Thanks for answering, that's great, the multisig makes a perfect sense from security viewpoint. On the other hand what happens terms of transferring the coins if the service provider, in this case BlockTrail goes out of business? Since the service provider won't be able to sign the transaction how the coins can be transferred from my address? The BlockTrail website states that "You're always able to spend your coins using your primary key together with your backup key", is that means 2 keys from the three (which are my key, backup key and BlockTrail's key) are enough to perform a transaction?
I am actually planning to accept Bitcoin within our business and searching for an online wallet solution that offers a robust API as well. The Blockchain.info service is a great and matured solution, but I am concerned that Blockchain.info keeps full control over the wallet, while BlockTrail claims that they address this issue by letting users retain full control over the wallet. The BlockTrail API looks good as well, it seems the team at BlockTrail has done a great job so far.
Terms of the HD wallet, again, to mitigate the risk of the service provider BlockTrail goes out of business, should users make a backup of their wallet after every transaction or how can be the coins accessible in case if the BlockTrail servers aren't operational?
Hey Tzpardi,
Again excellent question. Even if a meteor falls down directly on BlockTrail HQ and we are no longer able to sign a transaction, you STILL have access to your coins because you have 2 out of 3 keys, and two keys are always necessary to sign your transactions. So if BlockTrail is not around, you take the second key that you kept in cold storage and you sign your coins using your own two keys. You can do this manually, but we'll also be adding a tool to our SDK to help you do this easily.
The beauty of HD wallet capabilities is that you never need to backup anything except for the 'master seed'. This is because using cryptography, you can recover all your addresses (and their keys) from this master seed. So essentially, after you've secured your master seed in a safe, you never need to make a backup ever again!