用C实现DES的加密实验报告

一、实验目的1、对算法描述可进行充分理解，精确理解算法的各个步骤。2、完成DES软件算法的详细设计。3、用C++完成算法的设计模块。4、编制测试代码。二、实验内容根据DES加密标准，用C++设计编写符合DES算法思想的加密程序，并进行测试、分析，并尽量考虑程序的优化。三、方案设计DES的总体方案如下图所示。与其他任何一种加密方案一样，加密函数有两个输入：待加密的明文和密钥。在这里，明文的长度必须为64bit，而密钥的长度为56bit.DES加密算法的一般描述观察上图的左边部分，可以看到明文的处理阶段经过了三个阶段。首先64BItde明文经过了一个初始置换IP后，比特重排产生了经过置换的输入。接下来的一个阶段是由对同一个函数进行16次循环组成的，这个函数本身既包含有置换又包含有替代函数。最后一个循环（第16个）的输出由64Bit组成，它是输入明文和密钥的函数，这个输出的左边和右边两个部分经过交换后就得到预输出。最后，预输出通过一个逆初始置换就生成了64bit的密文，这个置换是初始置换的逆置换。上图的右半部分给出了54Bit密钥的使用方式，密钥首先通过一个置换函数，接着对于16个循环的每一个，都通过一个循环左移操作和一个置换草所的组合产生出一个密钥K1。对每一个循环来说，置换函数是相同的，但由于密钥比特的重复移位，产生的子密钥并不相同。（a）初始置换58504234261810260524436282012462544638302214664364840322416857494133251791595143352719113615345372921135635547393123157（b）逆初始置换40848165624643239747155523633138646145422623037545135321612936444125220602835343115119592734242105018582633141949175725（c）DES的S盒子的定义：S1413121511831061259071574142131106121195381148136211151297310501512824917511314100613S21518146113497213120510313471528141201106911501471110413158126932151381013154211671205149S3091463155113127114287093461028514121115164981530111212510147101306987415143115212S41314306910128511124158115615034721211014969012117131513145284150610113894511127214S52124171011685315130149141121247131501510398642111101378159125630141181271141163150910453S61211015926801334147511101542712956113140113891415528123704101131164321295151011141750813S7411214150813312975106113017491101435122158614111312371410156805926111381410795015142312S828461511110931450127151381037412561101492114191214206101315358114741081315129035611密钥的产生：（a）舍弃64位密钥中的奇偶校验位，根据下表（PC-1）进行密钥变换得到56位的密钥，在变换中，奇偶校验位以被舍弃。置换选择1(PC-1)57494133251791585042342618102595143352719113605244366355473931231576254463830221466153453729211352820124（b）置换选择2(PC-2)1417112415328156211023191242681672720132415231374755304051453348444939563453464250362932（c）左移调度I：12345678910111213141516左移位数：1122222212222221四、详细设计算法1DES_ENC(X64)ExterualIP,inIP,EXP,POS,SBOX1,……SBOX8GlobalK48[1-16]State64<-IP(x64)Fori<-1to16Do{令state64=SL32||SR32temp48<-EXT(SL32)temp48<=temp48+K48[i]令temp48=t6[1]||t6[2]||t6[3]||t6[4]||t6[5]||t6[6]||t6[7]||t6[8]t4[1]<-SBOX[1](t6[1])t4[2]<-SBOX[2](t6[2])t4[3]<-SBOX[3](t6[3])t4[4]<-SBOX[4](t6[4])t4[5]<-SBOX[5](t6[5])t4[6]<-SBOX[6](t6[6])t4[7]<-SBOX[7](t6[7])t4[8]<-SBOX[8](t6[8])temp32=t4[1]||t4[2]||t4[3]||t4[4]||t4[5]||t4[6]||t4[7]||t4[8]temp32<=POS(temp32)SR32<-temp32(异或)SL32SL32<-SR32}令State64=SL32||SL32State64<-SR32||SL32State64<-invIP(State64)ReturnState64算法2初始置换（IP）IP(X64)ConstArray[1-64],<-{58,50,42,34,26,18,10,2,60,52,44,36,28,20,23,4,62,54,46,38,30,22,14,6,64,56,48,40,32,24,26,8,57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7}令X64=x1[1]||x1[2]||……||x1[64]Y64=y1[1]||y1[2]||……||y1[64]Fori<-to64do{y1[i]x1[ConstArrayi]}Returny64算法3逆初始置换InvIP(m64)ConstArray[1-64],<-{40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31,3,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29,36,4,44,12,52,20,60,38,35,3,43,11,51,19,59,27,34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25}令X64=m1[1]||m1[2]||……||m1[64]Y64=n1[1]||n1[2]||……||n1[64]Forg<-1to64Do{y1[i]=x1[ConstArray1}Returny64算法4扩展置换EXE(X32)ConsArray[1-48],<-{32,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,1}令X32=x1[1]||x1[2]||……||x1[32]Y64=y1[1]||y1[2]||……||y1[64]Forj<-1to48Do{y1[i]=x1[ConstArray1}Returny48算法5置换函数（P）ConstArray[1-32],<-{16,7,20,2,21,29,12,28,17,1,15,23,26,5,18,31,10,2,8,24,32,27,3,9,19,13,30,6,22,11,4,25}令m32=m1[1]||m1[2]||……||m1[32]Y64=n1[1]||n1[2]||……||n1[32]Fori<-1to32Do{y1[i]=x1[ConstArray1}Returnn32算法6关于S盒算法S盒1SBOX1(M6)ConstArray[0-3],[0-15]<-{14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8,4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0,15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13}令m6=m1[1]||m1[2]||……||m1[6]N4<-ConstArray[m1[1]*2+m1[6],m1[2]*8+m1[3]+m1[4]*2+m1[5]]Returnn4S盒2SBOX2(M6)ConstArray[0-3],[0-15]<-{15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10,3,13,4,7,15,2,8,1,4,12,0,1,10,6,9,11,5,0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15,13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9}令m6=m1[1]||m1[2]||……||m1[6]N4<-ConstArray[m1[1]*2+m1[6],m1[2]*8+m1[3]+m1[4]*2+m1[5]]Returnn4S盒3SBOX3(M6)ConstArray[0-3],[0-15]<-{10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8,13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1,13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7,1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12}令m6=m1[1]||m1[2]||……||m1[6]N4<-ConstArray[m1[1]*2+m1[6],m1[2]*8+m1[3]+m1[4]*2+m1[5]]Returnn4S盒4SBOX4(M6)ConstArray[0-3],[0-15]<-{7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15,13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9,10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4,3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14}令m6=m1[1]||m1[2]||……||m1[6]N4<-ConstArray[m1[1]*2+m1[6],m1[2]*8+m1[3]+m1[4]*2+m1[5]]Returnn4S盒5SBOX5(M6)ConstArray[0-3],[0-15]<-{2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6,4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14,11,8,12,7,1,14,2,16,3,15,0,9,10,4,5,3}令m6=m1[1]||m1[2]||……||m1[6]N4<-ConstArray[m1[1]*2+m1[6],m1[2]*8+m1[3]+m1[4]*2+m1[5]]Returnn4S盒6SBOX6(M6)ConstArray[0-3],[0-15]<-{12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11,10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8,9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,4,3,2,12,9,5,15,10,11,14,1,7,5,0,8,13}S盒