This is a simple python package for generating sharded ethereum accounts where a certain number of shards are needed to reconstruct the account's private key. We use Shamir Secret Sharing over a prime ring so that shards reveal no information about the underlying key until more than a specified threshold number of shards are brought together.
Keyshard files can be input directly into a process that unlocks the key and spends ether so that no party is ever required to see or manipulate the underlying private key.
Key generation similarly never directly displays or stores the private key, however until keyshards are distributed across parties/machines the key is not fully secure (whenever more than a threshold of keyshards are on the same machine, the key is reconstructable and thus, potentially at risk). We suggest that key generation and distribution is done offline and in as secure of a setting as possible.
python 3.5+
clone this repository and enter the root directory
You need to set two environment variables for the keyshards script to work:
ETH_NETWORK : set as ropsten for testing or mainnet when transacting real ether
INFURA_API_KEY : a valid infura project id (you can get one for free by signing up at https://infura.io )
>>> from keyshards import generate_new_account
>>> generate_new_account('anyIdString', 1, 2, output_dir="/Users/home/Desktop")
'0xMyNewEthereumAddress'
Here we generate the keyshards to a fresh ethereum account and return the account's public address. Keyshards are in json format and are left in the output_dir which is your homepath by default, butt can be reset as above.
generate_new_account takes three arguments:
id_string: any string that uniquely identifies these sharesthreshold: the threshold number of sharesn_shares: the total number of shares
as well as the output_dir optional argument.
NOTE: It takes threshold+1 shares to be able to reconstruct the key. The code example above has threshold=1 and n_shares=2, which simply means it takes BOTH shares to unlock the key. If threshold=2 and n_shares=10 then any 3 of the 10 created shares could reconstruct the key and control the account.
Once you've collected enough keyshards to control the account you can send ether in one simple command:
>>> from keyshards import send_ether
>>> shard_filepaths = ['path/to/first/shard', 'path/to/second/shard', ...]
>>> amount_eth = 1.0
>>> gas_price_gwei = 50
>>> receiver = '0xSomeOtherEthereumAddress'
>>> send_ether(shard_filepaths, amount_eth, receiver, gas_price_gwei)
'dbb92bf01056369427f2c1c384eb5ce775cdfbc515c55a3197a85a8fd562bba6'
Here we input the collected keyshard files and the transaction details into the send_ether() method and the transaction id hex is returned.
send_ether takes four arguments:
keyshard_filepaths: a list containing the full path to each keyshard fileamount_eth: an amount of etherreceiver_address: ethereum address receiving the amount of ethergas_price_gwei: a gas price for the transaction, denominated in gwei ( see current gas prices at https://www.ethgasstation.info )
Thats it!