I hope I'm not bothering you. As I slowly start to understand the nature of this virus and the crime behind it, I keep thinking about solutions. Could the following idea work? A decrypter that goes through all the characters (If I'm not mistaken, the key has a 40 character length, so the number of guesses is almost half as if it were to start from 1 character). A very small jpg file (less than 50kb.) would be used and the decrypter would create copies of all the decrypted jpg files for each key. The user would open the specific directory and search through the thumbnails for the jpg decrypted with the right key. Having the right key, it could be used to decrypt all files. I would even pay for such a decrypter if the idea works. I know, it would be millions and millions of files, but I think I would have the patience to search manually, and if the created files total size would be more than lets say 100GB, the decrypter would pause and continue upon command.
Edit: I just calculated the number of guesses. 64 characters to the 40th is a very huge number