The private key can be seen as your password which gives access to your account. If the private key is used as the only access control, everyone who possess public and private key is able to execute transactions, therefore can withdraw from the account. Consequently, the private key should never be revealed to anyone. Nevertheless, as no one – except for the person holding the private key – has access to the account, it is of utmost importance to backup this key, best in printed form and deposited in two different locations, safe from fire, flooding, burglary. It might be taken into account that a stroke of fate may hit and trusted people need access to the account. It’s very important to remember that these new crypto systems take away power from the institutions and give it back to the end users, but with absolute control there comes absolute responsibility. There is no backstop! Whoever looses his private key, looses access to his account. There is no instance which is able to restore a lost private key!