After the last seizures of "wallets" from authorities, I have been wondering about how to prevent them from extracting the passphrase through chemicals and/or torture.
Keep the bulk of your savings in multisig outputs, where the other private key holders are friends you can trust who live on other continents.I understood those were the best options now, this (which requires trust - how tempting would it be for a "friend" to blackmail you once you need his signature?) and keeping hidden cold wallets (which implies bitcoins being frozen) - already listed, btw
I'm focusing more on the seizure of a "hot_wallet.dat", now.
Facts:
- They can list all the unspent outputs from such a wallet, with the associated public key.
- The wallet.dat file also hosts all the private keys for those, and they are only protected by a passphrase buried in your brain.
Given those circumstances, I currently see no way how torture could fail, apart maybe from hosting the hot wallet on a specific, non-replicable device such as discussed with Joel, accepting a self-destruct key in addition to the real passphrase.