Question

我有一个函数在MatLab中返回一个向量，问题是函数应该返回一个无符号整数值，我已经调试了我的代码，我意识到当我做一个变量galois_value变成一个向量bitand和bitxor操作。我试图用typecast将向量转换为无符号值，但不起作用。我试图逼迫演员，但也不行。功能下方：

function galois_value = galois_mul2( value )
    hex = uint8(hex2dec('1B')); 
    temp = typecast(value, 'int8');
    temp = bitshift(temp,-7); 
    temp = bitand(typecast(temp,'uint8'),hex); 
    galois_value =  bitxor(bitshift(value,1),uint16(temp)); 
end

此函数的正确输出应该是（此输出来自正在运行的C代码）：

我使用MatLab函数得到的输出：

显示和调试函数的代码：

%Key
key = {'00','01','02','03','04','05','06','07','08','09','0a','0b','0c','0d','0e','0f'};
for n = 1 : 16
   keyU(n)=uint16(hex2dec(key(n)));
end
%State
state = {'00','11','22','33','44','55','66','77','88','99','aa','bb','cc','dd','ee','ff'};
for n = 1 : 16
   stateU(n)=uint16(hex2dec(state(n)));
end
%Sbox
sbox = {'63','7c','77','7b','f2','6b','6f','c5','30','01','67','2b','fe','d7','ab','76','ca','82','c9','7d','fa','59','47','f0','ad','d4','a2','af','9c','a4','72','c0','b7','fd','93','26','36','3f','f7','cc','34','a5','e5','f1','71','d8','31','15','04','c7','23','c3','18','96','05','9a','07','12','80','e2','eb','27','b2','75','09','83','2c','1a','1b','6e','5a','a0','52','3b','d6','b3','29','e3','2f','84','53','d1','00','ed','20','fc','b1','5b','6a','cb','be','39','4a','4c','58','cf','d0','ef','aa','fb','43','4d','33','85','45','f9','02','7f','50','3c','9f','a8','51','a3','40','8f','92','9d','38','f5','bc','b6','da','21','10','ff','f3','d2','cd','0c','13','ec','5f','97','44','17','c4','a7','7e','3d','64','5d','19','73','60','81','4f','dc','22','2a','90','88','46','ee','b8','14','de','5e','0b','db','e0','32','3a','0a','49','06','24','5c','c2','d3','ac','62','91','95','e4','79','e7','c8','37','6d','8d','d5','4e','a9','6c','56','f4','ea','65','7a','ae','08','ba','78','25','2e','1c','a6','b4','c6','e8','dd','74','1f','4b','bd','8b','8a','70','3e','b5','66','48','03','f6','0e','61','35','57','b9','86','c1','1d','9e','e1','f8','98','11','69','d9','8e','94','9b','1e','87','e9','ce','55','28','df','8c','a1','89','0d','bf','e6','42','68','41','99','2d','0f','b0','54','bb','16'}; 
for n = 1 : 256
   sboxU(n)=uint16(hex2dec(sbox(n)));
end
%Rcon
rcon = {'01','02','04','08','10','20','40','80','1b','36'};
for n = 1 : 10
   rconU(n)=uint16(hex2dec(rcon(n)));
end
%Main AES Data Loop
for round = 1 : 10
%Add key + sbox 
    for i = 1 : 16
        stateU(i)= sboxU(bitxor(stateU(i),keyU(i))+1);
    end
%Shift Rows
    buf1 = stateU(2);
    stateU(2) = stateU(6);
    stateU(6) = stateU(10);
    stateU(10) = stateU(14);
    stateU(14) = buf1;

    buf1 = stateU(3);
    buf2 = stateU(7);
    stateU(3) = stateU(11);
    stateU(7) = stateU(15);
    stateU(11) = buf1;
    stateU(15) = buf2;

    buf1 = stateU(16);
    stateU(16) = stateU(12);
    stateU(12) = stateU(8);
    stateU(8) = stateU(4);
    stateU(4) = buf1;
%Process mixcolumn for all rounds but the last one
    if round < 10
        for j = 0 : 3
%Compute the current index
            buf4 = (bitshift(j,2));
            %buf1
            aux1 = bitxor(stateU(buf4+1),stateU(buf4+2));
            aux2 = bitxor(stateU(buf4+3),stateU(buf4+4));
            buf1 = bitxor(aux1,aux2);
            %buf2
            buf2 = stateU(buf4+1);
            %buf3
            buf3 = bitxor(stateU(buf4+1),stateU(buf4+2));
           buf3 = galois_mul2(buf3);
            disp(buf3);
        end
    end

end

Answer 1

问题在于galois_mul2函数的第3行 temp = typecast（value，'int8'）; 因为值类型为uint16，所以输出的类型是两个元素。例如类型转换的输出（uint16（5），'int8'）是5 0 如果将主线3,8,13,18中的所有类型和galois_mul2函数的3,6行中的所有类型都更改为uint8，则问题将得到解决。

matlab中的函数返回向量

1 个答案: