This project provides a couple of .NET / C# libraries for cryptographically signing and verifying data using .NET in some advanced scenarios.
As the name CryptoEx suggests, it can be think of both as Extension of and Example of the usage of the standard capabilities provided by the .NET platform in areas like:
- XML digital signatures - XML Signature Syntax and Processing Version 1.1
- JSON digital signatures - JSON Web Signature (JWS)
- EdDsa (Ed25519 and Ed448)
- EdDiffieHellman (X25519 and X448)
- Advanced Electronic Signatures and Infrastructures standardized by the European Union,
so called JAdES & XAdES
- All levels - Baseline-B, Baseline-T, Baseline-LT & Baseline-LTA
CryptoEx and CryptoEx.Ed may be installed from NuGet:
Just write:
dotnet add package CryptoEx
dotnet add package CryptoEx.Edor use your package manager in Visual Studio.
This project does not have an intention to be a full-featured library that fully implements all possible features and applications in all possible scenarios for digital signatures (In my humble opinion it is not feasible option anyway). Rather than that, it's purpose is to be used as a reference (or example if you prefer) of how to achieve some tasks using platform's abilities in some areas and how to extend minor platform's gaps in other areas.
For example in XML signatures area, there is mature (and not very much evolving) library provided by the platform itself - System.Security.Cryptography.Xml, but in my personal experience there are two major issues with it:
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Examples and documentation are messy - You may easily see from Microsoft's docs how to do basic sign / verify of an enveloped XML message, but you will be in trouble finding "official" docs and examples on some more advanced scenarios, like - detached signatures or signing additional Reference XML data.
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The basic library also lacks some algorithms that are part of the XML digital signature specification - namely the ones with EcDSA.
Now this might be annoying flaws, but also they are to some extend either "natural" (the all possible implementations, ways to implement XML signing, is vast area, because of the "openness" of the specification) or easy to overcome. So, in the current project I have extended the standard library to support the missing algorithms and have provided some implementations to show, as an example, how to sign Detached data and additional Reference XML elements.
You can check the code and some pages in the Wiki.
You can freely use it as an example and further amend or extend the code to suit your particular needs as possible applications are vast.
Other example is the JSON Web signatures area. In this domain there are few open source libraries but either their focus is JSON Web Tokens (that are private case of the broader JSON Web Signatures) or they are limited in application for JAdES.
In the current project you can find an implementation of the RFC 7515 (JSON Web Signatures) specification and practical implementation for the European Union's Advanced digital signatures for JSON data specification (JAdES), that builds on top of RFC 7515 (JSON Web Signatures).
Please, check the code and the corresponding Wiki Pages.
Again, you are free and encouraged to use these as an example or to extend these to suit you purposes in a better way.
There is one Visual Studio Solution that summons all .NET projects in the current repository.
The individual .NET projects are:
- CryptoEx - the main project / library of the repository, with core program logic
- CryptoEx.Test - test for the core library
- CryptoEx.Benchmark - Micro-benchmark for the core library
- CryptoEx.Ed - Extension of the logic in the core library to support Ed25519 & Ed448 cryptographic algorithms for digital signatures. Also, to support X25519 & X448 for Diffie-Hellman key agreement.
The main project / library of the repository, with core program logic. Here you can find and if needed extend the logic for main areas - advanced XML signing, JSON web signatures and applications of the above in EU's XAdES and JAdES.
The test for the core library. Has a dependency on xUnit, for testing.
Can be looked at as an example of client programming logic that calls methods from the core library.
The Micro-benchmark for the core library. Has a dependency on BenchmarkDotNet.
Some useful test for speed and memory consumptions. Especially interesting for signing large external files in detached mode - for time and memory allocations.
Also for other micro-benchmarking for example for Base64Url encoding and decoding.
Extension of the logic in the core library (CryptoEx) to support Ed25519 & Ed448 cryptographic algorithms for digital signatures and X25519 & X448 algorithms for Diffie-Hellman key agreement. The project also implements JWSs (JSON Web signatures) and JAdES (Advanced JSON Web Signatures) with EdDSA algorithm.
I have decided to put these on a different project (different from CryptoEx), mainly because Ed25519, Ed448, X25519 & X448 are still not implemented in main-stream .NET. So, I need to rely on third-party libraries, such as:
- Bouncy Castle
- libsodium based wrappers
At the moment I have decided to use Bounty Castle, because it is 100% managed code and it is also performance optimized. The CryptoEx.Ed project has a dependency on Bounty Castle.
The project implements Ed signatures and key-exchanges in an similar to the standard .NET way and it can be used by .NET developers in a familiar way - as EC (Elliptic curves) are being used.
As a practical example of the usage of the Ed classes in the library, I have also extended the classes for JWSs (JSON Web Signatures) and for the JAdES (Advanced JSON Web Signatures) from the core library to implement EdDSA algorithm for them.
You can check the code and some documentation pages in the Wiki, for HOWTOs.