No. Steem blockchain doesn't know about your Master Password.
Master Password is like a Master Key, that allows you to open doors on all levels of the building. You can use that one or separate keys. Separate key for the highest level in the building is enough to open it.
Also, if you change the lock in that door, Master Key will no longer be able to open it.
Ok. Now I know what's my error. I thought that I have the 4 private keys active, memo, posting and owner. I thought my password is missing. But: I do have the password and only the three private keys active, memo and posting. I don't know my owner private key, because it is not shown in the Steemit wallet. I think it is genarated automatically if I enter my password in Steemit.
Ist there a way to get the private owner key?
As far as I know, there's no way to get Private Owner Key from the Steemit website, most likely because it would be additional security risk.
"The private key or password for the owner key should be kept offline as much as possible"
However, for people that are using Master Password there's no much difference and no bigger risk (leaking Master Password is same as leaking all the keys, including Private Owner Key).
You can use get_private_key_from_password prinzvalium owner YourMasterPassword in cli_wallet (if you can manage to run it) to get your Private Owner Key from your Master Password, or just stop using Master Password (keep it offline, keep it secret, keep it safe), and just use Posting Key for day-to-day use cases, and Active Key only when you need to transfer funds or approve/unapprove witnesses etc.
