ansemjo/randomart

generate plaintext pictures from a hash, similar to OpenSSH's keygen randomart

randomart.py

A script to present BLAKE2b hashes as small ASCII-art pictures, similarly to OpenSSH's randomart.

This allows easier verification by humans but may not be as secure as a bytewise comparison of the digest!

See the paper Hash Visualization: a New Technique to improve Real-World Security for more information on the concept of random art.

The paper The drunken bishop: An analysis of the OpenSSH fingerprint visualization algorithm analyses the OpenSSH implementation in more detail.

Just to be clear: the input is passed into a hash function and its output is then used to generate the ASCII art. By virtue of BLAKE2b being a cryptographically secure hash function, any change in input will lead to a radically different output.

It should also be explicitly noted that my algorithm is similar but not identical to the "drunken bishop" walk of the OpenSSH implementation. The implementation at hand:

• flips sides at the borders, which turns the field into a torus
• moves in all possible directions with distance 1, not only diagonally
• does not mark start (S) and end (E) and uses a different character palette

I have not performed any similar analysis[²][^2] but would expect my implementation to perform no worse.

installation

Install the latest version with pip directly from GitHub:

pip install git+https://github.com/ansemjo/randomart

Or from PyPI:

pip install randomart

usage

The script expects a file in the first positional argument or otherwise simply reads from standard input. It is thus best suitable for usage in a pipe:

echo 'Hello, World!' | randomart.py

There are two flags to control the output:

• --ascii use only ASCII characters for the box frame
• --hash - print the computed digest before the randomart picture

Otherwise use randomart.py --help for usage help.

as a library

If you want to use your own hash you can import from random_art.randomart:

from random_art.randomart import draw, drunkenwalk
...

# generate your hash digest
digest = ...

# generate randomart, HASHNAME must be 10 characters
art = draw(drunkenwalk(digest), HASHNAME)
print(art)