Blog Has Moved!

New address: http://www.heathanderson.net

Ruby on Rails Plugin: string_encryption

This is a very simple Ruby on Rails plugin that allows easy encryption of strings. For the sake of simplicity there no customization. The only cipher used is ‘des-ede3-cbc’ (Triple DES using Cipher Block Chaining) . See my post on encrypting/decrypting a string with Ruby for more information. First install the plugin:

 script/plugin install git://github.com/handerson/string_encryption.git

Next we need to add an encryption key as the constant ENV['STRING_ENCRYPTION_KEY']. To do this just run

 script/generate encryption_key

or you could set

ENV['STRING_ENCRYPTION_KEY'] = "somekey"

where “somekey” is your key in environment.rb.

Now encryption/decryption is easy.

Encryption:

"Test".encrypt  #=> "NDFkZTc5NDEyNTg1MzdiZPzBrxZz5aoN%0A"

Decryption:

"NDFkZTc5NDEyNTg1MzdiZPzBrxZz5aoN%0A".decrypt  #=> "Test"

Code at Github:
http://github.com/handerson/string_encryption

Initialization Vector Length in MRI Ruby versus JRuby

When using OpenSSL encryption in standard Ruby, the length of an initialization vector (IV) can apparently be as large as you want it to be as long as it is at least the minimum size. This is odd. This can also cause trouble when switching over to JRuby. JRuby appear to be much pickier about IV length.

This works in MRI but not in JRuby:

unencrypted_data = "test"

des = OpenSSL::Cipher::Cipher.new("des-ede3-cbc")
des.encrypt
des.key = '0123456789abcdef01234567890'

des.iv = "ed87acdcca419954edccb736f7dc77a74f5ac8dfe3861c3d5f77248e21592131a5423d63ff91f07956ce1aa386f8359931b5" # 100 characters
encrypted_data = des.update(unencrypted_data) + des.final

puts encrypted_data

JRuby gives you this very helpful message:
ruby_string_encryption.rb:27:in `encrypt': No message available (OpenSSL::Cipher::CipherError)
from ruby_string_encryption.rb:37

Change the IV to 8 characters and everything works fine.

Update 10/14/2009 The code that I originally posted was incorrect. I have updated it. Also I opened a ticket for this issue.

If you are looking for what size an initialization vector should be check out my post on encrypting a string with Ruby.

Ruby String Encryption

Encrypting a string is fairly easy in Ruby. All you need to do is require 'openssl'. For this example I am using the ‘des-ede3-cbc’ (Triple DES using Cipher Block Chaining) cipher. Most–if not all–of the ciphers listed on OpenSSL.org as supported ciphers should work as well.

Ruby on Rails Plugin: data_migration

data_migration allows you to separate data you need to load from your normal database migrations in a minimal way. While developing the new version of our flagship site, Knetwit, we decided we needed to separate our data migrations (initial settings and the like) from our structural migrations. We decided the easiest way to do this was to modify the existing Rails migration to allow for a new data migration. So we did.

Install Plugin

script/plugin install git://github.com/handerson/data_migration.git

Generate Migration

script/generate data_migration BlockedDomains

exists  db/data
create  db/data/20090915161242_settings.rb

db/data/20090915161242_settings.rb:

class BlockedDomains < ActiveRecord::Migration
  def self.up
  end
end

Add your data:

def self.up
  BlockedEmailDomain.create(:domain => "mailinator.com")
  BlockedEmailDomain.create(:domain => "spamherelots.com")
  BlockedEmailDomain.create(:domain => "disposeamail.com")
end

Run Migration

rake db:data:migrate

==  BlockedDomains: migrating ===========================================================
==  BlockedDomains: migrated (0.0020s) ==================================================

db:data:migrate adds the data migration version number to the ‘schema_migrations’ table so it will not be ran again.

Code at Github:
http://github.com/handerson/data_migration