Purrito Bin (=♡ᆺ♡=)

ultra fast, minimalistic, encrypted command line paste-bin

Features and Highlights

• Very lightweight: 2-3 MB of RAM on average.
• Listen on multiple address/port combinations, both IPv4 and IPv6.
• Configurable paste size limit.
• Paste storage in plain text, easy to integrate with all web servers (Apache, Nginx, etc.).
• Encrypted pasting similar to PrivateBin.
• Optional https support for secure communication.
• Tiny code base, less than 700 lines of code, for very easy auditing.
• Well documented, man purrito.

docker （ฅ＾・ﻌ・＾）ฅ

Parameters

The docker image allows passing the following variables to configure PurritoBin:

Examples

For all examples below, remember to substitute the value of DOMAIN from localhost to the actual domain/IP of the machine.

PurritoBin listens on port 42069 by default.

docker cli

HTTP

A simple example:

• Run the server while listening for pastes on port 8080
  • Map host port 8080 to container port 42069
• Create a persistent store of pastes in host folder /data/apps/purritobin
  • Make a shared volume by mounting /data/apps/purritobin to /var/www/purritobin inside the container

docker run -d \
  --name=purritobin \
  -p 8080:42069 \
  -v /data/apps/purritobin:/var/www/purritobin \
  --restart unless-stopped \
  purritobin/purritobin

To do a test paste to the above server

  $ echo "cool paste" | curl --silent --data-binary "@${1:-/dev/stdin}" "http://localhost:42069/"
  http://localhost:42069/purr1t0
  $ curl --silent http://localhost:42069/purr1t0
  cool paste

HTTPS

To run with https, the public and private keys need to be provided to the container and mounted at /etc/purritobin.
By default, it is assumed that the public and private keys are stored at /etc/purritobin/public.crt and /etc/purritobin/private.crt, respectively.
For example, assuming that the certificates, for the domain localhost, are stored on the host machine at /data/apps/certificates/{public,private}.crt, PurritoBin can be started in https mode with:

docker run -d \
  --name=purritobin \
  -e DOMAIN="https://localhost:42069/" \
  -e MAXPASTESIZE=65536 \
  -e SLUGSIZE="7" \
  -e TLS="YES" \
  -e PUBLICKEY="/etc/purritobin/public.crt" \
  -e PRIVATEKEY="/etc/purritobin/private.crt \
  -e SERVERNAME="localhost" \
  -p 8080:42069 \
  -v /data/apps/purritobin/:/var/www/purritobin \
  -v /data/apps/certificates:/etc/purritobin \
  --restart unless-stopped \
  purritobin/purritobin

Manual setup （ฅ＾・ﻌ・＾）ฅ

Requirements

• uSockets
• uWebSockets

If these are not available in your OS repositories, you can manually install them by following the steps in the GitHub workflow

Compilation

$ make
$ make install

or to install to a different location, use the DESTDIR or PREFIX variables.

Usage

The server is run using the command purrito. To quickly view the available options:

$ purrito -h
usage: purrito [-acdefghiklmnpstvwx] -d domain [-a slug_characters]
               [-c public_cert_file] [-e dhparams_file] [-f index_file]
               [-g slug_size] [-h] [-i bind_ip] [-k private_key_file] [-l]
               [-m max_paste_size] [-n server name] [-p bind_port]
               [-s storage_directory] [-t] [-v header_value] [-w passphrase]
               [-x header]

For an indepth explanation, there is a man page provided.

$ man purrito

Running the encrypted PurritoBin

Make sure that whatever link is provided to the -d domain option, is also able to serve the paste.html from this repository.

Client (=｀ﻌ´=)

Shell client definitions

Define these functions somewhere in the dot files of your shell (works on all POSIX compliant shells).

