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Reverse Engineered VAS Protocol Specification

Research by Grayson Martin
Last Updated 7/8/23

Introduction

Value Added Services (VAS) is the protocol used by NFC capable passes in Apple Wallet. Access to this protocol is heavily restricted on both the device end (a special certificate issued by Apple is required to create these passes) and the reader end (NDA enforced confidentiality). As such, a desire arose to better understand the protocol in order to explore additional use cases and examine its cryptographic integrity. There are gaps in understanding in certain parts of this protocol, however this document contains the minimum necessary understanding to automatically select, read data from, and decrypt a pass.

Importantly, this specification does not enable a malicious actor to read the data from a pass for which they do not have both the reader's private key, and the pass type identifier. Imp

Configuring httpd (apache2) and php 7.2 in Mac using Homebrew

# 0. Disable built-in Apache
sudo apachectl stop
sudo launchctl unload -w /System/Library/LaunchDaemons/org.apache.httpd.plist 2>/dev/null

# 1. Install httpd
brew install httpd

Ubuntu-Server-Hardening

1. Secure Shared Memory

What is shared memory?

Shared memory is an efficient means of passing data between programs. Because two or more processes can use the same memory space, it has been discovered that, since shared memory is, by default, mounted as read/write, the /run/shm space can be easily exploited. That translates to a weakened state of security.

If you’re unaware, shared memory can be used in an attack against a running service. Because of this, you’ll want to secure that portion of system memory.

Finding shapes in Tex mobjects

This module implements some utility functions to search some shapes (formulas, symbols) inside a Tex (or MathTex) mobject.

The approach is to compare the shapes (bezier curves) of the symbols, instead of the particular strings that produced them. This approach is generic and avoids the use of other manim mechanisms that would break under some circunstances, such as the presence of \frac{}{} in a formula.

The function you would probably want to use is group_shapes_in_tex(). Despite the confusing name, the goal is to find all the occurences of a given symbol (or group of symbols, or list of symbols) inside a Tex mobject, and return a VGroup containing them

A curated list of command-line utilities written in Rust

Note: I have moved this list to a proper repository. I'll leave this gist up, but it won't be updated. To submit an idea, open a PR on the repo.

Note that I have not tried all of these personally, and cannot and do not vouch for all of the tools listed here. In most cases, the descriptions here are copied directly from their code repos. Some may have been abandoned. Investigate before installing/using.

The ones I use regularly include: bat, dust, fd, fend, hyperfine, miniserve, ripgrep, just, cargo-audit and cargo-wipe.

atuin: "Magical shell history"
bandwhich: Terminal bandwidth utilization tool

LMC Fibonacci Generator

You can run this program on any LMC emulator, such as http://peterhigginson.co.uk/LMC/

LMC, which stands for Little Man Computer is a model of a computer, used to teach students how CPUs work. Read More.

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Which GGUF is right for me? (Opinionated)

Good question! I am collecting human data on how quantization affects outputs. See here for more information: ggerganov/llama.cpp#5962

In the meantime, use the largest that fully fits in your GPU. If you can comfortably fit Q4_K_S, try using a model with more parameters.

llama.cpp feature matrix

See the wiki upstream: https://github.com/ggerganov/llama.cpp/wiki/Feature-matrix

	let
	nixbuildDomain = "eu.nixbuild.net";
	nixbuildKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPIQCZc54poJ8vqawd8TraNryQeJnvH1eLpIDgbiqymM";
	nixbuildPlatforms = [ "x86_64-linux" "aarch64-linux" ];
	nixbuildFeatures = [ "big-parallel" "benchmark" "kvm" "nixos-test" ];
	nixbuildSSH = ''
	Host eu.nixbuild.net
	PubkeyAcceptedKeyTypes ssh-ed25519
	ServerAliveInterval 60
	IPQoS throughput

	Visual Studio 2022
	Enterprise :
	VHF9H-NXBBB-638P6-6JHCY-88JWH

	Professional:
	TD244-P4NB7-YQ6XK-Y8MMM-YWV2J

	[loggers]
	keys=root,app,uvicorn

	[handlers]
	keys=console,file,uvicorn

	[formatters]
	keys=console,file

	[logger_root]