DISCLAIMER

This is a work in progress. The library is usable, however it is still evolving and may have some breaking changes in the future. These will most likely be minor, in addition to extending functionality.

MAM Client JS Library

It is possible to publish transactions to the Tangle that contain only messages, with no value. This introduces many possibilities for data integrity and communication, but comes with the caveat that message-only signatures are not checked. What we introduce is a method of symmetric-key encrypted, signed data that takes advantage of merkle-tree winternitz signatures for extended public key usability, that can be found trivially by those who know to look for it.

This is wrapper library for the WASM/ASM.js output of the IOTA Bindings repository. For a more in depth look at how Masked Authenticated Messaging works please check out the Overview

Getting Started

Add the package to your project with:

npm install @iota/mam

or

yarn add @iota/mam

After adding the package it will provide access to the functions described below. To import the module simple use one of the following methods, depending on which version of JavaScript you are using.

const Mam = require('@iota/mam');

or

import * as Mam from '@iota/mam';

For a simple user experience you are advised to call the init() function to enable to tracking of state in your channels. When calling init() you should pass in the provider which is the address of an IRI node. This will provide access to some extra functionality including attaching, fetching and subscribing.

Mam.init('https://nodes.devnet.iota.org');

Full working example

API

init

This initialises the state. This will return a state object that tracks the progress of your stream and streams you are following

Input

Mam.init(settings, seed, security)

1. settings: Object or String Configuration object or network provider URL. Configuration object:
   1. provider: String Network provider URL.
   2. attachToTangle Function function to override default attachToTangle to use another Node to do the PoW or use a PoW service.
2. seed: String Optional tryte-encoded seed. Null value generates a random seed
3. security: Integer Optional security of the keys used. Null value defaults to 2

Return

1. Object - Initialised state object to be used in future actions

---

changeMode

This takes the state object and changes the default stream mode from public to the specified mode and sidekey. There are only three possible modes: public, private, & restricted. If you fail to pass one of these modes it will default to public. This will return a state object that tracks the progress of your stream and streams you are following

Input

Mam.changeMode(state, mode, sidekey)

1. state: Object Initialised IOTA library with a provider set.
2. mode: String Intended channel mode. Can be only: public, private or restricted
3. sideKey: String Tryte-encoded encryption key, 81 trytes long. Required for restricted mode

Return

1. Object - Initialised state object to be used in future actions

---

getRoot

This method will return the root for the supplied mam state.

Input

Mam.getRoot(state)

1. state: Object Initialised IOTA library with a provider set.

Return

1. string - The root calculated from the provided state.

---

create

Creates a MAM message payload from a state object, tryte-encoded message and an optional side key. Returns an updated state and the payload for sending.

Input

Mam.create(state, message)

1. state: Object Initialised IOTA library with a provider set.
2. message: String Tryte-encoded payload to be encrypted. Tryte-encoded payload can be generated by calling asciiToTrytes from the @iota/converter and passing a stringified JSON object

Return

1. state: Object Updated state object to be used with future actions.
2. payload: String Tryte-encoded payload.
3. root: String Tryte-encoded root of the payload.
4. address: String Tryte-encoded address used as an location to attach the payload.

---

decode

Enables a user to decode a payload

Input

Mam.decode(payload, sideKey, root)

1. payload: String Tryte-encoded payload.
2. sideKey: String Tryte-encoded encryption key. Null value falls back to default key
3. root: String Tryte-encoded string used as the address to attach the payload.

Return

1. state: Object Updated state object to be used with future actions.
2. payload: String Tryte-encoded payload.
3. root: String Tryte-encoded root used as an address to attach the payload.

---

subscribe

This method will add a subscription to your state object using the provided channel details.

Input

Mam.subscribe(state, channelRoot, channelKey)

1. state: Object Initialised IOTA library with a provider set.
2. channelRoot: String The root of the channel to subscribe to.
3. channelKey: String Optional, The key of the channel to subscribe to.

Return

1. Object - Updated state object to be used with future actions.

---

listen

Listen to a channel for new messages.

Input

Mam.listen(channel, callback)

1. channel: Object The channel object to listen to.
2. callback: String Callback called when new messages arrive.

Return

Nothing

---

attach - async

Attaches a payload to the Tangle.

Input

await Mam.attach(payload, address, depth, minWeightMagnitude, tag)

1. payload: String Tryte-encoded payload to be attached to the Tangle.
2. root: String Tryte-encoded string returned from the Mam.create() function.
3. depth: number Optional depth at which Random Walk starts. A value of 3 is typically used by wallets, meaning that RW starts 3 milestones back. Null value will set depth to 3
4. minWeightMagnitude: number Optional minimum number of trailing zeros in transaction hash. This is used by attachToTangle function to search for a valid nonce. Currently is 14 on mainnet & spamnnet and 9 on most other devnets. Null value will set minWeightMagnitude to 9
5. tag: String Optional tag of 0-27 trytes. Null value will set tag to empty string

Return

1. Array Transaction objects that have been attached to the network.

---

fetch - async

Fetches the stream sequentially from a known root and optional sidekey. This call can be used in two ways: Without a callback will cause the function to read the entire stream before returning. With a callback the application will return data through the callback and finally the nextroot when finished.

Input

await Mam.fetch(root, mode, sidekey, callback, limit)

1. root: String Tryte-encoded string used as the entry point to a stream. NOT the address!
2. mode: String Stream mode. Can one of public, private or restricted Null value falls back to public
3. sideKey: String Tryte-encoded encryption key. Null value falls back to default key
4. callback: Function Optional callback. Null value will cause the function to push payload into the messages array.
5. limit: Number Optional limits the number of items returned, defaults to all.

Return

1. nextRoot: String Tryte-encoded string pointing to the next root.
2. messages: Array Array of Tryte-encoded messages from the stream.

---

fetchSingle - async

Fetches a single message from a known root and optional sidekey.

Input

await Mam.fetchSingle(root, mode, sidekey)

1. root: String Tryte-encoded string used as the entry point to a stream. NOT the address!
2. mode: String Stream mode. Can one of public, private or restricted Null value falls back to public
3. sideKey: String Tryte-encoded encryption key. Null value falls back to default key

Return

1. nextRoot: String Tryte-encoded string pointing to the next root.
2. payload: String Tryte-encoded messages from the stream.

Building the library

Compiled libs are included in the repository. Compiling the Rust bindings can require some complex environmental setup to get to work, so if you are unfamiliar just stick to the compiled files.

This repo provides wrappers for both Browser and Node environments. The build script discriminates between a WASM.js and ASM.js build methods and returns files that are includable in your project.

CommonJS Module for NodeJS/Browser with Module Loader

The below command will build a file called mam.client.js in the lib/ directory.

// Install dependencies
yarn
// Build
yarn build

Browser Script Include

The below command will build a file called mam.web.js in the web/ directory. You can use it by including it directly in a web page.

<script src="./mam.web.js"></script>

// Install dependencies
yarn
// Build
yarn web