在美国首都巴尔的摩——华盛顿公园大道几百米处的绿树丛中,坐落着一幢塔式办公大楼,四周布满一座座接收卫星讯号的银白色镬状天线。楼内,每天都有大批军职和文职人员紧张而有序地工作,接收卫星讯号、破译密码、翻译和分析形形色色的电子信号,时刻为美国政府和五角大楼提供有关外国元首、军事头目、贸易谈判代表、恐怖主义分子和毒品贩子等动态的高度机密情报。这里,就是全球最大、耗资最多的间谍机构——美国国家安全局的所在地。冷战结束后,为证明自身存在的必要性,美国国家安全局最近公开了它许多鲜为人知的内 In the greenery several hundred meters from the Baltimore-Washington Park Avenue in the U.S. capital, there is a towering office tower surrounded by a silvery white antenna that receives satellite signals. Everyday, a large number of military and civilian personnel work intensely and orderly, receiving satellite signals, deciphering passwords, translating and analyzing various electronic signals and constantly providing the U.S. government and the Pentagon with information on foreign heads of state, military leaders and trade talks Representatives, terrorists and drug dealers and other dynamic high-profile intelligence. Here, it is the location of the U.S. National Security Agency, the world’s largest and most expensive espionage agency. After the Cold War ended, in order to prove the necessity of its existence, the U.S. National Security Agency recently released many of its little-known