: ${P_SERVER=bsd.ac}
: ${P_PORT=42069}
: ${P_MAXTIME=30}

# POSIX shell client to upload standard message
purr() {
	curl --silent --max-time "${P_MAXTIME}" --data-binary "@${1:-/dev/stdin}" "${P_SERVER}:${P_PORT}"
}

# POSIX shell client to upload encrypted message
meow() {
	# we need to generate a 256 byte random key
	# for using the aes-256-cbc cipher
	key="$(openssl rand -hex 32)"
	iv="$(openssl rand -hex 16)"
	# calculate its encryption and upload it
	url="$(openssl enc -aes-256-cbc -K ${key} -iv ${iv} -e -base64 -A < ${1:-/dev/stdin} | purr)"
	printf %s\\n "${url%\/*}/paste.html#${url##*\/}_${key}_${iv}"
	unset key iv url
}

# POSIX shell client to decrypt the message
meowd() {
	url="$1"
	baseurl="${url%\/*}"
	vals="${url##*\#}"
	paste=$(printf %s\\n "${vals}" | cut -d'_' -f1)
	key=$(printf %s\\n "${vals}" | cut -d'_' -f2)
	iv=$(printf %s\\n "${vals}" | cut -d'_' -f3)
	curl --max-time "${P_MAXTIME}" --write-out "\n" --silent "${baseurl}/${paste}" | openssl enc -aes-256-cbc -base64 -d -K ${key} -iv ${iv}
	unset url baseurl vals paste key iv
}

Client usage

You can paste the stdout from a command, paste a file or paste while taking input from a file or from the command line.

    ~$ purr c00lfile.txt
    https://bsd.ac/purrit0

    ~$ purr < h0tfile.txt
    https://bsd.ac/purri1o

    ~$ echo Hello world. | purr
    https://bsd.ac/d4nklit

    ~$ purr
    This is my input
    it can span multiple lines
    <Ctrl-d to exit>
    https://bsd.ac/curlpr0

Encrypted Storage Clients (=｀ᆺ├┬┴┬┴

In a encrypted storage setting, the paste is encrypted before sending it to the server. Now the server will only be used as a storage bin and even in case of a non-https connection, you are guaranteed that no one else will be able to read the data that you have sent.

How does it work?

Steps automatically done by the provided clients, on the client side:

• Randomly generate an ecryption key and initialization vector iv.
• Encrypt your data using said key and iv, the encrypted data is called the cipher.
• Send the cipher to the pastebin and get a standard paste url as above, which will be converted to the form

https://bsd.ac/paste.html#pasteID_key_iv

The standard client is meow, a companion to the above purr, which is also POSIX compliant and should work in all shells. It has exactly the same usage as purr, so please look at those examples to see how to use it. The only dependency on the client side is the presence of LibreSSL or OpenSSL, to do the encryption.

There will be other clients in the clients folder, added on demand for other platforms, which will allow you to do all this automatically. Pull requests for other clients are highly welcome.

Why is this secure?

• All the encryption is done on the client side.
• Only the cipher is sent to PurritoBin.
• The url only contains the encrypted cipher and has no knowledge of the actual data.
• When you visit the html webpage the key is in the hash property of the webpage, which is never sent to the server.
• All decryption is done inside the browser, using javascript, Crypto JS on the client side.

NOTE: Anyone who has the full link is going to be able to read the decrypted text. Only send the full hash included url to people you trust, through a secure communications channel.

Design principles

The aim is to follow the KISS philosophy and only aim to do one thing. There are tools which manage to do the other things better, so make the current one as integrable as possible.

Purrito Bin is very, very easily integrated into any setup. It runs as an unprivileged user in a single directory without access to any other systems resource.

In OpenBSD, it is automatically pledges and unveils the bare minimum to function, so even in the case of a bug in the code, an attacker has no access to the system.

Pull requests to harden the code by default in linux and other operating systems are highly welcome.

What PurritoBin provides

• Auto slug generation and returning paste url.
• Efficient limiting of paste size by cutting off requests at threshold, stopping network blockage.
• Submission port for users to submit.
• Tiny server to browse the pastes. It is optimized for small paste sizes. If accepting really large paste, it is recommended to not use this and instead use a dedicated web server, such as httpd(8), apache, nginx or literally any other web server.
• You can run it on an internal system so that it is accessible only by the people inside the network.

What PurritoBin does NOT provide (yet)

• Auto cleaning of pastes
  • It is possible to use a cron job to manage this.
• Request throttling
  • Use a firewall, like pf, nftables or (god forbid) iptables, to manage this, they are designed for exactly this kind of feature.

Extras

System services

The services directory consists of OpenRC and SystemD service files. They need the purritobin user and group to exist.

Pure C client

ericonr has made a very nice C client, which also supports encrypted pastes - https://github.com/ericonr/purr-c It uses BearSSL and is very instructive for all who wish to get a small example of using SSL in C together with networking.

Credits

uNetworking: for their uWebSockets and uSockets brix: for their crypto-js solusipse: for their fiche pastebin