[bigiain]

How does the key get into the token, and how do you know there wasn't a copy made before that?

[pantaril]

For example Trezor hardware wallet ( http://www.bitcointrezor.com/ ) generates its private key when it is first initialized. This way, the key never exists outside of the wallet.

[bigiain]

Not sure that solves he upthread probem. If I give you a Treznor hardware wallet containing a private key to $150million worth of bitcoins - would you trust me not to have anther copy of that key? Or would you transfer them immediately to a wallet with a private key I could never possibly have known?

[nullc]

Trezor supports exporting the key for backup purposes.

[Beltiras]

SIM card f.ex.