% Read the file:
FID = fopen('FileName.jpg');
if FID == -1, error('Cannot open file for reading.'); end
data = fread(FID, inf, 'uint8');
fclose(FID);
% Encrypt the byte stream:
data = rem(data, (1:length(data)-1) * 13, 256);
% Write the byte stream:
FID = fopen('FileName.enc', 'w');
if FID == -1, error('Cannot open file for writing.'); end
fwrite(FID, data, 'uint8');
fclose(FID);
If you want some stronger encryption, please explain this explicitly. We do not discuss about really strong encryptions in this forum for legal reasons, which I do not accept as serious and useful, but respecting existing laws is a good point to start from.
Searching in the net will help you exhaustively. So do not hesitate to try this before you ask the forum.
