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#Simple Authentication with Bcrypt

This tutorial is for adding authentication to a vanilla Ruby on Rails app using Bcrypt and has_secure_password.

The steps below are based on Ryan Bates's approach from Railscast #250 Authentication from Scratch (revised).

You can see the final source code here: repo. I began with a stock rails app using rails new gif_vault

##Steps

OAUTH2

The Problem

I’m a web app that wants to allow other web apps access to my users’ information, but I want to ensure that the user says it’s ok.

The Solution

I can’t trust the other web apps, so I must interact with my users directly. I’ll let them know that the other app is trying to get their info, and ask whether they want to grant that permission. Oauth defines a way to initiate that permission verification from the other app’s site so that the user experience is smooth. If the user grants permission, I issue an AuthToken to the other app which it can use to make requests for that user's info.

Note on encryption

Oauth2 has nothing to do with encryption -- it relies upon SSL to keep things (like the client app’s shared_secret) secure.

A summary of the Rails Guides on Routes, plus other tips.

The Rails router recognizes URLs and dispatches them to a controller's action. It can also generate paths and URLs, avoiding the need to hardcode strings in your views.

Examples

# Redirects /orders/report to orders#report.
get 'orders/report', to: 'orders#report'

belongs_to:

Assigning an object to a belongs_to association does not automatically save the object. It does not save the associated object either.

has_one:

When you assign an object to a has_one association, that object is automatically saved (in order to update its foreign key).
In addition, any object being replaced is also automatically saved, because its foreign key will change too
If either of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
If the parent object (the one declaring the has_one association) is unsaved (that is, new_record? returns true) then the child objects are not saved. They will automatically when the parent object is saved.

Reader Macros in Common Lisp

This post also appears on lisper.in.

Reader macros are perhaps not as famous as ordinary macros. While macros are a great way to create your own DSL, reader macros provide even greater flexibility by allowing you to create entirely new syntax on top of Lisp.

Paul Graham explains them very well in [On Lisp][] (Chapter 17, Read-Macros):

The three big moments in a Lisp expression's life are read-time, compile-time, and runtime. Functions are in control at runtime. Macros give us a chance to perform transformations on programs at compile-time. ...read-macros... do their work at read-time.

Two way iframe communication

The main difference between the two pages is the method of sending messages. Recieving messages is the same in both.

Parent

Send messages to iframe using iframeEl.contentWindow.postMessage Recieve messages using window.addEventListener('message')

iframe

Exposing your clipboard over SSH

I frequently administer remote servers over SSH, and need to copy data to my clipboard. If the text I want to copy all fits on one screen, then I simply select it with my mouse and press CMD-C, which asks relies on m y terminal emulator (xterm2) to throw it to the clipboard.

This isn't practical for larger texts, like when I want to copy the whole contents of a file.

If I had been editing large-file.txt locally, I could easily copy its contents by using the pbcopy command:


	# 1) Create your private key (any password will do, we remove it below)

	$ cd ~/.ssh
	$ openssl genrsa -des3 -out server.orig.key 2048


	# 2) Remove the password

	$ openssl rsa -in server.orig.key -out server.key

	@echo off
	SET st3Path=C:\Program Files\Sublime Text 3\sublime_text.exe

	rem add it for all file types
	@reg add "HKEY_CLASSES_ROOT\*\shell\Open with Sublime Text 3" /t REG_SZ /v "" /d "Open with Sublime Text 3" /f
	@reg add "HKEY_CLASSES_ROOT\*\shell\Open with Sublime Text 3" /t REG_EXPAND_SZ /v "Icon" /d "%st3Path%,0" /f
	@reg add "HKEY_CLASSES_ROOT\*\shell\Open with Sublime Text 3\command" /t REG_SZ /v "" /d "%st3Path% \"%%1\"" /f

	rem add it for folders
	@reg add "HKEY_CLASSES_ROOT\Folder\shell\Open with Sublime Text 3" /t REG_SZ /v "" /d "Open with Sublime Text 3" /f

	require "rubygems"
	require "ffi"

	module WinProcess
	extend FFI::Library

	ffi_lib "kernel32"
	ffi_convention :stdcall

	class Error < StandardError