Signethic

A Python module to easily and quickly cryptographically sign a "thing". The "thing" in question can be anything like a string, or any binary sequence. The binary sequence could be the output of a serializer, pickling, shelving, compiled code, encoder, compression or pretty much anything else. The digital signature based on Public-Key Cryptography Standards (PKCS) prevents tampering.

Note that this is not doing any encryption, only signing. This protects the "thing" from manipulation, but not from reading. Your overall cybersecurity strategy should also cover encryption at rest, encryption in flight and least privileges, along with all the other best practices in this area.

Installation

From source

python setup.py install

From pypi

pip install signethic

Quickstart

Signing a "thing" and saving to a binary file that will contain the digital signature (PKCS) and the "thing". In this case, a string:

from signetic import sign_and_persist


thing = "the result of our campaign #12345 resulted in sales of $54321.00"

signature = sign_and_persist(thing, path="result.signed")

Verifying a file that has been signed, returning the "thing" if the signature is verified:

from signetic import verify_file

public_key = …

thing = verify_file("result.signed", public_key)

Command Line

After installing signethic, a command line is available. With no argument, it will generate a private and public key, create a string, sign it, verify it, save a binary file with the signature and string and verify that file. (see main() for the details of the steps).

Calling signethic with a filename will generate a new file with the .signed extension that includes the signature and the file. It will be signed using the key signing_key.pem in the current directory, by default. To specify a different signing key, use an environment variable:

export SIGNING_KEY=/path/to/key.pem

Requirements

This version uses pycryptodome to provide the pycrypto package. Version is unfrozen, so you can preinstall whichever version of pycryptodome you have validated, and signethic will use that.

For example, to use latest pycryptodome from conda-forge:

conda install -c conda-forge pycryptodome

If you prefer to use the original pycrypto, install version 0.2 (pip install signethic==0.2)