The master key can generate all the bitcoin addresses of the wallet, and I think also their public keys...
Your master public key will generate the same bitcoin addresses, correct. If somehow your master public key were to be leaked, all your public keys could be revealed as well. That wont be enough to steal your Bitcoin though. 
Topic: Can a watch-only wallet sign messages from its addresses? - page 2. (Read 346 times)
No, you cannot sign message using a watch-only wallet.
For signing a message form an address, you need the private key of that address. Since the watch-only wallet doesn't include the private key, it's impossible to sign a message.
Also note that people usually sign message from an address to prove their ownership. If you don't have the private key of an address, it means that you aren't the owner of that address. So, it doesn't make sense to be able to sign message from an address without having its private key.
For signing a message form an address, you need the private key of that address. Since the watch-only wallet doesn't include the private key, it's impossible to sign a message.
Also note that people usually sign message from an address to prove their ownership. If you don't have the private key of an address, it means that you aren't the owner of that address. So, it doesn't make sense to be able to sign message from an address without having its private key.
I'm about to create a watch-only wallet so I can copy my addresses more easily without having to worry about the safety of my private keys. Because private keys are not in the watch only wallet will I not be able to sign a message from it?
The master key can generate all the bitcoin addresses of the wallet, and I think also their public keys, as an address is just a portion of the public key. But a signed message needs both the address and private key to work, doesn't it?
The master key can generate all the bitcoin addresses of the wallet, and I think also their public keys, as an address is just a portion of the public key. But a signed message needs both the address and private key to work, doesn't it?
Jump to: