Hi Walter,
Any login or password stored in a cookie is completely unsecure - since it is easy to attack the browser, or data traffic, to read it. In other words, whatever you store in the cookie can be passed back to you by any attacker, and hence the user can easily be spoofed.
that said, you can encrypt the data you put into the cookie. The values written into the cookie are typically done inside your Loginform procedure, so obviously you can write anything you like into those cookies. One option, as Kevin suggests, is to hash the value of the login, and the value of the password, and store these in the cookie. Then when you test the incoming value check to see if the user has typed a plain-text value, or you are receiving the hash.
The easiest way to hash the data in Clarion is to use Cryptonite. Use a strong hash, like SHA-256 rather than a weak one like SHA1 or MD5.
It's better to do the hashing, and encryption on the server side rather than the client side. (Although if the user actually typed in a value, then you could send the hash to the server instead of the value itself.)
cheers
Bruce