hyperupcall

// I'm tired of extensions that automatically:
// - show welcome pages / walkthroughs
// - show release notes
// - send telemetry
// - recommend things
//
// This disables all of that stuff.
// If you have more config, leave a comment so I can add it!!

{

DavidBuchanan314

MD5 Collision with CRC32 Preimage

Here's the scenario: We want to craft two different messages with the same MD5 hash, and a specific CRC32 checksum, simultaneously.

In other words, we want an MD5 collision attack and a CRC32 preimage attack.

This might seem like a contrived scenario, but it's exactly the one I faced while producing my PNG hashquine (Yes OK maybe that's also a contrived scenario, cut me some slack).

On its own, a CRC32 preimage attack is trivial. You can craft a 4-byte suffix that gives any message a specific checksum, calculated using a closed-form expression (which I am too lazy to derive, not even with assistance from Z3). It's not an attack per-se, since CRC32 was never meant to be cryptograpically secure in the first place.

ttesmer

{-# LANGUAGE TypeSynonymInstances #-}
data Dual d = D Float d deriving Show
type Float' = Float

diff :: (Dual Float' -> Dual Float') -> Float -> Float'
diff f x = y'
  where D y y' = f (D x 1)

class VectorSpace v where
  zero  :: v

blackcater

Diagrams

Markdown Preview Enhanced supports rendering flow charts, sequence diagrams, mermaid, PlantUML, WaveDrom, GraphViz, Vega & Vega-lite, Ditaa diagrams. You can also render TikZ, Python Matplotlib, Plotly and all sorts of other graphs and diagrams by using Code Chunk.

Please note that some diagrams don't work well with file exports such as PDF, pandoc, etc.

Flow Charts

This feature is powered by flowchart.js.

creotiv

#Generate root password
import random, string
password = ''.join(random.choice(string.ascii_letters + string.digits) for i in range(20))

#Download ngrok
! wget -q -c -nc https://bin.equinox.io/c/4VmDzA7iaHb/ngrok-stable-linux-amd64.zip
! unzip -qq -n ngrok-stable-linux-amd64.zip
#Setup sshd
! apt-get install -qq -o=Dpkg::Use-Pty=0 openssh-server pwgen > /dev/null
#Set root password

jesperorb

Handle CORS Client-side

Cross-origin resource sharing (CORS) is a mechanism that allows restricted resources (e.g. fonts) on a web page to be requested from another domain outside the domain from which the first resource was served. This is set on the server-side and there is nothing you can do from the client-side to change that setting, that is up to the server/API. There are some ways to get around it tho.

Sources : MDN - HTTP Access Control | Wiki - CORS

CORS is set server-side by supplying each request with additional headers which allow requests to be requested outside of the own domain, for example to your localhost. This is primarily set by the header:

Access-Control-Allow-Origin

arthur-e

def convex_hull_graham(points):
    '''
    Returns points on convex hull in CCW order according to Graham's scan algorithm. 
    By Tom Switzer <thomas.switzer@gmail.com>.
    '''
    TURN_LEFT, TURN_RIGHT, TURN_NONE = (1, -1, 0)

    def cmp(a, b):
        return (a > b) - (a < b)

vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

nils-werner

from __future__ import division
import numpy

n = 1000000
# 2D data spread uniformly across a square of A=1
data = numpy.random.uniform(-0.5, 0.5, size=(n, 2))

# Count points that are within distance 0.5 from center
inside = len(
    numpy.argwhere(

willurd

Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000