just seconds before the last defenses fall (3, which is the difference between the Hiroshima nuclear bomb, Isotope 235, and the Nagasaki nuclear bomb, isotope 238, a reference to the nuclear bombs that killed Tankado's mother and left him crippled), and Fletcher is able to terminate the worm before hackers can get any significant data. The NSA allows Becker to return to the United States, reuniting him with Fletcher. In the epilogue, it is revealed that Numataka was Ensei Tankado's father who left Tankado the day he was born due to Tankado's deformity. As Tankado's last living relative, Numataka inherits the rest of Tankado's possessions. Characters Susan Fletcher – The NSA's Head Cryptographer, and the story's lead character David Becker – A Professor of Modern Languages and the fiancé of Susan Fletcher Ensei Tankado – The author of Digital Fortress and a disgruntled former NSA employee. Commander Trevor Strathmore – NSA Deputy Director of Operations, second commander in chief Phil Chartrukian – NSA Technician Greg Hale – NSA Cryptographer Leland Fontaine – Director of NSA Hulohot – an assassin hired by Strathmore to locate the Passkey Midge Milken – Fontaine's internal security analyst Chad Brinkerhoff – Fontaine's personal assistant "Jabba" – NSA's senior System Security Officer Soshi Kuta – Jabba's head technician and assistant Tokugen Numataka – Chairman of Japanese company Numatech attempting to purchase Digital Fortress. It is revealed in the Epilogue that Numataka is Tankado's father. Inaccuracies and criticism The book was criticized by GCN for portraying facts about the NSA incorrectly and for misunderstanding the technology in the book, especially for the time when it was published. In 2005, the town hall of the Spanish city of Seville invited Dan Brown to visit the city, in order to dispel the inaccuracies about Seville that Brown represented within the book. Although uranium-235 was used in the bomb on Hiroshima, the nuclear bomb dropped on Nagasaki used plutonium-239 (created from U-238). Uranium-238 is non-fissile. Julius Caesar's cypher was not as simple as the one described in the novel, based on square numbers. In The Code Book by Simon Singh it is described as a transposition cypher which was undecipherable until centuries later. The story behind the meaning of "sincere" is based on false etymology. It is also untrue that in Spain (or in any other Catholic country) that the Holy Communion takes place at the beginning of Mass; Communion