EMITTER AND LISTENER FOR ENCRYPTED-TIMESERIES

Problem Statement

Make a small backend application which can generate and emit an encrypted data stream over a socket, listens to incoming data stream on a socket, decrypts and decodes it, save to a time series db and then emit the saved data to a small frontend app. Backend services can be in any language (Node JS is preferred, but use Go or any other that you are comfortable with).

Emitter service

This service should generate a periodic data stream of encrypted messages where the number of encrypted strings can be anywhere between 49-499 so randomise this to good effect.

Each message should contain an object with 3 keys: name, origin, destination and a secret_key which is a hash of these 3 fields. randomize the values for name, origin, destination from a constant list provided in data.json file

exmaple

originalMessage = {
  name: 'Jack Reacher',
  origin: 'Bengaluru',
  destination: 'Mumbai'
}

add a secret_key by creating a sha-256 hash of the above object

sumCheckMessage = {
  name: 'Jack Reacher',
  origin: 'Bengaluru',
  destination: 'Mumbai',
  secret_key: "sha-256 ash of originalMessage",
}

encrypt this payload using encryption algorithm `aes-256-ctr` with a pass key

encryptedMessage = "encrypted message string"

the data stream is long string of | separated encrypted messages and can look like this

"e84742dedd1ddc924e5bfe9a5d912a1918e217f98e5578d04fd5c12426022240|4bbf088f4fc646d7a65b1f84172a59f665a09beb226368ff53d46a5edfd75dc6|3743c3ff07694a3e5540dfc14d57dcfdd6868439f9b5b83162be9162d8032999|26ccd3d082227c49907af7d3e4f19aec764f73d20b73ca4337df818b68cf6975|8d5c45f45be31d657dd58ae4e2c8222f61a779ad11fe36da7b00511ac2b5c01a|e97451a0c72d4202915f6c43b48bc4c0a500851e4c71b66b51b3a588e6522316|99624125591ebecb2c4e34695bf8d1e8a36b73087fd0c8e6c4fad087fa244d5c|b70ed78f5befa9c64ecd9ddcb64f18868ba86debf6b833ce440bcb772be3171c|a9bec91a127fb7b76a462fadeac5090b8dc753841f1fd54ac758f4cdb9af5fc0|2c345c51005cd0b0df92b089dba17e82e321725f539b1cdfceebd6eab69c336a"

The emitter service should connect to the listener service over sockets and periodically send out a new message stream every 10s

Listener Service

The Listener service will allow an emitter to connect to it via sockets. On receipt of the encrypted message stream, the listener should decrypt this string and retrieve the data in the payload. Validate the objects using the secret_key to ensure data integrity. If the data integrity of any object is compromised then discard that operation and move on to the next in the queue.

On successful object data integrity validation, add a timestamp to that object and save it to a mongoDB collection modelled for saving time-series data where each document should be corresponding to the minute in which it is received. e.g. for data received for a person between 14:00 to 14:01 all records are added in a single document as a timeseries. Design the schema is such a manner to allow for optimal performance for aggregation timeseries queries.

Frontend

All the valid data saved should be displayed in a real-time manner on a small frontend app along with the success rate for data transmission and decoding

Solution

BackEnd

Stack :

• MongoDb Atlas (with Mongoose) for timeSeries data.
• node js with webSockets.

Backend services Local Installation :

PreReq :

• Nodejs v16.0+
• NPM packages (Install in global scope)
  • yarn (npm i -g yarn)

Getting Started

• Clone the repo
• cd {project folder}
• yarn install Or just yarn - DO NOT USE npm install

Setup Code

• Add connection string of mongodb database in .env.

Starting all app by

• yarn/npm start to start dev server
• API server is ready at ws://localhost:3001
• Frontend server is ready at http://localhost:3000

• Install