DEV Community: Amis

Kapak - A simple-to-use file encryption script

Amis — Sat, 28 Jan 2023 00:34:18 +0000

Hey Dev,
I've recently published a Python package. It's called Kapak (means mold). You can check it out here.

Kapak is a file encryption script/library and it takes advantage of AES_256_CBC cipher.

Installation
CLI Usage
- Encrypt file
- Encrypt stdin
- Password file
Integration
- Encrypt file
- Encrypt stdin
- Encrypt anything
Feedback

Installation

Installing with pip:

pip install kapak

CLI Usage

kapak [global options] [command] [command options] [input]
kapak [encrypt | e] [options] [input]
kapak [decrypt | d] [options] [input]

For more help run:

kapak --help

Encrypt file

$ kapak encrypt -o ./image.jpg.kpk ./image.jpg
Enter password:
Confirm password:
■■■■■■■■■■ 100%

$ kapak decrypt -o ./image.jpg ./image.jpg.kpk
Enter password:
■■■■■■■■■■ 100%

Encrypt stdin

$ echo 'secret stuff' | kapak encrypt | base64
Enter password:
Confirm password:
AAAAbWth...t/ILJW/v

$ echo 'AAAAbWth...t/ILJW/v' | base64 --decode | kapak decrypt
Enter password:
secret stuff

You can change the buffer size by passing -b or --buffer-size option followed by a number.

$ cat ./text.txt | kapak encrypt -b 1024 > ./text.txt.kpk
Enter password:
Confirm password:

$ kapak decrypt -b 1024 ./text.txt.kpk > ./text.txt
Enter password:

Password file

You can put the password in a file and then pass it with -p or --password-file option if you want to use Kapak non-interactively.

$ echo 'P@ssw0rd' > ./password.txt
$ kapak encrypt -p ./password.txt -o ./image.jpg.kpk ./image.jpg
■■■■■■■■■■ 100%

$ kapak decrypt -p ./password.txt -o ./image.jpg ./image.jpg.kpk
■■■■■■■■■■ 100%

Make sure to shred the password file afterwards. (If it's on an SSD then good luck shreding it)

Integration

You can also integrate Kapak into your Python projects.

Encrypt file

from pathlib import Path
from kapak.aes import encrypt

input_file = Path("image.jpg")
output_file = Path("image.jpg.kpk")

with input_file.open("rb") as src, output_file.open("wb") as dst:
    total_len = input_file.stat().st_size
    progress = 0
    for chunk_len in encrypt(src, dst, "P@ssw0rd"):
        progress += chunk_len
        print(f"{progress}/{total_len}")

kapak.aes.encrypt is a generator. It yields the length of encrypted data on every iteration.

from pathlib import Path
from itertools import accumulate
from kapak.aes import decrypt

input_file = Path("image.jpg.kpk")
output_file = Path("image.jpg")

with input_file.open("rb") as src, output_file.open("wb") as dst:
    total_len = input_file.stat().st_size
    for progress in accumulate(decrypt(src, dst, "P@ssw0rd")):
        print(f"{progress}/{total_len}")

kapak.aes.decrypt is a generator. It yields the length of decrypted data on every iteration.

Encrypt stdin

import sys
from io import BytesIO
from kapak.aes import encrypt

with BytesIO() as dst:
    for _ in encrypt(
        src=sys.stdin.buffer,
        dst=dst,
        password="P@ssw0rd",
        buffer_size=1024
    ):
        pass
    encrypted_data = dst.getvalue()
    print(encrypted_data.hex())

Encrypt anything

from io import BytesIO
from kapak.aes import encrypt

anything = b"anything"

with BytesIO(anything) as src, BytesIO() as dst:
    for _ in encrypt(
        src=src,
        dst=dst,
        password="P@ssw0rd",
        buffer_size=1024
    ):
        pass
    encrypted_data = dst.getvalue()
    print(encrypted_data.hex())

Feedback 🤩

I'd be happy checking your feedbacks.

