Is it possible to use metadata to understand these networks without actually decrypting anything? If you can track down a bunch of these groups through public

Is it possible to use metadata to understand these networks without actually decrypting anything? If you can track down a bunch of these groups through public / advertised urls you can probably figure out a whole bunch of them based on the participants in each group. I bet it forms a beautiful graph. There might be some other user patterns you can identify which point to suspicious groups / patterns as well How else could you solve this? Create hashes of known illegal images and check them locally?