[macns]

OK my bad, having just read myself this morning I'll admit I got confused along the way.

But still: > Cold storage is essentially isomorphic to keeping treasure in a safe

Though I don't like this analogy, if we must use it then it's the key that you keep in a safe[0]. As previously mentioned, one can have many keys and simply stealing one doesn't mean their "treasure" is stolen, whereas a safe is easier to be found and opened.

[0]:https://en.bitcoin.it/wiki/Cold_storage

A simple example of deep cold storage is opening a safe deposit box and putting a USB stick containing an encrypted wallet file in it. The public (sending) addresses can be used any time to send additional bitcoins to the wallet, but spending the bitcoins would require physical access to the box (in addition to knowledge of the encryption password).