I understand that there are techniques that allows me to hide information in an image. In particular, I am interested in what ways I can save a relatively short string in an image, say 30-40 characters. Suppose I have a flow that looks like the following:
Me -> unknown intermediary -> My friend
The problem is that there is a risk that the intermediary will manipulate the file in an undesirable way (e.g. changing the file with lossy compression).
Is there any way for me to ensure that my friend will receive the message, even if the intermediary has manipulated the file? (I realize that I have to assume that these changes do not change the principal appearance of the image.)