Asim Ihsan asimihsan

References:

https://qiita.com/que9/items/28a9f7978fd34a620193
https://github.com/pyenv/pyenv/issues/1066#issuecomment-630939869
https://github.com/pyenv/pyenv/issues/2042#issuecomment-1131463276
https://stackoverflow.com/questions/51551557/pyenv-build-failed-installing-python-on-macos

The error:

Chess Training

My current goals:

Go through my checklist before EVERY move.

Stop playing hope chess: if you can find a single weakness in an idea, abandon it and find a new idea.

The Checklist

Introduction

Format Preserving Encryption (FPE) seems to have been invented principally to encrypt credit card numbers into something that looks like a credit card number. Effectively, FPE is a permutation over the domain of the input.

It seems like the main reason is legacy: a lot of databases where created with size and alphabet restrictions on the field of credit card numbers, other systems and applications were probably built to deal with similar restrictions in order to process or transport these credit card numbers. Since it was deemed (I'm guessing) too costly to improve things so that a ciphertext, an IV and an authentication tag could have been stored in there instead; instead rich banks threw money at the problem and cryptographers took the bait.

It seems like there are three ways to do it:

Prefix. Your input domain is very small: write the permutation yourself (01 => 10, 00 => 11, etc.). If you don't have imagination, use AES to encrypt your input domain, and truncate. Hopefully it crea

Falsehoods programmers believe about time

This is a compiled list of falsehoods programmers tend to believe about working with time.

Don't re-invent a date time library yourself. If you think you understand everything about time, you're probably doing it wrong.

Falsehoods

There are always 24 hours in a day.
February is always 28 days long.
Any 24-hour period will always begin and end in the same day (or week, or month).

Gradle, Java plugin, Jar MANIFEST, Class-Path is empty

I struggled with with the jar MANIFEST file built with Gradle containing an empty Class-Path. I traced down the problem to the order of the dependencies and jar blocks in the build.gradle file:

Wrong (jar before dependencies):

jar {
    manifest.attributes(

	Latency Comparison Numbers
	--------------------------
	L1 cache reference/hit 1.5 ns 4 cycles
	Floating-point add/mult/FMA operation 1.5 ns 4 cycles
	L2 cache reference/hit 5 ns 12 ~ 17 cycles
	Branch mispredict 6 ns 15 ~ 20 cycles
	L3 cache hit (unshared cache line) 16 ns 42 cycles
	L3 cache hit (shared line in another core) 25 ns 65 cycles
	Mutex lock/unlock 25 ns
	L3 cache hit (modified in another core) 29 ns 75 cycles

	import sys
	import os

	from fcntl import LOCK_EX
	from fcntl import LOCK_NB
	from fcntl import flock
	from time import sleep

	NO_BLOCK = 'nb'
	BLOCK = 'block'

	#!/usr/bin/env bash
	version="1.5.10"
	pcre_version="8.34"

	set -e

	rm -rf nginx-$version*

	# download nginx

	@echo off
	FOR /f "tokens=*" %%i IN ('docker ps -aq') DO docker rm %%i
	FOR /f "tokens=*" %%i IN ('docker images --format "{{.ID}}"') DO docker rmi %%i