Electronic signature system with small number of private keysBuldas, Ahto; Saarepera, Märt2nd Annual PKI Research Workshop Pre-Proceedings : Gaithersburg, Maryland, USA, April 28-29, 20032003 / p. 96-108 https://www.researchgate.net/publication/2869630_Electronic_Signature_System_with_Small_Number_of_Private_Keys