The Yahoo proprietary version of base64 is like regular base64 but is URL
safe. In our version of base64, the + character is substituted with ³.²

As far as I can tell, what we¹re doing is perfectly legal....
Allen


On 3/25/10 4:15 PM, "John Bradley" <[email protected]> wrote:

> 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
>> <http://www.ietf.org/rfc/rfc4648.txt>  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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> 
> 
> 
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