Matthew Downey 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:

I hereby claim:

To claim this, I am signing this object:

	"""
	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

	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.

	# 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

	(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

	(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]

	(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

	(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)}

	(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]