matthewdowney

"""
Implementation of "Pay to Witness Public Key Hash nested in BIP16 Pay to Script Hash" (P2WPKH-P2SH) address generation.
Described in BIP 141 (SegWit) https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#P2WPKH_nested_in_BIP16_P2SH

I.e.: Public key -> SegWit address
"""

import hashlib
from hashlib import sha256

matthewdowney

import hmac
from functools import wraps


def safe_equal(a, b):
    """
    Perform an equality check between strings that guards against a timing attack by checking every index in the each
    string. Note that length is compared first, so the length may be leaked through a timing attack, which does not
    compromise the security of an HMAC.

matthewdowney

# Pipe some data to stdin. Each line should contain a number.
import csv
from collections import defaultdict
from math import log10
import matplotlib
import matplotlib.pyplot as plt
import functools

import fileinput

matthewdowney

Issues with the Blockchain Info API

The blockchain.info API for XPUBs only works with Legacy Bitcoin XPUBs, whereas their web interface confusingly works with Segwit as well.

I provide a couple solutions at the end, and we end up with three useful functions:

• legacy_wallet_balance
• segwit_wallet_balance
• segwit_wallet_balance_hack

matthewdowney

(defn xf-sort
  "A sorting transducer. Mostly a syntactic improvement to allow composition of
  sorting with the standard transducers, but also provides a slight performance
  increase over transducing, sorting, and then continuing to transduce."
  ([]
   (xf-sort compare))
  ([cmp]
   (fn [rf]
     (let [temp-list (java.util.ArrayList.)]
       (fn

matthewdowney

(defn stats
  "Calculate :mean :min :max :stdev and :n given a data point, and possibly a prior `stats` result.
  I.e. to calculate statistics from scratch:
  ```
  (def statistics (reduce stats nil data-set))
  ```
  Or to maintain statistics for a constantly updating data series that you don't want to keep in memory:
  ```
  (def statistics (atom (stats 0))
  (defn add-data-point! [dp]

matthewdowney

Keybase proof

I hereby claim:

• I am matthewdowney on github.
• I am matthewdowney (https://keybase.io/matthewdowney) on keybase.
• I have a public key ASA5-6Rf3lYjOJowTXj54xl2nhKdjc1jvET1YsVd4Q0YcQo

To claim this, I am signing this object:

matthewdowney

(defn parsed-file-delay
  "A delay that returns `(parse-fn (slurp file-path))` on each dereference,
  recalculating the return value only when `(.lastModified (io/file file-path))`
  changes.
  
  Useful if you don't need any sort of push notification when the file changes."
  [file-path parse-fn]
  (let [last-contents (atom {:modified -1 :contents nil})
        ^File f (io/file file-path)]
    (reify IDeref

matthewdowney

(ns blessed-cljs.core
  "Compiles for :node-js. Attempts to connect to a TCP socket at the port
  given as a command line argument, and receives pure data specifications
  for a blessed-contrib dashboard which it updates in real time.

  Expects JSON data following the format:
    {:type (a string in gauge, table, sparkline, bar, donut, gauge, lcd, log, markdown, map)
     :meta (a map to pass to grid.set along the the contrib.object)
     :data (data to display)}

matthewdowney

(import java.util.concurrent.CountDownLatch)

(defmacro dothreads
  "Like (dotimes [i n] ...) except the body is executed concurrently, and the result is
  a map from `i` to the result (or an exception if one is thrown).

  Spins up `n-threads` threads and execute `body` in each with the thread number bound to
  the given `tid-binding`, but use a CountDownLatch to make sure they all start at as close
  to the same exact time as possible."
  [[tid-binding n-threads] & body]