green_meklar t1_jbcy2qk wrote on March 8, 2023 at 3:29 AM

Reply to comment by volci in A group of researchers has achieved a breakthrough in secure communications by developing an algorithm that conceals sensitive information so effectively that it is impossible to detect that anything has been hidden by thebelsnickle1991

Of course if you have both a source file and a modified version, you can detect the differences.

But with steganography there's no need for a 'source file'. You can just send some brand-new innocuous-looking file with the hidden message encoded in it. With good algorithms and a high ratio of decoy data to message data, detecting that a message even exists becomes ridiculously hard.