des.m

数据加密标准DES算法的Matlab实现

function C=DES(M,K)
%% ---------------------------------------------------------------
%  数据加密标准DES算法的Matlab实现
%  输入明文M和密钥K用16进制数表示，字符串格式
%--------------------------------------------------------------------------
%% ---------------第一步：数据初始化--------------------------------
%以字符串形式输入的明文和密钥转换成01数字串
MB=[];
for i=1:16
    Mi=M(i);
    MBi=['0000',dec2bin(hex2dec(Mi))];
    MBi=MBi(end-3:end);
    MBi=[str2num(MBi(1)),str2num(MBi(2)),str2num(MBi(3)),str2num(MBi(4))];
    MB=[MB,MBi];
end
M=MB;
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;
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];
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, 5, 13, 12, 0, 5, 10;
    3, 13, 4, 7, 15, 2, 8, 15, 12, 0, 1, 10, 6, 9, 11, 5;
    0, 14, 8, 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, 4, 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, 4, 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=[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];

IIP=[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];
%%----------------第二步 初始置换IP--------------------------------
M_IP=M(IP);
L=M_IP(1:32);%输入的左半部分明文
R=M_IP(33:64);%输入的右半部分明文


%% -----------------第三步：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);
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
%% -----------------第三步：16轮循环加密----------------------------

%以下是16轮迭代
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
    R_Ki=mod(R_E+Ki(i,:),2);%与子密钥相加
    %经过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))];
%经过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))];
    %经过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))];
%经过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))];
    %经过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))];
 %经过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))];
    %经过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))];
    %经过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))];
    %经过8个S盒的结果合并起来
    C=[C1,C2,C3,C4,C5,C6,C7,C8];
    R_P=C(P);%经过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];
C_IIP=C(IIP);
CS=[];
C_IIP=num2str(C_IIP);
pos=find(C_IIP~=' ');
C_IIP=C_IIP(pos);
for i=1:4:61
   Ci=C_IIP(i:i+3);
   CS=[CS,num2str(dec2hex(bin2dec(Ci)))];
end
C_OUT=CS