KodrAus

Profiling performance

Using perf:

$ perf record -g binary
$ perf script | stackcollapse-perf.pl | rust-unmangle | flamegraph.pl > flame.svg

NOTE: See @GabrielMajeri's comments below about the -g option.

BrendanEich

From Fabrice Bellard, with minor name change (umulh):

// return the high 32 bit part of the 64 bit addition of (hi0, lo0) and (hi1, lo1)
Math.iaddh(lo0, hi0, lo1, hi1)

// return the high 32 bit part of the 64 bit subtraction of (hi0, lo0) and (hi1, lo1)
Math.isubh(lo0, hi0, lo1, hi1)

// return the high 32 bit part of the signed 64 bit product of the 32 bit numbers a and b

kevincennis

Installing V8 on a Mac

Prerequisites

• Install Xcode (Avaliable on the Mac App Store)
• Install Xcode Command Line Tools (Preferences > Downloads)
• Install depot_tools
  • $ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
  • $ nano ~/.zshrc
  • Add path=('/path/to/depot_tools' $path)

ryanxcharles

Stealth Addresses, Transactions and Messages

Normal bitcoin addresses cannot be published in public without losing all privacy, since all transactions to that address can be seen by anybody. Stealth addresses let us publish an address in public which can be used by payers to derive a new address that the payee has access to, but no one else knows is associated with the stealth address. The trick is that the payer must use a nonce to derive the address paid to, and this nonce must be delivered to the payee so they know how to recover the funds. This nonce can be delivered in the transaction, so that no separate channel is required to communicate the nonce.

The same technology can also be used to construct new public keys to send encrypted messages to.

We will discuss four methods:

1. The simplest form of stealth addresses, which has some drawbacks that can improved upon.

dcousens

• <> represents data or script
• {} represents data that must prefixed by OP_PUSHDATA
• [] represents multiple {}

Standard Scripts

PubKey (pay-to-pubkey / P2PK)

Address: N/A
scriptPubKey: {pubKey} OP_CHECKSIG