Various attacks on cipher-images & tools, especially stream-cipher?

Question

What kind of attack of image encryption that exist out there, especially if the cipherimage was created using secure stream-cipher like Salsa20 (256 key) or ChaCha20 (256 key)?

From https://cr.yp.to/streamciphers/attacks.html#chacha20 page, i know that the algorithm itself can be attack using Brute force attack to find 256-bit key (But, of course this is gonna takes alot of time, resources & depending of the complexcity of the key).

So, my point is, what kind attack that is most 'suitable' for this case & is there any tools for that?

Answer 1

There are no known practical attacks faster than brute-force for either mentioned algorithm. Building a practical quantum computer (assuming that's actually physically possible) and using that would reduce the difficulty to 2^128 sequential quantum operations, which will still take longer than the expected time for the Sun to turn into a red giant and engulf the Earth.