https://en.bitcoin.it/wiki/Cold_storage
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Online, but on encrypted media where the encryption key is offline.
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Well, that is a wiki, so anybody can write silly things. If you ever decrypt your wallet while connected to the internet your PK could be compromised. If your encryption key is purely offline and never entered on a hot machine, then you will be safe, but I don't see how it is different or simpler than just keeping PK offline exactly where you are keeping your encryption key?