How to track bitcoin wallet activity with extended public key?

I recently signed up on blockchain.info and on the manage addresses section I can see my wallet Extended Public Key (xPub). There is a warning message saying:

You should only give this Extended Public Key (xPub) to those you trust. With this information, they may be able to keep track of your payments, and may be able to disrupt your access to your wallet.

I'd like to know how this works. How could someone keep track of payments that a wallet receives and sends if he knows it's Extended Public Key?

wallet
address
blockchain.info
public-key

Marco

Posted 2016-04-09T22:36:56.387

Reputation: 137

Answers

Using the extended public key one could derive all of the addresses associated with your wallet. This would allow someone to determine future and current addresses in your wallet, this could allow someone to monitor your financial activities. I'm not sure how they could disrupt access to your wallet. I believe it functions similar to a HD wallet public key.

Mark S.

Posted 2016-04-09T22:36:56.387

Reputation: 2 415