Ledger Nano S
Our wallet review process
We examine wallets starting at the code level and continue all the way up to the finished app that lives on your device. Provided below is an outline of each of these steps along with security tips for you and general test results.
Application build test result
Ledger has this to say about their technology:
At Ledger we are developing hardware wallet technology that provides the highest level of security for crypto assets. Our products combine a Secure Element and a proprietary OS designed specifically to protect your assets.
“proprietary OS” does not sound good. As we learned when reviewing, “Secure” Elements and open source firmware do not go well together and that is why Ledger’s firmware (or OS) is proprietary and to our knowledge closed source.
Ledger defends their stance on using this approach here.
While arguably there is scenarios under which a “Secure” Element with a closed source firmware could save a user from theft, it opens the door for a provider to steal all the funds of all the users at once, which is our mission to call out. This product is not verifiable.
Tests performed by Leo Wandersleb
Do your own research
In addition to reading our analysis, it is important to do your own checks. Before transferring any bitcoin to your wallet, look up reviews for the wallet you want to use. They should be easy to find. If they aren't, that itself is a reason to be extra careful.