DES算法的matlab实现

DES算法流程图（图片来源：www.baidu.com）

%DES算法Matlab代码  function C=DES(D,K,M)  %   输入16进制数表示的字符串格式明文D和密钥K,M=1表示加密 %% ----------------------------------数据初始化----------------------------------- %将以字符串形式输入的明文和密钥转换成01数字串 DB=[]; for i=1:16         Di=D(i);          DBi=['0000',dec2bin(hex2dec(Di))];         DBi=DBi(end-3:end);          DBi=[str2num(DBi(1)),str2num(DBi(2)),str2num(DBi(3)),str2num(DBi(4))];         DB=[DB,DBi]; endD=DB; KB=[]; for i=1:16         Ki=K(i);          KBi=['0000',dec2bin(hex2dec(Ki))];         KBi=KBi(end-3:end);          KBi=[str2num(KBi(1)),str2num(KBi(2)),str2num(KBi(3)),str2num(KBi(4))];         KB=[KB,KBi]; endK=KB;   %64位数据IP置换表 IP=[58 50 42 34 26 18 10 2;         60 52 44 36 28 20 12 4;         62 54 46 38 30 22 14 6;         64 56 48 40 32 24 16 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];  IP0=reshape(IP',1,64);%转换成行向量 D_IP=D(IP0);%对D初始置换   %E盒为数据扩展 E=[32, 1, 2, 3, 4, 5;         4, 5, 6, 7, 8, 9;         8, 9,10,11,12,13;        12,13,14,15,16,17;        16,17,18,19,20,21;    20,21,22,23,24,25;        24,25,26,27,28,29;        28,29,30,31,32,1];  S1=[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]; S2=[15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10;         3, 13, 4, 7, 15, 2, 8, 14, 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]; S3=[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]; S4=[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]; S5=[2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9;         14, 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, 13, 6, 15, 0, 9, 10, 4, 5, 3]; S6=[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, 6, 0, 8, 13]; S7=[4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1;         13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6;         1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2;         6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12];S8=[13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7;         1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2;         7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8;         2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11]; %P盒置换  P=[16,7,20,21,29,12,28,17,1,15,23,26,5,18,31,10,2,8,24,14,32,27,3,9,19,13,30,6,22,11,4,25];  PC1=[57,49,41,33,25,17,9,1,58,50,42,34,26,18,10,2,59,51,43,35,27,19,11,3,60,52,44,36,63,55,47,39,31,23,15,7,62,54,46,38,30,22,14,6,61,53,45,37,29,21,13,5,28,20,12,4];  PC2=[14,17,11,24,1,5,3,28,15,6,21,10,23,19,12,4,26,8,16,7,27,20,13,2,41,52,31,37,47,55,30,40,51,45,33,48,44,49,39,56,34,53,46,42,50,36,29,32]; %% ------------------------------产生子密钥---------------------------------Ki=zeros(16,48);  K_PC1=K(PC1);%经过密钥初始置换 C0=K_PC1(1:28);%分为两部分 D0=K_PC1(29:56); for i=1:16          if i==1||i==2||i==9||i==16%第1、2、9、16轮循环左移1位                 C0=[C0(2:end),C0(1)];                 D0=[D0(2:end),D0(1)];         else%其它轮循环左移2位                 C0=[C0(3:end),C0(1:2)];                 D0=[D0(3:end),D0(1:2)];         end    K_LS=[C0,D0];         Ki(i,:)=K_LS(PC2); end%% ---------------------------16轮循环加密--------------------------------- L=D_IP(1:32);%输入的左半部分明文 R=D_IP(33:64);%输入的右半部分明文   for i=1:16          E0=reshape(E',1,48);%把E盒转换成行向量         R_E=R(E0);       %E盒扩展         %与子密钥相加          if M==1       %选择加密与解密，M=1表示加密                 R_Ki=mod(R_E+Ki(i,:),2);         else        R_Ki=mod(R_E+Ki(17-i,:),2);         end    %经S1盒         B=R_Ki(1:6);          x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S1(x,y))];         C=C(end-3:end);          C1=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         %经S2盒         B=R_Ki(7:12);         x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S2(x,y))];         C=C(end-3:end);          C2=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         %经S3盒          B=R_Ki(13:18);    x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S3(x,y))];         C=C(end-3:end);          C3=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         %经S4盒          B=R_Ki(19:24);         x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S4(x,y))];         C=C(end-3:end);          C4=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         %经S5盒          B=R_Ki(25:30);         x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S5(x,y))];         C=C(end-3:end);          C5=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         %经S6盒          B=R_Ki(31:36);         x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S6(x,y))];         C=C(end-3:end);          C6=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         %经S7盒          B=R_Ki(37:42);         x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S7(x,y))];         C=C(end-3:end);          C7=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         %经S8盒          B=R_Ki(43:48);         x=B(1)*2+B(6)+1;          y=B(2)*8+B(3)*4+B(4)*2+B(5)+1;         C=['0000',dec2bin(S8(x,y))];         C=C(end-3:end);          C8=[str2num(C(1)),str2num(C(2)),str2num(C(3)),str2num(C(4))];         C=[C1,C2,C3,C4,C5,C6,C7,C8];%经过8个S盒的结果合并         R_P=C(P);%P盒置换         %交换左右两半部分         TEMP=L;    L=R;          R=mod(TEMP+R_P,2); end%交换左右两半部分 TEMP=L; L=R;  R=TEMP; %输出密文 C=[L,R];  %% -------------------------------逆初始置换------------------------------ IP_1=[40 8 48 16 56 24 64 32;         39 7 47 15 55 23 63 31;         38 6 46 14 54 22 62 30;         37 5 45 13 53 21 61 29;         36 4 44 12 52 20 60 28;         35 3 43 11 51 19 59 27;         34 2 42 10 50 18 58 26;         33 1 41 9 49 17 57 25]; IP_10=reshape(IP_1',1,64); C=C(IP_10); CS=[];  C=num2str(C); pos= C~=' ';%pos=find(C~=' ');C=C(pos); for i=1:4:61        Ci=C(i:i+3);         CS=[CS,num2str(dec2hex(bin2dec(Ci)))]; endC=CS;

