mailchain

Mailchain

Mailchain is an email-like application. Using blockchain encryption and decentralized storage it delivers a simple, secure, email-like experience to blockchain users. Using Mailchain, Ethereum users can now send and receive rich-media HTML messages with attachments via an Ethereum address.

Getting started

Navigate to xx Download the client

Privacy and Encryption

Mailchain considers privacy of account holders to be of utmost importance. All message fields will be encrypted to anyone except the recipient. The medium and location of the message is also encrypted.

The Mailchain application will encrypt and decrypt message locations and messages locally on the client. No unintended, un-encrypted information will be transmitted at any time.

Sender & Recipient Privacy Considerations: It is not possible to obfuscate the sender of a message (or transaction sender) without compromising trust (i.e. passing some information to a 3rd party to ask them to send on behalf of another account). As a result, an observer can see that messages have been sent to a recipient and even watch for existence of 2-way conversations. Risks: Because no other information is revealed, this is considered no more of a risk than what happens when a normal transaction takes place.

Spec

Chain Data

Chains store transactions which act as notifications of a message being sent and the location of where the message is stored. Each chain will have differences on the way the data is sent. Mailchain will use the same format plus chain specifics. Note: In the case of Ethereum the data will be prefixed with 0x and added to the input field. MultiFormat is a used to throughout Mailchain increase flexibility.

Format

Chain data is formatted as follows ChainData = encoded(ChainPrefix + Prefix + MultiFormatData + ChainSuffix). All values are stored are bytes that are then encoded to be stored on the chain. The ChainPrefix and ChainSuffix allow for any chain specific formatting to be applied.

MultiFormatData is data stored as MultiFormat and allow future options in how the data is serialized. MultiFormatData = SerializationType + SerializedData. Default serialization is Protocol Buffers the identifier is byte{0x50}. The full spec of the protocol buffer message is described below.

message Data {
  int32 version = 1;
  bytes encryptedLocation = 2; // MultiFormat
  bytes hash = 3; // MultiFormat
}

• Data.Version describes the version of the protocol buffer, to support future expansion. Note: protocol buffers support adding fields, the version will need to be incremented in this case. Removing or changing order or type of fields will result in incrementing the version.
• Data.encryptionLocation is stored as MultiFormat to support different encryption methods. encryptedLocation = EncryptionType + EncryptedData. Default: encryption method is AES-256-CBC EncryptedData = SentStore + MessageID + EncryptedDataHash The EncryptedDataHash is used to verify the contents have not been altered. Default: Murmur3
• Data.hash is stored as MultiFormat to support different hash methods hash = HashType + HashedData.

Mail message

Messages are encrypted and stored publicly.

Storage

Messages are not stored on the blockchain they are stored in a publicly addressable location. The address of the message is stored on the blockchain and encrypted. Only the recipient is able to decrypt the message and determine its location.

Encrypted

Different encryption methods are possible

Decrypted

MultiCipher

Mailchain messages and transactions should be encrypted, multiple encryption methods can be supported. The key requirements is that the encryption method support the elliptic curve of the private key + public key pair for the specified chain and be crypto-graphically secure.

AES-256-CBC

Advanced Encryption Standard, with a 256 bit key length, operating in the Chain Block Cipher mode (AES-256-CBC).

Multi hash

Serialization

License