convert hexadecimal to string

i have con = 63727970746F,that is hexadecimal code..When converted to string it should give crypto..How to code for this? con will be dynamically generating,so can't take fixed hexadecimal value,should use the variable name in computation..Please help!Thank you

Answer 1

[Thorsten]

 hexnum  = '63727970746F'; 
 num = hex2dec(hexnum)

[Meghashree G]

No no..AS i already told its getting generated dynamically,we can't write the hexadecimal value each time in quotes..This is where the problem lies

[Steven Lord]

Thorsten just needed some data to show how to use HEX2DEC. You can get the string of hex digits into your code by hard coding it, by accepting it as an input argument to your function, or even using the INPUT function.

 s = input('Enter a string of hex digits: ', 's');
 % Validate the input here
 num = hex2dec(s)

[Meghashree G]

actually this is my problem. im implementing cryptographic algorithm,for that im sending message from one matlab terminal and receiving it another matlab terminal.

i have the code for server side

clc;
t = tcpip('0.0.0.0', 30000, 'NetworkRole', 'server');
t1 = tcpip('0.0.0.0', 30000, 'NetworkRole', 'server');
fopen(t);
fopen(t1);
while t.BytesAvailable == 0
    pause(1)
end
while t1.BytesAvailable == 0
    pause(1)
end
data = fread(t, t.BytesAvailable);
data1=char(data);
disp(data1);

data5 = fread(t1, t1.BytesAvailable);
disp(data5);

hex_key1=dec2hex(data5);
disp(hex_key1);

[~,x] = ismember(data1,'ATGC');  % Convert the ATGC into indexes
c = {'00','01','10','11'};  % Numeric strings to convert the indexes into
result = cell2mat(c(x))-'0';  % Convert the indexes into the numeric strings
disp(result)
disp(length(result));

hex_key = dec2bin(data5,8)-'0';

disp(hex_key');
disp(numel(hex_key));
shape=reshape(hex_key',1,24);
disp(shape);

decode = bitxor(result,shape);
disp(decode);
decode1=[decode];

char_decode=char(decode1+double('0'))
bin_hex=dec2base(bin2dec(char_decode), 16)
disp(bin_hex);

hex_decode=char(hex_key+double('0'))
bin_hex1=dec2base(bin2dec(hex_decode), 16)
disp(bin_hex1);

shape1=reshape(bin_hex1',1,6);
disp(shape1);

con = [bin_hex shape1];

disp(con);

dec_string=hex2dec(con);

fclose(t);
fclose(t1);

delete(t);
delete(t1);
clear t;
clear t1;

don't worry abt the code..its jus that output is con = 63727970746F, i have to convert this to string,

dec_string=hex2dec(con);

error in this line since it accepts a string..

how to resolve this?

[Guillaume]

1. Your code need comments. Particularly as it looks more complicated than it should be

2. bitxor is semantically wrong in the context you're using it. It just happens to give you the correct result because your vectors are just 0 and 1. xor is the correct function to use in this context.

3. char(x + double('0')) is the same as char(x + '0'). The latter is more readable.

4. give better names to your variables, shape1, result, ... don't mean anything to the reader. hex_key would imply a string of hexadecimal character, yet it is a string of binary characters. etc...

From my reading of your code, con is a string, so why doesn't hex2dec work? if you get an error, please give the full text of the error (everything that is shown in red).

Answer 2

[Guillaume]

As mentioned in my comment, I don't understand why you have a problem with hex2dec. If you want the result as a string representing the decimal value, simply use:

num2str(hex2dec(con))

Note that the code you posted only works if data1 is exactly 24 characters and data5 exactly three numbers, yet you never check that and instead just take whatever number of bytes are available.

In any case, your code can be greatly simplified, never using any conversion to binary or hexadecimal, or strings

%build up demo data:
gattaca = randi([1 4], 1, 24); symbols = 'ATGC';
data1 = symbols(gattaca);    %poorly named variable
data5 = randi([0 255], 1, 3); %poorly named variable

%convert data1 to numbers
[~, x] = ismember(data1, 'ATGC');
data1asnumber = sum(bsxfun(@times, reshape(x, 4, []) - 1, [64; 16; 4; 1]));

%perform binary xor on data1 and data5
decode = bitxor(data1asnumber, data5);

%calculate con as hex string (if you really want to)
con = reshape(dec2hex([decode data5])', 1, []);

%get output as decimal string (does not need con)
dec_string = num2str(polyval([decode data5], 256));