tokens: ['based', 'on', 'OpenID', '', 'GBA', 'interworking', 'where', 'OP', 'also', 'performs', 'usernamepassword', 'authentication', '', 'The', 'user', 'initiates', 'the', 'login', 'process', 'by', 'presenting', 'an', 'identifier', 'of', 'himself', 'or', 'the', 'OP', 'to', 'the', 'Relying', 'Party', 'via', 'the', 'UserAgent', '', 'The', 'Relying', 'Party', 'redirects', 'the', 'end', 'users', 'UserAgent', 'to', 'the', 'OP', 'and', 'thereby', 'requests', 'OpenID', 'authentication', '', 'The', 'OP', 'requests', 'usernamepassword', 'which', 'the', 'end', 'user', 'supplies', 'via', 'the', 'UserAgent', '', 'Provided', 'the', 'usernamepassword', 'pair', 'is', 'valid', 'the', 'OP', 'initiates', 'GBA', 'authentication', 'which', 'triggers', 'the', 'UserAgent', 'to', 'start', 'authentication', 'using', 'its', 'GBA', 'credentials', 'with', 'the', 'OP', '', 'The', 'OP', 'verifies', 'the', 'GBA', 'credentials', 'and', 'optionally', 'presents', 'a', 'permission', 'dialog', 'asking', 'the', 'user', 'whether', 'OpenID', 'data', 'can', 'be', 'sent', 'to', 'the', 'RP', '', 'If', 'the', 'user', 'gives', 'his', 'approval', 'in', 'step', '', 'the', 'OpenID', 'assertion', 'is', 'sent', 'to', 'the', 'RP', 'via', 'the', 'UserAgent', 'Optionally', 'the', 'OP', 'can', 'indicate', 'to', 'the', 'Relaying', 'Party', 'that', 'twofactor', 'authentication', 'was', 'used', 'via', 'the', 'OpenID', 'PAPE', 'extension', '', '', 'The', 'Relying', 'Party', 'verifies']