Hashvis

A Rust application for deterministic generation of images.

Hashvis is a small Rust application and library for generating very psychedelic images from an input string. The images are generated in a deterministic manner such that the same input string should always result in the same image being generated.

Hashvis is inspired by OpenSSH's VisualHostKey where the OpenSSH client will display a deterministic piece of ASCII art generated from the host keys when you are trying to authenticate with a remote server. The idea behind this feature is that humans have an easier way to remember visual impressions than long, hex-encoded, fingerprints.

Example usage could be:

• OpenSSH host keys (like with VisualHostKey described above).
• OpenPGP public key fingerprints.
• Tor onion and next-generation onion public keys.

Currently Hashvis takes the user input string and passes it to the SHA3-256 hash function and uses this hash value to seed the ChaCha random number generator. The random number generator is then used to generate a lot of 64-bit floating-point values that are used to generate the expressions that is finally used to plot the RGB image.

Building Hashvis

To download and build Hashvis:

$ git clone https://github.com/ahf/hashvis.git
$ cd hashvis
$ cargo build

You can try running the application using:

$ cargo run --bin hashvis misc/examples/yourusername.png yourusername 256
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/hashvis misc/examples/yourusername.png yourusername`
Generating image with SHA3("yourusername") in misc/examples/yourusername.png ...
R: f(x, y) = cos(pi * sin(pi * cos(pi * tan(pi * sin(pi * sin(pi * y) * y)) * y)))
G: f(x, y) = tan(pi * tan(pi * cos(pi * x * tan(pi * y) * x * x)) * tan(pi * sin(pi * sin(pi * x) * sin(pi * y))))
B: f(x, y) = tan(pi * x)

Feel free to submit a pull request if you think your generated image looks spectacular.

Testing Hashvis

To run the minimal test suite:

$ cargo test

Zooming In and Out

The factor argument that the Hashvis binary takes as an input allows you to zoom in and out. A value smaller than 1.0 will zoom in, and anything larger than 1.0 will zoom out of the normal view port. The default value is 1.0.

Authors

• Alexander Færøy (ahf@0x90.dk).

Interactive Twitter Bot

Matthew Garrett (@mjg59) wrote a very cool interactive Twitter bot which fetches your Github SSH Public Key and executes Hashvis on the first key and tweets out the generated picture.

You can write your Github username to the bot and it will tweet out your, hopefully very unique, picture.

Check out the bot at https://twitter.com/github_idbot

Gallery