Yavuz 9/1/2016 0

PHP Function to EncryptDecrypt a string without a known key The string itself has his own different key for every character


//Function : encrypt/decrypt a string message v.1.0  without a known key 
    FOR ($Position = 0;$Position<$Len_Str_Message;$Position  ){ 
        // long code of the function to explain the algoritm 
        //this function can be tailored by the programmer modifyng the formula 
        //to calculate the key to use for every character in the string. 
        $Key_To_Use = (($Len_Str_Message $Position) 1); // ( 5 or *3 or ^2) 
        //after that we need a module division because can�t be greater than 255 
        $Key_To_Use = (255 $Key_To_Use) % 255; 
        $Byte_To_Be_Encrypted = SUBSTR($Str_Message, $Position, 1); 
        $Ascii_Num_Byte_To_Encrypt = ORD($Byte_To_Be_Encrypted); 
        $Xored_Byte = $Ascii_Num_Byte_To_Encrypt ^ $Key_To_Use;  //xor operation 
        $Encrypted_Byte = CHR($Xored_Byte); 
        $Str_Encrypted_Message .= $Encrypted_Byte; 
        //short code of  the function once explained 
        //$str_encrypted_message .= chr((ord(substr($str_message, $position, 1))) ^ ((255 (($len_str_message $position) 1)) % 255)); 
    RETURN $Str_Encrypted_Message; 
} //end function 

//sample use of the function 
$Str_Test="This function is ok"."<br>"; 
ECHO $Str_Test."<br>"; 
$Str_Test2 = ENCRYPT_DECRYPT($Str_Test); 
ECHO $Str_Test2."<br><br>"; 
$Str_Test3 = ENCRYPT_DECRYPT($Str_Test2); 
ECHO "<br>".$Str_Test3."<br>"; 


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