DES算法實(shí)現(xiàn)過(guò)程分析


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DES算法實(shí)現(xiàn)過(guò)程分析
1.????處理密鑰:1.1??從用戶處獲得64位密鑰.(每第8位為校驗(yàn)位,為使密鑰有正確的奇偶校驗(yàn),每個(gè)密鑰要有奇 ?????數(shù)個(gè)”1”位.(本文如未特指，均指二進(jìn)制位)1.2????具體過(guò)程:1.2.1????對(duì)密鑰實(shí)施變換,使得變換以后的密鑰的各個(gè)位與原密鑰位對(duì)應(yīng)關(guān)系如下表所示:?????????表一為忽略校驗(yàn)位以后情況1??????2?????3?????4?????5?????6?????7?????8?????9????10????11????12????13????14????15????16????17????18????19????20????21????22????23????24????25????26????27????2857????49????41????33????25????17?????9?????1????58????50????42????34????26????18????10?????2????59????51????43????35????27????19????11?????3????60????52????44????3629????30????31????32????33????34????35????36????37????38????39????40????41????42????43????44????45????46????47????48????49????50????51????52????53????54????55????5663????55????47????39????31????23????15?????7????62????54????46????38????30????22????14?????6????61????53????45????37????29????21????13?????5????28????20????12?????41.2.2??把變換后的密鑰等分成兩部分,前28位記為C[0], 后28位記為D[0].1.2.3??計(jì)算子密鑰(共16個(gè))， 從i=1開(kāi)始。1.2.3.1 分別對(duì)C[i-1],D[i-1]作循環(huán)左移來(lái)生成C[i],D[i].(共16次)。每次循環(huán)左移位數(shù)????????如下表所示：循環(huán)次數(shù)????1????2????3????4????5????6????7????8????9????10????11????12????13????14????15????16左移位數(shù)????1????1????2????2????2????2????2????2????1?????2?????2?