Jose Storopoli storopoli

Covenants with CAT and ECDSA

In his article, CAT and Schnorr Tricks I, Andrew Poelstra showed how to emulate OP_CHECKSIGFROMSTACK-like covenants using only OP_CATand Schnorr signatures.

Here, we show that a similar trick is possible to emulate covenants using only OP_CAT and ECDSA signatures.

The High-Level Idea

Recall the ECDSA Signature Equation

Modify /etc/nginx/nginx.conf file
Modify /etc/nginx/sites-available/site.conf file
Create /etc/nginx/useragent.rule file

Where to find user agent strings?
https://explore.whatismybrowser.com/useragents/explore/software_name/facebook-bot/

Looking for same but for Apache2? Here: https://techexpert.tips/apache/apache-blocking-bad-bots-crawlers/

Automating Daily Reports, because fuck it, really...

Each day at our company, developers are required to document their activities, painstakingly jotting down their daily work and future plans. A monotonous chore that I just really dislike.

So now, there's a scribe for that :

Code

Overview

How to configure FreeBSD and applicable applications to work with Yubikey for authentication. This serves as my work-in-progress documentation of the configuration knobs needed to make this work properly.

FreeBSD ssh with piv smartcard slot on Yubikey (pkcs11 via libykcs11.so)
FreeBSD ssh with fido support on Yubikey
FreeBSD Firefox/Chromium with fido + webauthn support on Yubikey
FreeBSD local console and gdm authentication using pam on Yubikey
FreeBSD official YubiKey tools

Latest Tested FreeBSD versions

FreeBSD 13.2 Testing (Aug 2023)
FreeBSD stable/13 Testing (Aug 2023) with OpenSSH_9.3p2

Native wayland support is now working consistently for me in VSCode, giving much better text rendering. Unfortunately, it's still hidden behind some command-line flags.

By adding some files to /usr/local/*, you can ensure that VSCode always launches with these flags.

Adding launch flags to VSCode

Assuming that the VSCode launcher is /usr/bin/code-oss (as is the case in Arch):

Create /usr/local/bin/code-oss with the following content:

9Barista Coffee

120mL Water
18g Coffee
Tamping — firm push downwards — around 5kg of force is enough
Medium to High Heat — closest to 3in in diameter
Expresso should be 35-40mL
Pour your espresso straight away

Grinder

Arch Linux ARM on Crostini

I got Arch Linux ARM installed on a Lenovo Chromebook Duet! I mostly used the instructions from the Arch Wiki as reference.

	#! /usr/bin/env bash

	usage() {
	echo "
	Bind/unbind a USB device from a given vendor:product id
	Usage: $(basename "${BASH_SOURCE[0]}") [-h] [-d\|--dry-run] [--hdmi\|microsd\|usba\|ssd250] [--detect=deviceid:vendorid] [on\|off]

	Example usage: $(basename "${BASH_SOURCE[0]}") --hdmi off
	Example usage: $(basename "${BASH_SOURCE[0]}") --detect=27c6:609c
	" >&2

	#!/usr/bin/env bash
	set -e # Exit on error

	if [ "$EUID" -ne 0 ]; then
	echo "To ensure correct permissions, this script must be run as root."
	exit 1
	fi

	install_location="/var/lib/safing-portmaster" # Must not include trailing slash

	#!/usr/bin/env julia

	function ts_to_s(ts::AbstractString)
	secs = tryparse(Float64, ts)
	if secs !== nothing
	return secs
	end
	hours, mins, secs = parse.(Float64, split(ts, ':'))
	return (hours * 60 * 60) + (mins * 60) + secs
	end