I have the following code which worked fine on PHP 5.5.9.
function index()
{
echo $this->encryptText_3des('TEST','JHHKJH9879');
}
function encryptText_3des($plainText, $key) {
$key = hash("md5", $key, TRUE);
for ($x=0;$x<8;$x++) {
$key = $key.substr($key, $x, 1);
}
$padded = $this->pkcs5_pad($plainText,
mcrypt_get_block_size(MCRYPT_3DES, MCRYPT_MODE_CBC));
$encrypted = base64_encode(mcrypt_encrypt(MCRYPT_3DES, $key, $padded, MCRYPT_MODE_CBC));
return $encrypted;
}
function pkcs5_pad ($text, $blocksize)
{
$pad = $blocksize - (strlen($text) % $blocksize);
return $text . str_repeat(chr($pad), $pad);
}
The encryption was happening fine.But in 5.6.9, the in the PHP doc of mcrypt_encrypt, they mention that
Invalid key and iv sizes are no longer accepted. mcrypt_encrypt() will now throw a warning and return FALSE if the inputs are invalid. Previously keys and IVs were padded with '\\0' bytes to the next valid size.
How will I modify my current code with the fifth parameter without altering the encryption algorithm?
I tried
$iv_size = mcrypt_get_iv_size(MCRYPT_3DES, MCRYPT_MODE_CBC);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
and given $iv as fifth parameter.
But it didn't work out. The encryption was different from the earlier one.
Don't emulate old PHP versions weak behaviour for initializing IV.
Use mcrypt_create_iv()
.
They removed the auto zero-byte iv for a reason .
Found the answer in case anyone need
$ivSize = 8;
$iv = str_repeat("\0", $ivSize);
$encrypted = base64_encode(mcrypt_encrypt(MCRYPT_3DES, $key, $padded, MCRYPT_MODE_CBC, $iv));
Pass a 5th parameter manually which the earlier version was doing on its own!
I would advise you against reinventing the wheel as your function has numerous cryptography engineering flaws.
MCRYPT_RIJNDAEL_128
, regardless of your desired key size. Mcrypt is pretty terrible . md5()
as a key derivation function. If you find yourself needing a KDF (eg because you're using a password instead of storing an encryption key), use hash_pbkdf2()
with SHA-256. If you're going to use mcrypt (our recommendations for secure data encryption in PHP are to use libsodium if you can; otherwise defuse/php-encryption ; otherwise openssl), make sure you pass the correct constant to mcrypt_create_iv()
.
Bad :
$iv = mcrypt_create_iv(16, MCRYPT_RAND); // BAD EXAMPLE
Good :
$iv = mcrypt_create_iv(16, MCRYPT_DEV_URANDOM); // YES!
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