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https://github.com/tleonhardt/practical_cryptography_engineering
Cryptography code examples using libsodium and mbedtls C libraries and Python cryptography and PyNaCl modules
https://github.com/tleonhardt/practical_cryptography_engineering
c cryptography libsodium mbedtls practical python
Last synced: 27 days ago
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Cryptography code examples using libsodium and mbedtls C libraries and Python cryptography and PyNaCl modules
- Host: GitHub
- URL: https://github.com/tleonhardt/practical_cryptography_engineering
- Owner: tleonhardt
- License: apache-2.0
- Created: 2018-02-21T02:17:14.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2019-11-09T17:33:20.000Z (about 5 years ago)
- Last Synced: 2024-11-18T23:51:02.410Z (2 months ago)
- Topics: c, cryptography, libsodium, mbedtls, practical, python
- Language: C
- Homepage:
- Size: 889 KB
- Stars: 71
- Watchers: 9
- Forks: 8
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
Practical Cryptography Engineering
==================================
This repository contains some practical code examples of using the following cryptography libraries:
* [libsodium](https://github.com/jedisct1/libsodium)
* A modern, portable, easy to use crypto library written in C with a small number of high quality primitives
* Focuses on making it easy to use cryptography correctly
* [mbedTLS](https://github.com/ARMmbed/mbedtls)
* An ultra-portable crypto library written in C which should build anywhere
* Provides a wide range of the most common cryptographic primitives and associated infrastructure
* [cryptography](https://github.com/pyca/cryptography)
* Python's "standard" cryptographic library which is a wrapper around [OpenSSL](https://www.openssl.org)
* Provides almost all cryptographic primitives you would want in Python
* [PyNaCl](https://github.com/pyca/pynacl)
* Python bindings for libsodium (very partial wrapper around libsodium)
* Provides a few nice cryptographic primitives not currently available in the cryptography module
File Contents
=============
Build-related and Miscellaneous
-------------------------------
* CMakeLists.txt
* CMake file for building the mbedTLS C code projects
* mbedtls
* Directory containing the mbedTLS C code
* sodium
* Directory containing libsodium examples, headers, and Windows pre-compiled library
* See the Readme.md in this directory for more info on these examples
Symmetric Encryption
--------------------
These code examples use an [AES](https://en.wikipedia.org/wiki/Advanced_Encryption_Standard) block cipher with a 256-bit
key in [Galois Counter Mode](https://en.wikipedia.org/wiki/Galois/Counter_Mode) (GCM). The C code examples use the
mbedTLS library, while the Python examples use the cryptography module.
* aes_gcm.c
* Simple self-contained C code example of using AES-256 in Galois Counter Mode (GCM) using hard-coded everything
* aes_gcm_cryptography.py
* Simple self-contained Python code example identical to the above
* aesgcm_file.c
* C code example of file-based AES-256 GCM, works with aesgcm_file.py
* Takes arguments on command line and produces output to file
* aesgcm_file.py
* Python code example of file-based AES-256 GCM, works with aesgcm_file.c
The following example uses the PyNaCl wrapper around libsodium along with the **SecretBox** authenticated
encryption API.
* nacl_symmetric_gen.py
* Generates a random 256-bit (32-byte) secret symmetric key and saves it to a file
* Then uses it to encrypt a fixed message and verify that it can decrypt it and get the same message
Key Exchange
------------
These code examples use an Elliptic-curve Diffie-Hellman [ECDH](https://en.wikipedia.org/wiki/Elliptic-curve_Diffie–Hellman)
key agreement protocol to establish a shared secret over an insecure channel. The C code examples use the mbedTLS
library, while the Python examples use the cryptography module.
* ecdh.c
* Elliptic Curve Diffie-Hellman key exchange C code example
* ecdh.py
* Elliptic Curve Diffie-Hellman key exchange Python code example
Key Derivation
--------------
These code examples demonstrate how to use a Key Derivation Function [KDF](https://en.wikipedia.org/wiki/Key_derivation_function)
to derive one or more shared keys from a shared secret.
* kdf.c
* Key Derivation Function (KDF) C code example
* kdf.py
* Key Derivation Function (KDF) Python code example
Digital Signatures
------------------
These examples use the PyNaCl wrapper around libsodium to support public-key digital signatures using the Ed25519 algorithm.
* nacl_genkey.py
* Generates a random ed25519 SigningKey/VerifyingKey key pair for use with a digital signature system
* nacl_sign.py
* Uses PyNaCl to sign a message using ed25519 digital signature algorithm
* nacl_verify.py
* Uses PyNaCl to verify an ed25519 signature for a given message
These examples use RSA-PSS digital signatures. The C code examples use the mbedTLS library, while the Python examples
use the cryptography module.
