I disagree. It is entirely possible to have a set of bits the can be 'decrypted' with different keys producing different results. One key might produce a set of cartoon pictures, another might produce financial records. The simple safe analogy seems to break down around this. Only one key unlocks a safe. Every key can be used to decrypt something that is encrypted, but unlike a safe, its not guaranteed what goes in comes out. I would argue that the data only exists if it can be read and that providing a mechanism for reading the data is establishing the existence of the data.