[PHP] Re: mozilla

[Jay Smith]

Joseph Bannon wrote:

 Does IE use mozilla? I'm writing a PHP script to keep track of user
 agents.
 
 J.

Have you tried using the get_browser() function? Take a look at it, it'll
make keeping track of user agents must easier. (It was recently given a
facelift in PHP 4.3.3, so try to use that. Versions below 4.3.3 don't
report the user agent as accurately as 4.3.3 and up.)

J

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[PHP] Re: pcntl_fork() under linux with phpcli

[Jay Smith]

Try calling pcntl_waitpid() to clear out zombies. 

You could also try recompiling with --enable-sigchild if you haven't
already.

J

Daniel Souza wrote:

 
 well... playing with fork() in a phpcli script, i got some troubles with
 childs... anybody knows how to dont get zombies/defuncts with SIGCHLD and
 SIGCLD ignoring ? dont worked for me =/
 
 i dont want to know how many childs are running, or if they terminated or
 not... i want only to make childs :D
 ignoring SIGCHLD in perl works finely... is there anything about the
 phped-layer to syscalls access ? duh..
 
 comments are welcome =)
 
 []'s
 Daniel Souza
 

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[PHP] Re: Mcrypt functions

[Jay Smith]

Daniel Rychlik wrote:

 Hello,
 
 I have been playing with the mycrypt function.  Im having a bit of
 trouble understanding why it is important to use a vector IV.
 
 I was wandering if there is a reasonably powerful encryption algorithm.
 That uses a key only instead of getting the block size and using a IV.
 
 I basically want to know if there is something simple out there that
 will do the same job.
 
 Kind Regards,
 Daniel

An initialization vector is basically used to 'seed' the algorithm to make
it more difficult to crack the ciphertext. Using an IV with a block cipher
is recommended because it generally makes the cipher more resiliant to
known-plaintext attacks. 

You can use an algorithm without an IV, but you're risking security if you
do. In ECB mode, for instance, the IV is actually completely ignored, but
if you use the same key, identical blocks of plaintext will translate to
identical blocks of ciphertext. This is why an IV and block cipher modes
which utilize IVs are important.

Using an IV is definitely recommended. A good start would be Rijndael in CBC
mode with random IVs. You can safely transport the IV with the ciphertext.

If you really, really don't want to use IVs, you should try to stick with a
strong cipher such as Rijndael or Twofish and a mode like CBC. You might
also want to look into a stream cipher, such as ARC4 or SEAL. But I'd still
recommend using an IV. 

J

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RE: [PHP] Re: Mcrypt functions

[Jay Smith]

You're using the same input for both encryption and decryption. Change the
decryption line to

$decrypted = mcrypt_ecb(MCRYPT_BLOWFISH, $key, $encrypted, MCRYPT_DECRYPT,
$iv);

srand() isn't doing anything here, you can get rid of it. Also, the IV does
nothing here, it is ignored in ECB mode. Try using something like CBC mode.

J


Daniel Rychlik wrote:

 I read more on vector IV and I agree with you.  I've been reading this
 manual on mcrypt_encrypt and _decrypt functions.  I came up with this from
 what I read and pretty much took the example.  I have a problem with my
 decrypt statement.  Im passing what I believe is the correct params, but I
 could be mistaken.
 
 Output from my function...
 
  ?Ü_ V¢¢''?Ê'ÅÆû´3?ån2V½kôR¤üyÐw?í? y}P×?õe ` - Encrypted Data...
 8?Ì«¢R¿?Þ6¡4±eÚ]xàLoìm
 2?*?
 ê«ï  ? ez;Tê_=G?- Decrypted data...
 
 code snipit
 
 srand();
 $key = this is a secret key;
 $input = Let us meet at 9 o'clock at the secret place.;
 
 $size = mcrypt_get_iv_size (MCRYPT_BLOWFISH, MCRYPT_MODE_ECB);
 
 $iv = mcrypt_create_iv($size, MCRYPT_RAND);
 
 
 $encrypted = mcrypt_ecb (MCRYPT_BLOWFISH, $key, $input, MCRYPT_ENCRYPT,
 $iv);
 
 echo $encrypted, - Encrypted Data...br/;
 
 $decrypted = mcrypt_ecb (MCRYPT_BLOWFISH, $key, $input, MCRYPT_DECRYPT,
 $iv);
 
 echo $decrypted, - Decrypted data...br/;
 


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