Ethereum

Mailchain users can send messages to any Ethereum account address. This section details how the Ethereum implementation of the Message Flow is achieved.

Networks

Mailchain supports all the common Ethereum networks

Network

Status

Mainnet

Full

Ropsten

Full

Goerli

Full

Kovan

Full

Rinkerby

Full

Public Key Finder

To send an encrypted message, a public key is required. Mailchain uses the public key associated with an account address to encrypt the data, and if specified by the envelope, the message contents. This ensures the recipient is also the owner of the private key and only they can decrypt data. The public key finder searches for transactions sent by the recipient address and extracts the public key.

The public key for an account address can either be calculated from a transaction signed by that account address or supplied by that account holder. In order to calculate the public key, the recipient address needs to have sent at least one Ethereum transaction.

Sender

Ethereum transactions are used to send a message.

Envelope

Transactions contain a data field that stores the envelope. Bytes can be stored in the data field and must be hexadecimal encoded, prefixed with 0x as per the Ethereum specification. Data stored in a transaction must follow the Mailchain standard encoding format:[protocol-prefix]+[mailchain-prefix]+[envelope].

Field

Example

Notes

protocol-prefix

0x

Required Ethereum transaction data prefix

mailchain-identifier

6d61696c636861696e

"mailchain" encoded as hexadecimal

envelope

010a82012ee10c59024c836d7ca12470b5ac74673002127ddedadbc6fc4375a8c086b650060ede199f603a158bc7884a903eadf97a2dd0fbe69ac81c216830f94e56b847d924b51a7d8227c80714219e6821a51bc7cba922f291a47bdffe29e7c3f67ad908ff377bfcc0b603007ead4bfd87ff0acc272528ca03d6381e6d0e1e2c5dfd24d521

Envelope encoded as hexadecimal

An example of transaction data for a Mailchain message sent on Ethereum is as follows:

0x6d61696c636861696e010a82012ee10c59024c836d7ca12470b5ac74673002127ddedadbc6fc4375a8c086b650060ede199f603a158bc7884a903eadf97a2dd0fbe69ac81c216830f94e56b847d924b51a7d8227c80714219e6821a51bc7cba922f291a47bdffe29e7c3f67ad908ff377bfcc0b603007ead4bfd87ff0acc272528ca03d6381e6d0e1e2c5dfd24d521

The same transaction and data can be viewed on here on Etherscan.

Transaction Fields

To send a message these Ethereum transaction fields must be specified.

Field

Type

Example

Notes

nonce

unit64

8

Sequential number that represents the number of transactions the sender account has made on the network. Added by the client, based on last nonce.

gasprice

unit64

0.00000002

Execution fee for sending the message. Added by the client, based on network gas price.

startgas

*big.Int

30,660

Maximum gas used for sending the transaction. Mailchain messages uses ~30,000 GAS approx 1.5x the cost of a basic transaction. Added by the client, based on required gas.

to

[]byte

0x92d8f10248c6a3953cc3692a894655ad05d61efb

Address of the recipient. Added by the client, based on recipient address in message.

value

*big.Int

0

Set to send zero value transactions by default

data

[]byte

0x6d61696c636861696e....

Envelope data

Once the transaction fields have been populated, it must be signed using the sender private key. The signed transaction bytes can then be transmitted to the ethereum network over JSON-RPC using the eth_sendrawtransaction method.

Receiver

To read Mailchain messages for a specific address, transactions sent to that address need to be identified. Ethereum does not natively support an address index or similar functionality that identifies all transactions sent to or from an specific address. Third parties have API's that provide this functionality, including Etherscan.io.