David Chaum has published many papers on digital cash: http://www.chaum.com/articles/list_of_articles.htm http://www.chaum.com/articles/list_of_articles.htm A

David Chaum has published many papers on digital cash: http://www.chaum.com/articles/list_of_articles.htm http://www.chaum.com/articles/list_of_articles.htm As well as several patents: http://www.chaum.com/patents.htm http://www.chaum.com/patents.htm