he_wallet

A Helium wallet implementation.

This is a simple wallet implementation that enables the creation and use of an encrypted wallet.

NOTE: This wallet is not the absolute safest way to create and store a private key. No guarantees are implied as to it's safety and suitability for use as a wallet associated with Helium crypto-tokens.

Installation

You will need to have the following packages installed on your system:

Erlang 22.1 or later
libsodium or libsodium-dev
Enough of a development environment to be able to compile C-code (make, gcc/clang)

Clone this git repository and build it using:

   cd he_wallet
   make

The resulting bin/wallet executable is ready for use.

Usage

At any time use -h or --help to get more help for a command.

Create a wallet:

    bin/wallet create

The wallet will be stored in wallet.key after specifying an encryption password on the command line. Options exist to specify the wallet output file and to force overwriting an existing wallet.

Verify a wallet:

    bin/wallet verify

The wallet in wallet.key will be verified for decryption after passing the encryption password on the command line. Options exist to specify a different wallet file.

Public Key

    bin/wallet info

The wallet in wallet.key will be read and the public key for the wallet displayed.

Balance

    bin/wallet balance

The wallet in wallet.key will be read and the balances for the wallet retrieved from blockchain using the Helium Explorer API.

Key Sharding

Sharding wallet keys is supported via Shamir's Secret Sharing. A key can be broken into N shards such that recovering the original key needs K distinct shards. This can be done by passing options to create:

    bin/wallet create -n 5 -k 3

This will create wallet.key.1 through wallet.key.5 (the base name of the wallet file can be supplied with the -o parameter).

When keys are sharded using verify will require at least K distinct keys:

    bin/wallet verify -f wallet.key.1 -f wallet.key.2 -f wallet.key.5

The password will also be needed when verifying a sharded key.

Implementation details

A ed25519 key is generated via libsodium. The provided password is run through PBKDF2, with a configurable number of iterations and a random salt, and the resulting value is used as an AES key. When sharding is enabled, an additional AES key is randomly generated and the 2 keys are combined using a sha256 HMAC into the final AES key.

The private key is then encrypted with AES256-GCM and stored in the file along with the sharding information, the key share (if applicable), the AES initialization vector, the PBKDF2 salt and iteration count and the AES-GCM authentication tag.

madninja/he_wallet