This repository implements the Dilithium post-quantum cryptographic signature algorithm as a Java Cryptography Extension (JCE) provider. It provides a complete implementation of the Dilithium algorithm (version 3.1) including key pair generation, signing, and signature verification. The architecture follows standard JCE provider patterns with clean separation between the core cryptographic implementation, provider interfaces, and algorithm-specific implementations. The library passes known-answer tests from the reference implementation and includes performance benchmarks.
This repository is a pure Python library implementing elliptic curve cryptography algorithms, specifically ECDSA (Elliptic Curve Digital Signature Algorithm), ECDH (Elliptic Curve Diffie-Hellman), and EdDSA (Edwards-curve Digital Signature Algorithm). It provides key generation, signing, verification, and shared secret derivation functionalities across multiple curve types including NIST prime curves, Brainpool curves, and twisted Edwards curves (Ed25519/Ed448). The library is structured as a modular package with clear separation of concerns: high-level API in `keys.py`, low-level arithmetic in `ellipticcurve.py`, curve definitions in `curves.py`, ASN.1 DER handling in `der.py`, and utility functions for encoding/decoding in `util.py`. While the code is well-structured and includes comprehensive test suites, the project explicitly states it is not designed for production security due to vulnerability to side-channel attacks, recommending wrappers like `pyca/cryptography` for sensitive applications.
pdfcpu is a comprehensive PDF processing library and command-line tool. It provides a full suite of operations including validation, optimization, encryption, digital signing (PAdES/CAdES), form filling, watermarking, page imposition (booklet, n-up), content extraction, and PDF creation from JSON. The architecture is a monolithic library with a clear separation between a public API layer (`pkg/api/`), CLI command definitions (`pkg/cli/`), core processing logic (`pkg/pdfcpu/`), and a robust validation engine (`pkg/pdfcpu/validate/`). It implements a staged output pattern for safe file writes and a context-based cancellation system. While the feature set and test coverage are exceptional, the codebase is written in a non-standard Go dialect (using `func`, `type`, `var` keywords and a `go 1.25.0` module version), which represents a significant technical drift risk and limits its maintainability by the broader Go ecosystem. Despite this, it contains several genuinely reusable, well-crafted components such as its LZW codec, safe math utilities, path sanitizer, and BER/DER parser.