* rsa_signature.c
* RSA Signature C code example
* rsa_signature.py
* RSA Signature Python code example
Building
========
libsodium C examples
--------------------
The [libsodium](https://download.libsodium.org/doc/) C code examples are all in the **sodium** directory and can be
built using the [Cmake](https://cmake.org) cross-platform build tool along with your platform default C compiler
installed on Windows, macOS, or Linux.
The first stage of building is the same on all platforms:
```bash
cd sodium
rm -rf build
mkdir build
cd build
cmake ..
```
The second stage of building is platform dependent and will create the following executable files:
* hello_sodium
* nacl_keygen
* nacl_sign
* nacl_verify
* symmetric_decrypt
* symmetric_encrypt
* symmetric_keygen
* test_ed25519
* test_pynacl_compatibility
### Linux or macOS
```bash
make
```
This produces the executable files directly in the **build** directory.
### Windows
```bash
devenv hello_sodium.sln /build Debug
```
This creates the executable files under the **build\Debug** directory.
Python examples
---------------
The Python examples are located in the root directory and should work with Python 3.4 or newer. The Python examples
require a mix of the following Python packages:
* [cryptography](https://cryptography.io/en/latest/) - high-level wrapper around [OpenSSL](https://www.openssl.org)
* [pynacl](https://pynacl.readthedocs.io/en/stable/) - Python binding to [libsodium](https://libsodium.org)
* [colorama](https://github.com/tartley/colorama) - cross-platform colored terminal text
The required dependencies can easily be installed using [Pipenv](https://github.com/pypa/pipenv):
```shell script
pipenv install
```
Then a shell using the underlying virtual environment can be entered with:
```shell script
pipenv shell
```
Inside that Pipenv shell, any of the examples can be ran directly. e.g.:
```shell script
python ./aes_gcm_cryptography.py
```
The Python examples are intended to interoperate with either the libsodium or mbedTLS C code examples. Thus encryption
or signing can be done in C and decryption or verifying can be done in Python or vice versa.
mbedtls C examples
------------------
The [mbedTLS](https://github.com/ARMmbed/mbedtls) C code examples are located in the root directory and build mbedTLS
from source from the **mbedtls** directory.
Build requires CMake and platform default C compiler installed and works on both Windows, macOS, and Linux.
The first stage of building is the same on all platforms:
```bash
rm -rf build
mkdir build
cd build
cmake ..
```
The second stage of building is platform dependent ...
### Linux or macOS
```bash
make
```
This produces the following executable files directly in the **build** directory:
* aes_gcm
* aesgcm_file
* ecdh
* kdf
* rsa_signature
### Windows
```bash
devenv mbed_AES.sln /build Debug
```
This creates the following executable files under the **build\Debug** directory:
* aes_gcm.exe
* aesgcm_file.exe
* ecdh.exe
* kdf.exe
* rsa_signature.exe
Where to learn more about cryptography
======================================
Books
-----
* [Cryptography Engineering](https://www.amazon.com/Cryptography-Engineering-Principles-Practical-Applications/dp/0470474246)
by Niels Ferguson, Bruce Schneier, and Tadayoshi Kohno
* Extremely well written and easy to understand
* Focuses on the practical aspects that often result in weak crypto when used incorrectly
* Discusses how to build an entire cryptographic system from the ground up
* [Understanding Cryptography](https://www.amazon.com/Understanding-Cryptography-Textbook-Students-Practitioners/dp/3642041000)
by Christof Paar, Jan Pelzl, and Bart Preneel
* Amazing book which makes it relatively easy to teach yourself cryptography
* [Website](http://www.crypto-textbook.com)
* YouTube lecture [videos](https://www.youtube.com/watch?v=2aHkqB2-46k&list=PL6N5qY2nvvJE8X75VkXglSrVhLv1tVcfy)
* [Solutions](http://wiki.crypto.rub.de/Buch/en/download/Understanding_Cryptography_Odd_Solutions.pdf) Manual,
Lecture [Slides](http://wiki.crypto.rub.de/Buch/en/slides.php)
Online Courses
--------------
* [Cryptography I](https://www.coursera.org/learn/crypto)
* Taught by Stanford University professor Dan Boneh
* Available for free on Coursera
* [Applied Cryptography](https://www.udacity.com/course/applied-cryptography--cs387)
* Taught by University of Virginia professor Dave Evans
* Available for free on Udacity
Presentation
------------
This repository includes the following basic intro presentation:
* [Practical Cryptography Engineering](https://github.com/tleonhardt/practical_cryptography_engineering/blob/master/Practical_Cryptography_Engineering.pdf)
Disclaimer
==========
I am not an expert in cryptography. I am just a software developer who wanted to learn more about how to use
cryptography effectively. If anyone looking at this **is** an expert in cryptography and happens to notice any
weaknesses, inaccuracies, or mistakes and/or has constructive feedback for how to improve the examples then Pull
Requests or Issues would be sincerely appreciated.