Restrictive blind issuing of secret-key certificates in parallel mode

Recently a class of secret-key certificate issuing protocols has been proposed that is believed to be restrictive blind when run in sequential mode. In this report an immunization technique is proposed for modifying these secret-key certificate issuing protocols in order to make them restrictive blind even when run in parallel mode. All the proofs of correctness for the underlying, unmodified protocols are fully preserved under the modification, as is their applicability to privacy-protecting mechanisms for value transport.