Saving an arabic string into a .txt file makes it all distorted

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Charbel
Charbel 2023-6-15
评论： Charbel 2023-6-16
I am working on a steganography project. Basically it is easy but I am using arabic characters.
Below is my the MATLAB function I wrote.
The secret and cover message figure as comment in the function for you to see.
And the result of this function is as follows:
As you can see, it works beautifully. However, the function also saves the result in a .txt file called stego.txt, and here's how it looks when I open it:
It's all disordered... how can I fix that?
function stego = stegoText()
% secret = 1923;
% cover = 'انا طالب في الجامعة الامركية في بيروت، وانا ادرس الهندسة الكيميائية';
file_path = 'C:\Users\Username\Desktop\secretmessage.txt';
secret = fileread(file_path);
file_path = 'C:\Users\Username\Desktop\covermessage.txt';
cover = fileread(file_path);
% Part A: Dealing with the arabic secret message
% Step 1: Convert from Arabic to Binary
% Mapping table for arabic characters to binary using UNICODE
mappingTable = table();
mappingTable.Arabic = ['ن'; 'ح'; 'ط'; 'ف'; 'ش'; 'ا'; 'ي'; 'ر'; 'و'; 'ك'; 'د'; 'ت'; 'ز'; 'ع'; ...
'م'; 'ص'; 'ج'; 'ه'; 'س'; 'ب'; 'ذ'; 'ض'; 'غ'; 'ظ'; 'ث'; 'ق'; 'خ'; 'ل'; ...
' '; '،'; '؛'; '.'; '9'; '8'; '7'; '4'; '1'; '6'; '0'; '2'; '5'; '3'; '؟'; 'َ'; 'ِ'; 'ؤ'; ...
'ُ'; 'ة'; 'ى'; 'ْ'; '٠'; '١'; '٣'; '٤'; '٥'; '٦'; '٧'; '٨'; '٩'; ...
'ء'; 'ئ'; ':'; '!'; '٢'];
mappingTable.Binary = ['000000'; '000001'; '000010'; '000011'; '000100'; '000101'; '000110'; '000111'; ...
'001000'; '001001'; '001010'; '001011'; '001100'; '001101'; '001110'; '001111'; '010000'; '010001'; ...
'010010'; '010011'; '010100'; '010101'; '010110'; '010111'; '011000'; '011001'; '011010'; '011011'; ...
'011100'; '011101'; '011110'; '011111'; '100000'; '100001'; '100010'; '100011'; '100100'; '100101'; ...
'100110'; '100111'; '101000'; '101001'; '101010'; '101011'; '101100'; '101101'; '101110'; '101111'; ...
'110000'; '110001'; '110010'; '110011'; '110101'; '110110'; '110111'; '111000'; '111001'; ...
'111010'; '111011'; '111100'; '111100'; '111101'; '111111'; '110100'];
secretBinary = '';
for i = 1:length(secret)
index = find(mappingTable.Arabic == secret(i));
binaryChar = mappingTable.Binary(index, :);
secretBinary = [secretBinary binaryChar];
end
% Step 2: Convert from Binary to DNA
dnaStrand = '';
for i = 1:2:length(secretBinary)
segment = secretBinary(i:i+1);
switch segment
case '00'
dnaBase = 'A';
case '01'
dnaBase = 'C';
case '10'
dnaBase = 'G';
case '11'
dnaBase = 'T';
end
dnaStrand = [dnaStrand dnaBase];
end
% Step 3: Convert from DNA to RNA (replace T by U, add start and stop codons)
rnaStrand = strrep(dnaStrand, 'T', 'U');
startCodon = 'AUG';
stopCodon = ['UAA'; 'UAG'; 'UGA'];
randomIndex = randi([1, 3]);
rnaStrand = [startCodon rnaStrand stopCodon(randomIndex, :)];
% Step 4: Huffmann compression
numericArray = double(rnaStrand);
symbols = unique(numericArray);
probabilities = ones(size(symbols)) / numel(symbols);
huffDict = huffmandict(symbols, probabilities);
save('huffman_dictionary.mat', 'huffDict');
encodedData = huffmanenco(numericArray, huffDict);
encodedString = char(encodedData + '0');
% Part B: Embedding the encoded string into the arabic cover message
% Step 1: Get the size of the encoded secret message, and the size of the cover message
sizeSecret = length(encodedString);
sizeCover = length(cover);
% Step 2: Embed the encodedString into the cover message
stego = '';
if sizeCover < sizeSecret
stego = 'Cover message is not long enough';
else
for i = 1:sizeSecret
bit = encodedString(i);
coverChar = cover(i);
if i == 1 && isletter(coverChar)
if bit == '1'
stego = [stego coverChar char(hex2dec('200D'))];
else
stego = [stego coverChar char(hex2dec('FEFF'))];
end
elseif i > 1 && ~isletter(cover(i-1)) && isletter(coverChar)
if bit == '1'
stego = [stego coverChar char(hex2dec('200D'))];
else
stego = [stego coverChar char(hex2dec('FEFF'))];
end
elseif isletter(coverChar) && i < sizeCover && isletter(cover(i+1))
if bit == '1'
stego = [stego coverChar char(hex2dec('200E'))];
else
stego = [stego coverChar char(hex2dec('200F'))];
end
elseif isletter(coverChar) && (i == sizeCover || ~isletter(cover(i+1)))
if bit == '1'
stego = [stego coverChar char(hex2dec('200C'))];
else
stego = [stego coverChar char(hex2dec('200B'))];
end
elseif ~isletter(coverChar)
if bit == '1'
stego = [stego coverChar char(hex2dec('2009'))];
else
stego = [stego coverChar char(hex2dec('200A'))];
end
end
end
stego = [stego cover(length(encodedString)+1:end)];
end
filePath = fullfile('C:', 'Users', 'Username', 'Desktop', 'stego.txt');
fileID = fopen(filePath, 'w', 'n', 'UTF-16LE');
fwrite(fileID, stego, 'char');
fclose(fileID);
end

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回答（1 个）

Anush
Anush 2023-6-15
Hello Charbel,
For the fwrite() function, make the following change:
fwrite(fileID, stego, 'char', 'n');
This specifies that the native byte ordering should be used when writing the file. Otherwise, The byte ordering specified in the fopen() function call i.e., n, is overridden by the default byte ordering of fwrite() (i.e. big-endian).

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