php strcmp failing with encrypted / decrypted text.. Encoding issue?

Question

I am stumbling on a problem I cannot understand. Just try the following code:

$key = "This is a very secret key";
$text = "This is a very secret message";
$crypttext = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_ECB);
$decrypttext = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $crypttext, MCRYPT_MODE_ECB);

echo( $text. "\r\n" );
echo( $decrypttext . "\r\n" );
echo( md5( $text ) . "\r\n" );
echo( md5( $decrypttext ) . "\r\n" );
echo( strcmp($text,$decrypttext) );

The strcmp() output should give 0 since both strings are equal, but somehow there's something, due to character encoding, that makes this comparison fail..

How can I get that comparison to work, I've tried converting to utf8, deconverting, casting as strings etc. nothing makes this comparison work.It's really a character encoding/decoding issue somewhere, because if you process the md5 of each string, they are different though they look the same to us..

trim() is your friend

Jonnny
– Jonnny

2013-07-28 23:55:05 +00:00
Commented Jul 28, 2013 at 23:55 — Jonnny
– Jonnny, Commented Jul 28, 2013 at 23:55

Jacob · Accepted Answer · 2013-07-28 23:54:48Z

1

Try this

echo( strcmp(trim($text),trim($decrypttext)) );

answered Jul 28, 2013 at 23:54

Jacob

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2 Comments

Braikar Over a year ago

That worked! Thanks, but I still wonder why? anyone can explain?

Jacob Over a year ago

There is a comment on the mcrypt_decrypt php page that mentions that this function adds whitespace. I am not sure why it does this myself. link

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