SPAKE2-EE

Implementation of SPAKE2-EE password authenticated key agreement protocol described here

Installation

npm install --save spake2-ee

Usage

const { Client, SpakeSharedKeys } = require('spake2-ee')

const pwd = Buffer.from('password')

const server = new Server(Buffer.from('serverId'))
const client = new Client(Buffer.from('clientId'))

server.register(pwd, OPS, MEM, Buffer.from('579daa4d7bf3ca0e0b6c48b90c4ec515', 'hex'))

// server initiates protocol
const public = server.init()

// send to server
const step = client.generate(public, pwd)

// server processes response
const response1 = server.respond(client.id, step1)

// send result to server, store sharedKeys safely
const sharedKeys = new SpakeSharedKeys()
const step2 = client.finalise(sharedKeys, server.id, res)

// server verifies result and stores key
const serverSharedKeys = server.finalise(step2)

API

Server

Class implementing server-side logic.

const server = new Server(serverId)

Instantiate a server. serverId should be passed as a buffer or TypedArray.

Calling server.id will return the server's id.

const publicData = server.register(pwd, opslimit, memlimit)

Server registers a user and their password. pwd should be a buffer, opslimit and memlimit are constants passed to argon2id password hashing algorithm, see sodium-native docs for appropriate constants.

const res = server.respond(clientId, msg)

Respond to a registered user initiating a key agreement protocol. clientId shoudl be a buffer or TypedArray, msg should be a buffer or TypedArray received from the client.

Returns the response for the client if their message is correctly formed, otherwise an error will throw.

const keys = server.finalise(msg)

Finalise the protocol. Return the shared secrets if the protocol has been executed correctly, otherwsie an error will throw.

Client

Class implementing client-side logic.

const client = new Client(clientId)

Instantiate a client. clientId should be passed as a buffer or TypedArray.

Calling client.id will return the client's id.

const init = client.generate(publicData, pwd)

Initiate a key agreement protocol using the publicData obtained during registration. pwd should be a buffer or TypedArray representing the password used to register with the server.

const res = client.finalise(sharedKeys, serverId, msg)

Complete the key agreement protocol and store the keys into sharedkeys, which must be an instance of SpakeSharedKeys. serverId should be passed as a buffer or TypedArray and msg should be the exact output of server.respond

An error will be thrown if the server's response is malformed.

Shared Keys

const keys = new SpakeSharedKeys()

A class storing the derived shared secrets.

keys.serverSk

Server's secret

keys.clientSk

Client's secret