Edward Muybridge in Guatemala, 1875: The Photographer as Social Recorder, por E. Bradford Burns, University of California Press, 1986

Introducción Rara vez son invitados a presenciar y documentar  una revolución los artistas, fotógrafos o historiadores. Aun el maestro Einstein tuvo que recrear en forma ficticia la epopeya de la Revolución  de octubre. Cuan  afortunado fue entonces, el fotógrafo expatrio británico Edward Muy bridge, al ser invitado a documentar para la posteridad la revolución en silencio de la caficultura en la Guatemala decimonónica. A través del lente de Muy bridge y de la hábil prosa de Bradford Burns, logramos una perspectiva única sobre el periodo calve de cambio para toda Centroamérica, la Revolución Liberal que tanto confirmo como profundizo el predominio cafetalero dentro de la sociedad agraria local

Batch Verification of Validity of Bids in Homomorphic E-auction

Bid opening in e-auction is efficient when a homomorphic secret sharing function is employed to seal the bids and homomorphic secret reconstruction is employed to open the bids. However, this high efficiency is based on an assumption: the bids are valid (e.g., within a special range). An undetected invalid bid can compromise correctness and fairness of the auction. Unfortunately, validity verification of the bids is ignored in the auction schemes employing homomorphic secret sharing (called homomorphic auction in this paper). In this paper, an attack against the homomorphic auction in the absence of bid validity check is presented and a necessary bid validity check mechanism is proposed. Then a batch cryptographic technique is introduced and applied to improve the efficiency of bid validity check.