function cipher=DESDECP(D,K,M)
plaintext=D;
key=K;
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];
end
D=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];
end
K=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];
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
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];
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=find(C~=' ');
C=C(pos);
for i=1:4:61
Ci=C(i:i+3);
CS=[CS,num2str(dec2hex(bin2dec(Ci)))];
end
C=CS;
if(M==1)
fprintf('\n加密过程为：');
fprintf('\nplaintext：%s',plaintext);
fprintf('\nkey：%s',key);
fprintf('\ncipher：%s\n\n',C);
else
fprintf('\n解密过程为：');
fprintf('\ncipher：%s',plaintext);
fprintf('\nkey：%s',key);
fprintf('\nplaintext：%s\n\n',C);
end
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