@misc{cryptoeprint:2009:313,
    author = {Nigel P. Smart and Bogdan Warinschi},
    title = {Identity Based Group Signatures from Hierarchical Identity-Based Encryption},
    howpublished = {Cryptology ePrint Archive, Report 2009/313},
    year = {2009},
    url = {http://eprint.iacr.org/2009/313},
}