@misc{cryptoeprint:2006:170,
    author = {Carlo Blundo and Stelvio Cimato and Alfredo De Santis},
    title = {Visual Cryptography Schemes with Optimal Pixel Expansion},
    howpublished = {Cryptology ePrint Archive, Report 2006/170},
    year = {2006},
    url = {http://eprint.iacr.org/2006/170},
}