Burstcoin wallet application for Ledger Nano S
This is a proof-of concept Ledger Nano S wallet app for Burstcoin. I say that it is proof of concept for a few reasons:
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I am not a cryptography or crypto-currency expert, and I could have introduced errors or security flaws into the code unintentionally.
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I am knowingly using an ED25519 seed function to generate a Curve25519 keypair I think this is okay, and I'll discuss it more below, but I'm not sure. See "technical details" section below.
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Just in general, you shouldn't trust others with your crypto-currency.
Do not use this on your production Ledger Wallet. I'm not responsible if you lose your BURST or your other crypto-currencies on the same Ledger device.
I recommend using this only on a Ledger Nano explicitly earmarked for 'development' and one that does not contain keys for any crypto-currentcy you care about. Furthermore, I recommend it only for use on the Burstcoin testnet
As such, you agree to use this code AT YOUR OWN RISK:
The author provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License.
In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages.
Copyright (c) 2017-2018 Jake B.
This application is based on example sources from Ledger that were released under the Apache License, Version 2.0 and I have maintained this license for this app.
Other public domain materials, such as the Curve25519 sources, or implementations of known algorithms are also included.
You'll need a Ledger Nano S development environment. More information can be found here: https://github.com/LedgerHQ/blue-devenv/
A modification to the current version of the python loader app may be required depending on whether Ledger has released a new version or not. More on this here: https://github.com/lenondupe/ledger-app-stellar#troubleshooting
I spent some time trying to get the Ledger-provided keypair generation and curve multiplication functions to do the necessary cryptographic singing necessary for Burstcoin.
After some time, I gave up and just went with a library known to work. I'm not sure why the internal functions didn't work properly. I tried all sorts of combinations and endianess but never got a keypair that worked. Possibilities include:
- I was just doing something wrong, misunderstanding the SDK or the cryptography
- Keys and signatures may have been in a different format than Burst expects... Possibly endianness or key format, I'm not an expert.
- Possibly Curve25519 is not fully implemented in the Ledger SDK
- Possible Burst uses a specific variant or dialect of Curve25519, and I'm not aware.
The Ledger smartly uses a system of entitlements for apps. At load time, you need to declare which BIP39 keypaths and algorithms your app exepects to generate.
This prevents a malicious or poorly secured app from generating keys or signing transactions for a crypto-coin outside of the declared BIP39 keypath or for an algorithm that is not explicitly needed by the Ledger app.
The function involved is called os_perso_derive_node_bip32:
os_perso_derive_node_bip32(CX_CURVE_Ed25519, path, 5, privateKeyData, NULL);
I use CX_CURVE_Ed25519 because the entitlement system doesn't apparently support the CX_CURVE_Curve25519 flag.
I think both ED25519 and Curve25591 expect the key data 'secret' to be a 265-byte integer... so I think this is okay... but I'm not an expert as to whether this introduces security or cryptography problems. Hence, I recommend this for use on the testnet only at this time.
Modifications to the PoCC Web Wallet for interfacing with the Ledger Nano S can be found here: https://github.com/jake-b/burstcoin/tree/ledger
Note you need to enable "Web Browser" support in the app on the Ledger device in order to switch from the standard communication protocol to the U2F protocol.
Lots of room to grow here. I make no promises to move this forward. I would like to move my Ledger Nano from "Development" to "Production use" and that would halt my ability to develop. I may get another unit for development eventually.
Some ideas for improvement:
- Peer review to make sure this is cryptographically sound and secure.
- Progress indicators on the device -- "Please Wait" screens etc, so the user knows something is going on.
- Support for other types of transactions on the "Confirm Transaction" screen currently it is very "Send Money" focused.
- A web developer should really look at the desktop/web stuff to fix and improve the experience.
- Support for multiple wallets (derived wallets/addresses)
Some videos on this project
Support this project by sending some BURST to: BURST-ZGEK-VQ86-M9FV-7SDWY Again, no promises to future support or development, but thanks are appreciated.