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Fast Multiparty Threshold ECDSA with Fast Trustless Setup

Steven Goldfeder

Digital signatures authorize transactions in cryptocurrencies

• Alice's device, containing her private key, is a single point of failure

Multiparty authentication

• Instead of having a single device store your key material...
  • You can split it into multiple devices

• Designed your address as protected by multiple keys

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Locate the section for your github remote in the .git/config file. It looks like this:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = git@github.com:joyent/node.git

Now add the line fetch = +refs/pull/*/head:refs/remotes/origin/pr/* to this section. Obviously, change the github url to match your project's URL. It ends up looking like this:

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Schnorr signature test vectors

Test vector overview

1. Hash function H(m) = SHA256(SHA256(m))
2. Hash function H(m) = SHA256(m)

Basics

• For a private key x, the public key is xG.
• A signature on the message m with private key x is (R, s) where R=kG, s=k+H(R,X,m)x.

arowser

#!/usr/bin/env python
"""
This script implements a handshake with a remote Lightning
Network node; see BOLT8:
https://github.com/lightningnetwork/lightning-rfc/blob/master/08-transport.md
, which is the Noise-based transport protocol
for Lightning network nodes.

Specify server, port and remote node pubkey as three command line arguments;
here's an example invocation:

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Chainstate only download - Proof of Concept

Introduction

The bitcoin blockchain is currently (9th Sept 2016) 88Gig but the Chainstate is only 1.7 Gig. That is a factor of 50 different. One concern for bitcoin at the moment is a lack of full nodes. This is partly due to the length of time to download and process the blockchain from scratch. And in addition a significant cost of hosting a full node is the cost of bandwidth for serving historical blocks - and a lot of this is to nodes that start downloading the blockchain and then abandon. A node can still operate as a full node with just a valid chainstate - there is little need for the full blockchain. From my tests only 30% of chains that start syncing get to completion.

Overview of proposal

1. Every 100'th block nodes take a snapshot of the LevelDB chainstate database.
2. They then calculate a hash of hashes of that 1.7gig database (takes about 2mins).

arowser

'use strict';

// first, run   sudo apt-get install jq nodejs npm
// second, run   npm install bluebird co   to install dependencies, and make sure bitcoin-cli can run these commands.
// third, run   node thisScript.js   and it will change all the addresses on your bitcoind into segwit addresses.
var Promise = require('bluebird');
var co = require('co');
var exec = Promise.promisify(require('child_process').exec);

var main = function() {

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What is this all about?

This tutorial will turn your Raspberry PI into a simple Bluetooth audio receiver, which plays music through connected speakers. It's like a regular car audio system, but it can be used anywhere and it's a good value.

   Audio source (i.e. smartphone) 
                |
                v
 (((  Wireless Bluetooth Channel  )))
 |

arowser

#! /bin/bash
set -e
trap 'previous_command=$this_command; this_command=$BASH_COMMAND' DEBUG
trap 'echo FAILED COMMAND: $previous_command' EXIT

#-------------------------------------------------------------------------------------------
# This script will download packages for, configure, build and install a GCC cross-compiler.
# Customize the variables (INSTALL_PATH, TARGET, etc.) to your liking before running.
# If you get an error and need to resume the script from some point in the middle,
# just delete/comment the preceding lines before running it again.

arowser

CREATE OR REPLACE FUNCTION public.json_append(data json, insert_data json)
RETURNS json
IMMUTABLE
LANGUAGE sql
AS $$
    SELECT ('{'||string_agg(to_json(key)||':'||value, ',')||'}')::json
    FROM (
        SELECT * FROM json_each(data)
        UNION ALL
        SELECT * FROM json_each(insert_data)

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./configure --disable-ccache --with-gui=qt5 --with-incompatible-bdb CC="$PWD/../devtools/mtime.sh gcc" CXX="$PWD/../devtools/mtime.sh g++" CPP="$PWD/../devtools/mtime.sh cpp"