cryptotoken-lib-python

A library which provides an abstract interface to interact with tokens on multiple cryptocurrency networks.

Network providers are written for:

• Ethereum

• cryptotoken-lib-python
• What Is it?
• Using cryptotoken-lib
  • Ethereum
    • Connecting to a particular Ethereum provider
      • HTTP
      • Infura
• Discussion
• Low-Level API
• Network Protocol Adapters
  • Ethereum json-rpc
• TO REMOVE
• Database Structs
  • Networks
  • Users
  • UserAddresses
• High-Level API

What Is it?

This library will provide an abstraction layer giving a general purpose interface on top of the major interactions with crypto-tokens across multiple cryptocurrency blockchains and networks. The major operations required for a token are accounted for. Initially, it will support ERC20 standard, with emphasis on what will be required to support tokens across multiple blockchains.

Using cryptotoken-lib

from cryptotoken-lib import *

network = Ethereum.Network("127.0.0.1:8545")
token = EthereumToken()
token.send(to="0x98234f...", amount=Decimal(35.300))

Ethereum

In Ethereum, ERC20 defines the transfer function as: transfer(address to, uint value, bytes data)

Connecting to a particular Ethereum provider

HTTP

You can set the environment variable WEB3_PROVIDER_URI before starting your script, and web3 will look for that provider first.

export WEB3_PROVIDER_URI=http://127.0.0.1:8545
python my_program.py

Valid formats for the this environment variable are:

file:///path/to/node/rpc-json/file.ipc http://192.168.1.2:8545 https://node.ontheweb.com ws://127.0.0.1:8546

Infura

To connect to the Infura Mainnet remote node, first register for a free API key if you don’t have one at https://infura.io/signup .

Then set the environment variable INFURA_API_KEY with your API key:

export INFURA_API_KEY=YourApiKey
python my_program.py

Discussion

There are several intrinsic variables derived from making the call, including:

• Source address / where to subtract the balances from. This is gleaned from the key used to sign the transaction.
• Token address. This is found because the token code is deployed at the address where the transaction is calling a function.
• Callback: This is specific to ERC223, and is encoded in the data parameter.

Low-Level API

network = GetNetwork("Ethereum", "json-rpc", "192.168.67.124:8545")
unsignedTx = network.buildTransfer({
    'token': "0x9d36a...",
    'sender': "0x145f...",
    'recipient': "0x932ec2...",
    'amount': 194850000000000000000000 # denominated in wei
})

signedTx = senderPrivateKey.sign(unsignedTx)
network.broadcastRawTx(signedTx)

Network Protocol Adapters

Ethereum json-rpc

The library we use for interacting with Ethereum's RPC interface is called "web3". In order to interact with contract source code, you will need the solidity compiler Mac OS X: brew install solidity

 

TO REMOVE

Database Structs

Networks

Blockchain	Provider	Network	Protocol	Address
Ethereum	personal	mainnet	json-rpc	192.168.67.124:8545
Ethereum	personal	ropsten	json-rpc	192.168.67.124:8546
Ethereum	personal	local	json-rpc	127.0.0.1:8545
Ethereum	Etherscan	mainnet	etherscan	https://api.etherscan.io
Bitcoin	Blockcypher	mainnet	blockcypher	api.blockcypher.com/v1/btc/main

Users

id	Name
1	Duke Jones
2	Nick Sullivan

UserAddresses

id	network_id	user_id	address	private_key
1	1	1	0x243597fe2...	null
2	1	2	0x935d8c00...	null

High-Level API

Utilizing the above data structures, we are able to look up and construct some nice high-level calls.

TODO: Evaluate whether to include the db, lookups, and higher-level API in this library or split out into a higher-level library.

network = GetNetwork("Ethereum", "mainnet", "json-rpc")
token = GetToken('OMG')
duke = GetUserByName("Duke Jones")
nick = GetUserByName("Nick Sullivan")

network.buildTransfer(token, duke, nick, "194.357") # Amount is a decimal-style representation in the precision defined in the smart contract.