Ben benjiqq

In reply to "@Vlad_Roberto: No, not a programmer. I just know there's better ways to doing anything without massive energy consumption & Banks."

The problem of blockchain synchronization is the following:

Imagine you are sitting in a bunker. You have no idea what people are out there and what are their intentions. You only receive some incoming messages from strangers that may contain anything. They can be just random garbage or deliberately crafted messages to confuse you or lie to you. You never know. You cannot trust anyone.e

The problem of "money" or any other "social contract" is that everyone should be able to know what the majority agrees to without trusting some intermediaries (otherwise they can easily obuse their special position). If everyone votes for "X", then you sitting in a bunker must somehow independently figure out that all those other people indeed voted for "X" and not for "Y" or "Z". But remember: you cannot trust anyone's message and messages are the only thing you get from the outsi

Abstract:

The current derivation method of Hierarchical Deterministic wallets has a weakness in which any individual private key may be combined with any ancestor extended public key (as long as there are no hardened keys in between) to generate the associated extended private key.

This proposal will set out to eliminate this weakness by:

1. Using 1 leak protection of keys
1. Using convention to prevent multiple keys being derived from the same parent.

Motivation:

There is a lot of considerations for security in use cases that would benefit from an extended public key on a server to generate public keys. Currently there are even certain business models that are impossible to use BIP32 due to the weakness.

O(1) Block Propagation

The problem

Bitcoin miners want their newly-found blocks to propagate across the network as quickly as possible, because every millisecond of delay increases the chances that another block, found at about the same time, wins the "block race."

Crypto Review of Curve25519.java & Crypto.java

By DoctorEvil on Nextcoin.org

Sponsored by MSIN on BitcoinTalk.org

TL;DR

NXT's Crypto.java and Curve25519.java look kosher aside from a signing bug that is currently being worked around.

	#!/usr/bin/env ruby
	require 'open-uri'
	require 'JSON'
	require 'digest/sha2'
	require 'pry'
	require 'bigdecimal'
	require 'bitcoin' # Because I need to cheat every now and then

	# Usage:
	# gem install pry json ffi ruby-bitcoin

	from pycoin.tx.pay_to import address_for_pay_to_script, build_hash160_lookup, build_p2sh_lookup, ScriptMultisig
	from pycoin.key import Key

	def generate_multisig_address(priv_keys, N=3, M=2, netcode = COIN_NETWORK):
	'''
	Generate a multisig address from a list of pycoin keys (addresses public or private)
	multisig N out of M
	'''
	#keys = sorted(keys, key=lambda k: k.sec_as_hex()) #sort keys to have the same multisig address from any similar list of keys
	keys = []

	import zmq

	def main():
	try:
	context = zmq.Context(1)

	frontend = context.socket(zmq.SUB)
	frontend.bind('tcp://*:5559')
	frontend.setsockopt(zmq.SUBSCRIBE, '')

	// see build.gradle for imports
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;
	import ch.qos.logback.classic.LoggerContext;
	import ch.qos.logback.core.util.StatusPrinter;
	...
	public abstract class Utilities {
	public static final Logger logger = LoggerFactory.getLogger( "AnyUniqueStringHere" );
	...
	public static void printLoggerState() {

	# a pedagogical implementation of curve25519 with ec-kcdsa
	# coded by doctorevil to validate nxt's port of Matthijs van Duin's implementation
	# warning: this implementation is not timing attack resistant
	# ec arithmetic equations from http://hyperelliptic.org/EFD/g1p/auto-montgom.html

	from hashlib import sha256
	from ecdsa.numbertheory import square_root_mod_prime, SquareRootError, inverse_mod

	CURVE_P = 2**255 - 19
	CURVE_A = 486662

	"""
	Bridge test client:

	So this one's going to be a doozy.

	Connect to target via SSH and then connect to target:localhost:8283(DAVE) and listen
	for the time messages.

	"""