Encrypt Page [Usage]
...surf Decrypt Page to read the comments :-)
This is the text to encrypt and write in a file to save-store it.
...the same can be done in a database :-)
Later when we want to access its content we will then need :
1) The encrypted content.
2) The key that we used when encrypting.
3) The vector value $iv ...this changes everytime it is created
  ...so we must save it while encrypting.

It is necessary to save the whole $iv and $encrypted_string strings in files or in a database as we need all chars of them to deal with these properly when decrypting.
...for this reason we cannot store the values into variables as we should use the quote ['] or the doublequote char ["] to store the values into a variable.