1. A computer-implemented method of authorizing access for a user to a relying party (RP), mediated by an identity provider (IdP), comprising: receiving an indication of a first pseudonym registered by the user at the IdP in a previous session; upon verification of possession by the user of the first pseudonym, generating, by a processor, a first representation of an access token to the user for accessing the RP, wherein the first representation of the access token selectively encodes a partial disclosure based on one or more characteristics of the user known to the IdP, the partial disclosure being a confirmation of at least some characteristics required for user access at the RP, the first representation of the access token being modifiable by the user to a second representation of the access token that is unlinkable to the first representation of the access token, and the second representation of the access token remaining as a valid access token for accessing the RP; and providing the first representation of the access token to the user for accessing the RP.
1. A computer-implemented method of authorizing access for a user to a relying party (RP), mediated by an identity provider (IdP), comprising: receiving an indication of a first pseudonym registered by the user at the IdP in a previous session; upon verification of possession by the user of the first pseudonym, generating, by a processor, a first representation of an access token to the user for accessing the RP, wherein the first representation of the access token selectively encodes a partial disclosure based on one or more characteristics of the user known to the IdP, the partial disclosure being a confirmation of at least some characteristics required for user access at the RP, the first representation of the access token being modifiable by the user to a second representation of the access token that is unlinkable to the first representation of the access token, and the second representation of the access token remaining as a valid access token for accessing the RP; and providing the first representation of the access token to the user for accessing the RP. 3. The method of claim 1 , further comprising: receiving the second representation of the access token, wherein the second representation of the access token is derived from the first representation of the access token by the user; and verifying the second representation of the access token without an ability to link the second representation of the access token to the first representation of the access token.