DHCache

Overview

DHCache is a micro Diffie-Hellman parameter generation web service. It provides a lightweight and efficient way to concurrently pre-generate and maintain an ephemeral cache of unique DH parameters in various sizes for secure key exchange operations.

Features

• Concurrent Pre-Generation of Diffie-Hellman parameters
• Ephemeral Caching to securely minimize delays
• RESTful API to retrieve and evict cached parameters
• Configurable Key Sizes and Parameter Counts at runtime
• Lightweight and Fast implementation in Rust

Installation

Prerequisites

• Rust (latest stable version recommended)
• Cargo (Rust package manager)

Install Using Cargo

DHCache is available on crates.io, and can be installed using cargo:

cargo install dhcache

Install Using Git

If you prefer to experiment with the latest version from the source repository, you can directly clone and build it manually.

# Clone the repository
git clone https://github.com/brianewell/dhcache.git
cd dhcache

# Optionally run tests
cargo test

# Build the project
cargo build --release

# Run the service
./target/release/dhcache

Configuration

All configuration is performed through command-line parameters, available by calling the program with the --help flag:

dhcache --help
A micro Diffie-Hellman parameter generation web service

Usage: dhcache [OPTIONS] <count>:<bits>...

Arguments:
  <count>:<bits>...

Options:
  -b, --bind <address>     [default: 0.0.0.0]
  -p, --port <port>        [default: 4000]
  -w, --workers <workers>  [default: 1]
  -h, --help               Print help
  -V, --version            Print version

The listening address, port, and worker count have configurable defaults. The cache behavior is defined by a collection of <count>:<bits> pairs, where <count> represents the number of DH parameters of size <bits> to cache.

The following command starts DHCache on its default listening address, port 80, and uses two worker threads to maintain a cache of eight 1024-bit DH parameters, four 2048-bit DH parameters, and two 4096-bit DH parameters:

dhcache -w 2 8:1024 4:2048 2:4096

Usage

All interactions with DHCache occur via the configured web service.

List Available DH Parameters

GET /
GET /status

Returns the overall status of the cache.

• Parameters: None
• Response:
  • HTTP 200: Returns a JSON-encoded response listing DH parameters, including their bit sizes, relative paths, available parameters, and the maximum number of parameters cached.

Example Response:

{
  "1024": {
    "path": "/1024",
    "available": 6,
    "max": 8
  },
  "2048": {
    "path": "/2048",
    "available": 4,
    "max": 4
  },
  "4096": {
    "path": "/4096",
    "available": 2,
    "max": 2
  }
}

Retrieve DH Parameters

GET /<bits>

Returns a set of DH parameters.

• Parameters:
  • <bits> (integer): Specifies the key size of DH parameters to retrieve from the cache.
• Response:
  • HTTP 200 (OK): Returns a JSON-encoded response containing the requested DH parameters.
  • HTTP 404 (Not Found): The requested bit size is not configured in the cache.
  • HTTP 503 (Service Unavailable): The requested bit size is supported, but no parameters are currently available.

Evict Cached Parameters

DELETE /<bits>

Clears and regenerates all DH parameters for a given size.

• Parameters:
  • <bits> (integer): Specifies the key size of DH parameters to clear from the cache.
• Response:
  • HTTP 204: The request was successfully processed.
  • HTTP 404: The specified bit size is not configured for caching.

Contributing

Contributions are welcome! Please open an issue or submit a pull request to improve DHCache.

License

This project is licensed under the MIT License. See LICENSE for details.

Contact

For questions or issues, feel free to open an issue on GitHub.