> >
> >
> >--
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