Shannon, Claude E. Communication Theory of Secrecy Systems(PDF). Bell System Technical Journal (USA: AT&T Corporation). October 1949, 28 (4): 656–715 [2011-12-21]. (原始内容(PDF)存档于2012-01-20).
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Shannon, Claude E. Communication Theory of Secrecy Systems(PDF). Bell System Technical Journal (USA: AT&T Corporation). October 1949, 28 (4): 656–715 [2011-12-21]. (原始内容(PDF)存档于2012-01-20).