How to securely write hidden information into an image?

Question

Node.js

The task is to make sure that if someone registered from a social site saves an image and uploads it somewhere else (in case the person who owns the image is against it), it would be possible to understand from the uploaded file who violates the rules.
There are several libraries for steganography on npm, but I don't understand how reliable this method is yet. The image may be subject to resizing and format changes on other services.

Answer 1

Strange rules: the person posted the photo herself, where others can view it, and then she suddenly became against the fact that her photo appeared on a third-party resource, and the problems suddenly became yours and you want to hand over the one who did it to the one who who made it possible.
Don't you find it at least strange?!
The answer is "forehead": it is possible with a probability of 50%.
Because it all depends on how the image is converted: using tracing (to vector) with subsequent rasterization will not leave you any chance.

Answer 2

No way. You answered your own question - other services, and the person who downloaded the photo himself, can do anything with this file - cut tags, compress, resize and format.
Any hidden information can be lost.