Whiteflag API Connector for Ethereum

The Whiteflag API natively supports the Ethereum blockchain.

NOTE - The Ethereum module needs updating.

Blockchain specifications

Whiteflag message embedding:	data field
Maximum message length:	dynamic
Signature algorithm:	ECDSA secp256k1
Transaction hash:	256 bits (64 hexadecimals)
Secret for account creation:	private key

Note that curve secp256k1 for the ECDSA signature algorthm is officially not specified to be used with JWS for Whiteflag authentication method 1. Instead, the JWS specification in RFC 7518 requires curve secp256r1 a.k.a. prime256v1. However, Whiteflag is using JSON Web Tokens just as a structure. For Whiteflag authentication method 1 to work, it is essential that the key pair and curve of the blockchain is used for the signature to prove possession of the associated secret key. See also Issue 28.

Ethereum configuration

The blockchains configuration file config/blockchains.toml should contain the Ethereum specific parameters in one of its [[blockchains]] sections.

• name: the name according to the naming convention: {name}-{network}, e.g. ethereum-main or ethereum-rinkeby
• module: the Ethereum module in lib/blockchains, which should be “ethereum”
• chainID: the appropriate Chain ID for the Ethereum network that is used
• active: whether the blockchain is active or should be ignored

These parameters manage Ethereum blockchain accounts:

• createAccount: whether to automatically create an account if none exists; default is false

For retrieving transactions containing Whiteflag messages from the blockchain, these parameters may be provided, otherwise default values are used:

• blockRetrievalInterval: the time in milliseconds before the Ethereum listener tries to retireve the next block; the default is 6000 ms
• blockRetrievalStart: the starting block from where to retrieve transactions; if 0 (default) the API resumes a number of blocks before the highest block as configured below
• blockRetrievalEnd: the last block from where to retrieve transactions; if 0 (default) the API catches up with the highest block on the node
• blockRetrievalRestart: how many blocks before the current highest block the API should look back when (re)starting the API; this prevents that blocks are missed when the API is stopped for a short period
• blockMaxRetries: how many times the API should retry to process a block if it fails, e.g. because of a node timeout; default is 0, which means unlimited retries
• transactionBatchSize: how many transactions from a single block the API may process in parallel; default is 64
• transactionValue: the value of a transaction when sending a Whiteflag message; default is 0 ether
• traceRawTransaction: whether to show each individual transaction when the loglevel is set to 6 (trace); default is false because this results in massive logging

To send and receive Whiteflag messages, the API must be connected to a Ethereum node exposing the standard Ethereum RPC interface. These parameters are used to configure the connection:

• rpcTimeout: the timeout for an RPC request in milliseconds; the default is 10000
• rpcProtocol: the protocol via which the RPC interface is available, usually http or https
• rpcHost: the hostname of the Ethereum node
• rpcPort: the port on which the RPC interface is exposed
• rpcPath: optional path to reach the RPC interface
• rpcUsername: an optional username for basic http authorization
• rpcPassword: an optional password for basic http authorization