noscrypt

A compact, C90 cross-platform, cryptography library built specifically for nostr

What is noscrypt?

A high-level C utility library built specifically for nostr cryptography operations such as those defined in NIP-01 and the new NIP-44. It was designed to simplify the operations that the secp256k1 library was used for, along with data encryption for the new sepc. It is also being built embedded in mind.

API Example:

NCValidateSecretKey()
NCGetPublicKey()
NCSignData()
NCVerifyData()
NCEncrypt()
NCDecrypt()
NCComputeMac()
NCVerifyMac()
... extended functions

Motivation

At the time of building this project I have not come across any C-only libraries that exposed functionality for nostr specific cryptography. IMO it is easy to use the secp256k1 library incorrectly. In the process of building NVault NIP-44 came out in December and I realized my libraries were falling short for my needs for proper and safe nostr cryptographic operations, and I needed to start over and start with a good base that has all the basic functionality built with trusted and tested libraries.

I wanted a compact and efficient utility library that was portable across systems and runtimes. I will primarily be using this library in a .NET environment, but would like to make a hardware signer sometime.

Testing

Testing is an will be important to a cryptography library, I take that responsibility seriously. There are some basic api validation and correctness tests that can be built into an executable called nctest. Full automated testing suite is done in C# interop as part of my NVault package. This includes testing against the official nip44 vector file. I'm very dependency adverse so native C90 testing using only stdlibs can get gross in a hurry. It will likely happen in the future but not right now.

Hardness

Time sensitive verification always uses fixed time comparison
No explicit/dynamic memory allocations
Public API function input validation is on by default
All stack allocated structures are securely zeroed before return
Stack protection is enabled by default for GCC and MSVC compilers
Schnorr signatures are validated before the signing function returns
Carefully selected, widley used, tested, and audited dependencies

Platform Support

The following table lists the supported platforms and cryptography libraries that noscrypt supports. This will expand in the future. You are free to choose and specify the location of these libraries if you desire during build time, otherwise safe defaults are attempted on your platform.

Arch	Support	Notes	Tested
Windows	OpenSSL (3.0), Mbed-TLS, BCrypt	NT 6.1 +	✅
Linux	OpenSSL (3.0), Mbed-TLS	GCC only	✅
FreeBSD	OpenSSL (3.0), Mbed-TLS	GCC Only

Getting started

GitHub is simply a mirror for my projects. Extended documentation, pre-compiled binaries and source code bundles are always available on my website, along with PGP signatures and checksums.

Documentation
Signed builds and sourcecode

Getting the package

There are 3 ways to get the source code to build this project.
1. Download the signed noscrypt-src.tgz package from my website above (recommended) 2. Clone the GitHub repo git clone https://github.com/VnUgE/noscrypt.git
3. Download a github archive or release when they are available

Building

The following build commands may be incomplete. Please read documentation (link above) for all custom build configurations and tips.

Using CMake

cmake -S . -Bbuild/ -DCMAKE_BUILD_TYPE=Release

Enable built-in tests and debug mode

cmake -S . -Bbuild/test -DCMAKE_BUILD_TYPE=Debug -DNC_BUILD_TESTS=ON

Specify the crypto library

cmake -S . -Bbuild/ -DCMAKE_BUILD_TYPE=Release -DCRYPTO_LIB=<openssl | mbedtls | bcrypt>

Install library globally

cmake --install build/

Using Task

A Taskfile file is included for easy building if you wish to build in easy mode! Use the task --list to see all available commands. The default command task will build the library locally in release mode using defaults.

task

Build in debug mode with tests enabled

task build-debug

Build in debug mode, with testing enabled, then runs the test executable after it's built

task test

Install globally. Run after running the default task or build-debug task

task install

Task accepts any extra arguments following -- and passes them to the cmake build command.
Example:

task <command> -- -DCMAKE_X_X=x

Notes

Builds

Build packages on my website are "manual" I use an internal tool called vnbuild that just does the work of preparing a package, but I have to run it myself.

Branches

There are currently 2 branches I use because of my build process. develop and master. All changes happen in develop, then are merged to master when I feel like they are stable enough. After some testing and time, a tag and release will become available.