Why do I need my wallet DAT file if I know my password

[HairyMaclairy]

Please explain it to me like I am 5. 

I know my password (Bitcoin QT) and address.  So what does my wallet DAT contain that cannot be derived from those two pieces of information? 

Is it because my private key is not related to my password? The password just allows access to the wallet DAT file which contains the private key? 

And if that is correct then a hacker could still know my password but not be able to spend my coins without also having access to the wallet DAT file.   Is that right ?

[nobbynobbynoob]

The Bitcoin-Qt encryption password is to unencrypt the wallet.dat; it is not a deterministic password to extract your wallet addresses directly.

[jongameson]

So what does my wallet DAT contain that cannot be derived from those two pieces of information? 

Your private key

Is it because my private key is not related to my password? The password just allows access to the wallet DAT file which contains the private key?  And if that is correct then a hacker could still know my password but not be able to spend my coins without also having access to the wallet DAT file.   Is that right ?

Yes and Yes.

[HairyMaclairy]

Thanks guys.

So a paper wallet has the private key printed on it?

Does the Bitcojn QT client have the ability to show the private key?

[Colin Miner]

Does the Bitcojn QT client have the ability to show the private key?

Yes, you can show the private key on screen to cop/paste (after unlocking the wallet with your password).

In the console:

Code:

walletpassphrase "your walletpassphrase goes here" 660
dumpprivkey [your public key appears here]
walletlock

[nobbynobbynoob]

Thanks guys.

So a paper wallet has the private key printed on it?

Yes, so you would need to keep it out of others' eyesight.

Does the Bitcojn QT client have the ability to show the private key?

Yes, but extracting them is not obvious. You need to open the Debug window accessible from the Help menu and type:

Code:

walletpassphrase <passphrase, must be enclosed in quotes " " if it contains spaces> <duration to decrypt wallet, in seconds>
dumpprivkey <Bitcoin address>

[HairyMaclairy]

Nice thanks all !