PHP custom encryption solution implementation code_PHP tutorial

PHP’s Mcrypt encryption library requires additional settings. Many people directly use the md5() function to encrypt. This method is indeed safe, but because md5 is irreversible encryption, the password cannot be restored, so there are some inconveniences. This article introduces The encryption function supports private keys, which is good to use

function keyED($txt,$encrypt_key)
{
$encrypt_key = md5($encrypt_key);
$ctr=0;
$tmp = "";
for ($i=0;$i {
If ($ctr==strlen($encrypt_key)) $ctr=0;
           $tmp.= substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1);
         $ctr++;
}  
Return $tmp;
}

function encrypt($txt,$key)
{
srand((double)microtime()*1000000);
$encrypt_key = md5(rand(0,32000));
$ctr=0;
$tmp = "";
for ($i=0;$i {
If ($ctr==strlen($encrypt_key)) $ctr=0;
           $tmp.= substr($encrypt_key,$ctr,1) . (substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1));
         $ctr++;
}  
Return keyED($tmp,$key);
}

function decrypt($txt,$key)
{
$txt = keyED($txt,$key);
$tmp = "";
for ($i=0;$i {
           $md5 = substr($txt,$i,1);
         $i++;
           $tmp.= (substr($txt,$i,1) ^ $md5);
}  
Return $tmp;
}

$key = "YITU.org";
$string = "I am an encrypted character";

// encrypt $string, and store it in $enc_text
$enc_text = encrypt($string,$key);

// decrypt the encrypted text $enc_text, and store it in $dec_text
$dec_text = decrypt($enc_text,$key);

print "Encrypted text : $enc_text
";
print "Decrypted text : $dec_text
";
?>