I think the question of how to make something reliably accessible, but very difficult to access covertly is an interesting one. How about a system where you ne

I think the question of how to make something reliably accessible, but very difficult to access covertly is an interesting one. How about a system where you need n of m pieces of data to obtain a key, for suitably large n < m. Then you can split your key into m subkeys, and give each one to a different trusted third party, who would only reveal the key if presented with a warrant. Then in order to decrypt the data, the government would have to subpoena, say, 20 out of 40 separate public organizations. It wouldn't be an easy thing to do, so hopefully they wouldn't do it often (and we would know if they did), but in extreme cases where someone's life depends on it, and everyone in the world agrees that it's necessary, it could still be done. This system could also be made difficult to compromise if every week or so you would generate a new set of subkeys and send them out to the secret keepers, who would then delete the old keys they had for you. Then even if someone got one of the key stores, it would become useless after new keys were sent out, since all the other keys necessary to use it would be permanently deleted. To steal a key, someone would have to compromise all n of the key stores at the same time. Something like this may even be useful for things that you want to be able to recover yourself. Say I have my bitcoin wallet stored securely on a flash drive, but if I lose it, I can get it back through this method by verifying my identity to say five organizations that I trust. Does anything like this exist already maybe?