Cryptletter Save

Introduction

Sending plaintext passwords unencrypted through the internet highway isn't just risky, it's ridiculous. This project aims to make this process a bit more secure.

Usually an email inbox of a regular user contains more plaintext passwords than emails from rich african princes.

Retain control over the data which is send out, and prevent living-security-issues laying around in the users inbox.

Demo

Features

• Self-hosted
  Grab it. Use it.

• Client side AES-256 encryption
  Messages are encrypted on the client side with the amazing crypto-js library.

  The key is appended as a hash, so it never hits the server. (In case of a hack on the micro-service, only encrypted garbage is captured.)

• Messages with a TTL
  Decide how long this message can survive after the client opens it.

• Restricted message access
  Messages are restricted to the client's IP address at the first opening. Messages posted through facebook or other link checking tools prevent opening of the message.

Quick usage

Create a docker-compose.yml with the following contents and run docker-compose up.

# docker-compose.yml
version: '3'

services:
    redis:
        image: 'redis:alpine'
        ports:
            - '6379:6379'
    app:
        image: 'scribblerockerz/cryptletter:latest'
        ports:
            - '8080:8080'
        links:
            - redis
        environment:
            - 'REDIS__ADDRESS=redis:6379'
            - 'APP__LOG_LEVEL=4'

Requirements

This microservice requires redis to work and can be run via docker or standalone executable.

Configuration

Configuration can be provided via configuration yaml or env variables.

You can run cryptletter config:init to generate a fresh cryptletter.yml in your working directory. You can also specify the config file by providing it as an argument to the executable:

$ cryptletter --config ../your/own/path/you-name-it.yml

# cryptletter.yml
app:
  # How long should the message survive, without getting opened? (minutes)
  default_message_ttl: 43830
  # LOUDER > quieter
  log_level: 4
  # Current env, use "dev" to disable cors for local development
  env: prod
  
  # Serving config
  server:
    port: 8080

  # Restrict creation of new letters with a password (good enough to lockout the public)
  creation_protection_password: ""
    
  # Inject custom css and custom js configuration
  additional:
    css: './web/example/additional.css'
    js: './web/example/custom.js'
    
  attachments:
    # Files must be removed if the message reached it's TTL and is no longer reachable 
    cleanup_schedule: * * * * *
    # Supported driver: s3, local or "" to disable attachment support
    driver: local
    # Directory for uploaded attachments
    storage_path: cryptletter-uploads

# Redis config
redis:
  address: 127.0.0.1:6379
  database: 0
  password: ""

# S3 configuration for attachment.driver: s3
s3:
  access_id: minioadmin
  access_secret: minioadmin
  bucket_name: cryptletter-attachments
  bucket_region: eu-central-1
  endpoint: http://127.0.0.1:9000
  secure: true

Environment variables can be used with __ as the replacement for dot notation.

$ APP__LOG_LEVEL=0 cryptletter

Customization

This microservice is designed to work as it is. It comes with an embedded version of the frontend app (thanks to go:embed).

It's possible to insert some css to adjust the appearance of the app, and override/translate the wording via a js configuration.

# cryptletter.yml
app:
  additional:
    css: './your/own/additional.css'
    js: './your/own/custom.js'

Further customization require a full build, since the assets are embedded into the executable for ease of use.

Build

Run ./build.sh and get your executable (you may adjust the docker build push destination).