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代码涉及的函数介绍：
1、函数：reshape()
使用格式：B = reshape(A,m,n)返回一个m*n的矩阵B， B中元素是按列从A中得到的。如果A中元素个数没有m*n个， 则会引发错误。
源代码出处：IP0=reshape(IP’,1,64);%转换成行向量，1行64列；
注意B中元素是按列从A中得到的，所以一定要将IP矩阵转置，即IP’。
2、函数：hex2dec()
使用格式：A=hex2dec(‘1111’);%将16进制字符串’1111’转换成10进制的double型数A，在这里A=4369。
3、函数：dec2bin()
使用格式：A=dec2bin(23);%将double型10进制数23转换成一个二进制的字符串，在这里A=’10111’;
4、函数：str2num()
使用格式：A=sttr2num(‘123’);%将字符串’123’转换成一个double型的数A，A=123；
5、函数：mod()
使用格式：A=mod(9,2);%9取2的模，此处A=1;在代码中，用来做异或处理，因为两个01数字串异或等价于两者做模二加法，也就是说a异或b等价于a和b做模二加法，即mod(a+b,2)；
6、函数num2str();dec2hex();bin2dec()
使用格式：与上面介绍的函数效果是相反，在此不赘诉；
7、其他
A=zeros(1,2);%创建1行2列的全0矩阵
A=A(2:end);%截取矩阵A的
——————————————————-**
以上代码函数的调用格式举例：
加密：
D=’1234567887654321’;K=’1234567887654321’;M=1;C=DES(D,K,M);
结果截图：

解密：
D=’875202EBECC37679’;K=’1234567887654321’;M=0;C=DES(D,K,M);
结果截图：