#!/usr/bin/env nix-shell
#!nix-shell -i bash
file="$1"
enc="$2"
nibbles="$3"
echo "$file" | cat /dev/stdin /etc/ssh/host_keys/ssh_host_ed25519_key \
  | sha512sum \
  | cut -c "1-$nibbles" \
  | tr a-z A-Z \
  | basenc -d --base16 \
  | basenc "--$enc" \
  > "$file"