emre etherx-dev

20 million digits of pi in under a minute with Julia

I recently discovered a relatively obscure algorithm for calculating the digits of pi: https://en.wikipedia.org/wiki/Gauss–Legendre_algorithm. Well, at least obscure compared to Chudnovsky's. Wikipedia notes that it is "memory-intensive" but is it really? Let's compare to the MPFR pi function:

function gauss_legendre(prec)
    setprecision(BigFloat, prec, base=10)
    GC.enable(false)

Introduction

It would be spiffy to use the balanced merkle forest idea for ethereum tokens or to store unspent transaction outputs.

Tadge Dryja has been working on 'utreexo' (presentation) for storing unspent transaction outputs in log(n) space; this gist is inspired by, and is very similar to, that work.

So my previous gist describes really simple algorithms for adding and removing items from a balanced merkle forest. This gist extends those operations to create

DOGECOIN FEE POLICY CHANGE PROPOSAL

This document proposes a new fee structure and policy for Dogecoin Core, to be gradually deployed to the network over multiple software releases.

Historical fee policy

Meaningful fees were introduced for Dogecoin in 2014 to reduce on-chain spam. With a 1 DOGE fee per kilobyte, rounded up, the Dogecoin chain provided

Hal Finney's explanation of secp256k1 "efficiently computable endomorphism" parameters used secp256k1 libraries, archived from source.

The same optimization could be applied to any Koblitz curve (e.g. Short Weistrass curve with a=0).

I implemented an optimized ECDSA verify for the secp256k1 curve, based on pages 125-129 of the Guide to Elliptic Curve Cryptography, by Hankerson, Menezes and Vanstone. I own the book but I also found a PDF on a Russian site which is more convenient.

secp256k1 uses the following prime for its x and y coordinates:

To Catch a Hacker - NPM Event Stream

(Note: this post is from a legacy blog dated 12/14/2018 and some content or links may have changed)

A few weeks ago, this issue was opened on a popular Node NPM package called Event Stream. This package enables Node streams to be simpler and streamlines many I/O operations within Node. Regardless, this package is a key dependency for many other Node packages and has over 1 million downloads per week from NPM. The newly opened issue initially questioned a new, suspicious dependency that was pushed by a new, unknown maintainer. I was lucky enough to follow the community's investigation into this issue and now, I hope to present the findings here. My goal with this piece is to hopefully shed some light on how easy it is for somebody to inject malicious code into NPM packages, the responsibility of open source maintainers, and the responsibility of the community.

The Malicious Code

A Github user noticed that

	from binance.client import Client
	from binance.exceptions import BinanceAPIException, BinanceRequestException
	#incomplete but i just need a useful regex
	client = Client("apikey", "secret")

	coininfo = client.get_all_coins_info()
	for coin in coininfo:
	for network in (coin['networkList']):
	print(coin['name'],network['addressRegex'])

	# https://www.cloudflare.com/ips
	# https://support.cloudflare.com/hc/en-us/articles/200169166-How-do-I-whitelist-CloudFlare-s-IP-addresses-in-iptables-

	for i in `curl https://www.cloudflare.com/ips-v4`; do iptables -I INPUT -p tcp -m multiport --dports http,https -s $i -j ACCEPT; done
	for i in `curl https://www.cloudflare.com/ips-v6`; do ip6tables -I INPUT -p tcp -m multiport --dports http,https -s $i -j ACCEPT; done

	#include <windows.h>
	#include <stdio.h>
	#include <stdint.h>

	#pragma comment(lib, "USER32")

	FARPROC NtUserPostMessage;

	BOOL CALLBACK QueryWindowMessageProc(HWND Window, LPARAM Param)
	{

	from subprocess import Popen, PIPE, STDOUT
	from multiprocessing import Process, Queue
	import queue
	import os
	import re
	from termcolor import colored
	import argparse
	import time
	from datetime import datetime
	from dataclasses import dataclass

	# First, we need to find our device. BEFORE inserting your USB drive, run the
	# following:
	diskutil list

	# This will output a bunch of info about all of the disk drives connected to
	# your Mac. Each entry will have a header in the form "/dev/diskX", where X is
	# some number starting at 0. Now, insert your USB drive and run the command
	# again. You should see a new entry. Make note of the name (ie, /dev/diskX).
	diskutil list