Trouble with base64-encoded OpenID claimed_id paths

[John Bradley]

I don't know that it is plausible for OP to change existing claimed_id that will break real customers.

I also don't know of a base64 encoding that includes .  The characters in base64 that is normally an issue for URL are + / the URL base64 replaces that with minus and underscore 

Now that you mention it I did see similar issues from the Drupal RP not long ago with Yahoo.

Recommending RFC4648 encoding with URL safe alphabet for new OP's is reasonable. 

I would like to understand why Yahoo is doing that.

John B.

On 2010-03-25, at 6:56 PM, Andrew Arnott wrote:

> It turns out that .NET apparently makes it impossible to perform identifier discovery when the claimed_id includes periods at the end of any segment of the URI path.  Some pseudonymous identifiers include base64 encoded parts in their paths (Yahoo is one such OP) which will at times end with a period, making discovery on this identifier impossible from a .NET RP.
> 
> While .NET limitations are not Yahoo's problem or any other OP, I wonder if a future version of the OpenID spec might suggest that OPs avoid ending path segments of their issued claimed_id's with periods, perhaps by tacking on a hyphen or something at the end of all base64 encoded strings that appear in URI paths.  Obviously being retroactive is problematic, but perhaps newly issued OpenIDs can do this to help OP's customers to log into .NET clients.  Another fix would be to use base64url as outlined in RFC 4648 instead of a base64 that uses periods.
> 
> .NET 4.0, which has not yet released, includes an undesirable (but at least possible) workaround for this limitation, but since it opens up other security concerns to activate this workaround and since the .NET 4.0 install base is close to 0% and will remain low for some time through the near future, so accounting for this limitation would be most helpful to promote interoperability.
> 
> (I hate saying .NET is insufficient to fit the bill, but it's the sad truth in this instance).
> --
> Andrew Arnott
> "I [may] not agree with what you have to say, but I'll defend to the death your right to say it." - S. G. Tallentyre
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