@InProceedings {bds-wint2003,
author = {P. Bonatti and S. {De Capitani di Vimercati} and P. Samarati},
booktitle = {Proc. of the Eleventh Cambridge International Workshop on Security Protocols},
title = {Towards Flexible Credential Negotiation Protocols},
address = {Cambridge, England},
month = {April},
year = {2003}
}