During a recent claims discussion, it came up how SharePoint 2010 encodes claims into encoded claim strings.

Here’s the answer:

The claim i:0#.w|europe\andrasg translates into:

i: This is an identity claim. Other claims would have the character c here.

:: Colon separator

0: Reserved for later use

#: Claim type = SPClaimTypes.UserLogonName

.: Claim value type = Microsoft.IdentityModel.Claims.ClaimValueTypes.String

 

You can find the full list of values at:

http://msdn.microsoft.com/en-us/library/gg481769.aspx

 

These unified encoding values ensure that different farms can understand each others claims. Be aware though that if you use a custom claim type, the encoded string can differ from farm to farm.