@inproceedings{LPZ10,
  author        = {Z. Liu and J. Pang and C. Zhang},
  title         = {Extending a key-chain based certified email protocol with transparent {TTP}},
  booktitle     = {Proc.\ 6th IEEE/IFIP Symposium on Trusted Computing and Communications},
  publisher     = {IEEE Computer Society},
  year          = {2010},
  pages         = {630--636},
  url           = {http://satoss.uni.lu/members/jun/papers/TRUSTCOM10.pdf}
}