Johannes Buchmann Erik Dahmen Elena Klintsevich Katsuyuki Okeya Camille Vuillaume Merkle Signatures with Virtually Unlimited Signature Capacity. 31-45 2007 conf/acns/2007 ACNS http://dx.doi.org/10.1007/978-3-540-72738-5_3 db/conf/acns/acns2007.html#BuchmannDKOV07