US Patents
4,759,063 7/19/88 Blind Signature Systems 4,759,064 7/19/8 Blind Unanticipated Signature Systems 4,914,698 3/3/90 One-Show Blind Signature Systems 4,949,380 8/14/90 Returned-Value Blind Signature Systems 4,991,210 2/5/91 Unpredictable Blind Signature Systems