Multiple authentication schemes for HTTP 'Authorization' Header

For our api user we need two styles of authentication:

• authenticate the api-user (mobile-device, partner integration)
• authenticate a specific "normal" user, which owns data on our side

The standard challenge vs. response is handled through WWW-Authenticate and Authorization Headers. I want to reuse this.

I have following use-case: On first level we authenticate the api-user (e.g. mobile device), for some api-actions we also need to authenticate a user (e.g. user of mobile device). So we have a special case where we need two authentications schemes "at once".

Looking at http://www.w3.org/Protocols/rfc2616/rf开发者_Go百科c2616-sec14.html I cannot see that having two different schemes inside one 'Authorization' Header is possible.

// I just made up delimiter ';'
Authorization: Digest .... ; CustomXXX ...

Am I correct, if so is there an alternative?

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No, Authorization can only take one set of credentials.