Fastify plugins

Amis — Sat, 26 Jun 2021 23:07:59 +0000

Why plugins?
What does a plugin look like?
Encapsulation
How to access registered plugins from route handlers?

Why plugins?

Fastify let you to plug ( inject ) your dependencies to Fastify instance and then use them wherever you have access to the instance throughout you app. And if you decide to migrate from a monolithic structure to microservices later on, it helps you with that, because every plugin could be a service itself.

What does a plugin look like?

A plugin is just a function that takes in fastify and options as inputs.

This is a plugin:

function pluginA(fastify, options, done) {
    // ...
    done()
}

and this is an async plugin:

async function pluginB(fastify, options) {
    // ...
}

and here is how to register them:

import Fastify from 'fastify'

const fastify = Fastify()

fastify
    .register(pluginA)
    .register(pluginB)

Encapsulation

What encapsulation means is that a copy of Fastify instance is passed to the plugin when you register it. So anything you add to ( decorate ) that instance would only be accessible inside the plugin.

import Fastify from 'fastify'

const fastify = Fastify()

fastify
    .register(function pluginA(fastify, options, done) {
        // Add a random number to fastify instance
        fastify.decorate('rand', Math.random())

        console.log(fastify.rand) // Accessible here

        done()
    })
    .register(function pluginB(fastify, options, done) {
        // Try to access the random number added in pluginA
        console.log(fastify.rand) // undefined

        done()
    })

What if you don't want encapsulation? You can use fastify-plugin package to register a plugin to the main Fastify instance.

import Fastify from 'fastify'
import fp from 'fastify-plugin'

const fastify = Fastify()

fastify
    // Register pluginA with fastify-plugin
    .register(fp(function pluginA(fastify, options, done) {
        // Add a random number to fastify instance
        fastify.decorate('rand', Math.random())

        console.log(fastify.rand) // Accessible here

        done()
    }))
    .register(function pluginB(fastify, options, done) {
        // Try to access the random number added in pluginA
        console.log(fastify.rand) // Also accessible here

        done()
    })

Packages like fastify-postgres, fastify-mongodb, fastify-redis, ... they all use fastify-plugin so you won't have to register them with fastify-plugin.

Here is the simplified version of fastify-postgres plugin:

const pg = require('pg')
const fp = require('fastify-plugin')

function fastifyPostgres(fastify, options, next) {
    const pool = new pg.Pool(options)
    const db = {
        connect: pool.connect.bind(pool),
        pool: pool,
        Client: pg.Client,
        query: pool.query.bind(pool),
        transact: transact.bind(pool)
    }
    // Inject postgres connection to Fastify instance
    fastify.decorate('pg', db)
    next()
}

module.exports = fp(fastifyPostgres)

How to access registered plugins from route handlers?

Here I used PostgresSQL. I want to be able to use it inside my route handlers to send queries to the database:

// index.js

import Fastify from 'fastify'
import pg from 'fastify-postgres'
import routes from './routes.js'

const fastify = Fastify()

fastify
    .register(pg, {
        connectionString: 'postgres://postgres@localhost/postgres'
    })
    .register(routes)

Here I defined route handlers inside a plugin, so I can access fastify.pg there:

// routes.js

export default function routes(fastify, options, done) {
    fastify.route({
        method: 'GET',
        url: '/',
        handler: (req, reply) => {
            // Have access to fastify.pg here
        }
    })

    done()
}

Here I defined route handlers in a seperate module, so in order to access fastify I need to use the this keyword.

NOTE: Normal functions must be used rather than arrow functions to define route handlers. Read more here.

// routes.js

import { mainHandler } from './handlers.js'

export default function routes(fastify, options, done) {
    fastify.route({
        method: 'GET',
        url: '/',
        handler: mainHandler
    })

    done()
}

// handlers.js

export function mainHandler(req, reply) {
    // Have access to this.pg here
}

End

I recommend you to read the docs if you still have questions about Fastify plugins. You can also join Fastify discord channel, there is a fantastic community there that can help you out.