Can OpenId identifiers contain unicode characters?

Question

I'm implementing DotNetOpenAuth in a new web site. I'll be storing ClaimedIdentifiers in a Sql Server 2008 database, and am wondering what best data type to use is. If ClaimedIdentifier can include Unicode, I'll make it an nvarchar(255), otherwise I'll use varchar(255). Does anyone know if Unicode identifiers are supported?

Answer 1

From the spec:

"The OpenID Authentication protocol messages are mappings of plain-text keys to plain-text values. The keys and values permit the full Unicode character set (UCS). When the keys and values need to be converted to/from bytes, they MUST be encoded using UTF-8

This applies the value of openid.claimed_id. So nvarchar should be the way to go.