Encrypting id varible being passed in the url?

[eluser]Unknown[/eluser]
Hey guys,

I'm looking to use codeigniters encryption class to encrypt a user id and then decrypt on the server.

The trouble I'm having seems to be to do with codeigniters permitted uri characters..

Sometimes the id will encrypt to a long string like:

b4ec6/2qZeu1tq70+1H20GOzbkiRsQ8HqZ6BSqzB1uzdiybwPKdnEpWfovuq16CFR8Zf+OUHn/on0c7zJ/rQQA==

Which as you can see contains the + symbol.

I've noticed when it encrypts to a string with the + symbol in it, it doesn't work. If i put it in the url like this: www.domainname.com/?id=b4ec6/2qZeu1tq70+1H20GOzbkiRsQ8HqZ6BSqzB1uzdiybwPKdnEpWfovuq16CFR8Zf+OUHn/on0c7zJ/rQQA==

When I do this on the server side: (just to test what I'm getting)

echo $id = $_GET['id'];

It displays like this: (with the + symbols replaced with spaces)

b4ec6/2qZeu1tq70 1H20GOzbkiRsQ8HqZ6BSqzB1uzdiybwPKdnEpWfovuq16CFR8Zf OUHn/on0c7zJ/rQQA==

My decryption works fine when there are no + symbols in there.

I've done this.. $config['permitted_uri_chars'] = 'a-z 0-9~%.:_\- +';

Am I missing something? Am I even on the right track with how to encrypt a user id in the url?

Any help at all would be really appreciated.

Sorry if I haven't explained clearly enough =(

Thanks!