ActiveToken¶ ↑

A simple way to create cryptographic tokens for an Active Record model.

Tokens generated using one-way cryptographic functions are a popular way to create unique opaque identifiers for objects which can be more or less safely exposed.

Typical use cases include:

• sending an invitation email with an activation link

• sending a password reset email

• creating an URL to a personalized or private feed without relying on some other authentication scheme

Usage¶ ↑

This plugin encapsulates all the process of generating and storing the token. All you need to do is to add a string column (named token by default) to the table backing your model and add one line of code to your class:

class User < ActiveRecord::Base
  has_token :made_of => [:username, :password, :created_at]
end

user = User.create(:username => 'rachel', :password => 'unicorn')
user.token # => 12b3c4f333a56...

The token column name can be changed using the :field option.

Customization¶ ↑

The default hashing method is multiple rounds SHA-1 but it can be configured (any algorithm available in the Digest module will do):

class User < ActiveRecord::Base
  has_token :made_of => [:username, :password, :created_at], :digest => 'MD5', :rounds => 5
end

You can also provide an additional salt value in the attributes list and also customize how to glue the pieces together

class User < ActiveRecord::Base
  has_token :made_of => ["My salt", :username, :password, :created_at], :join_with => "$*-/!&++"
end

You can also manually create the source data to be hashed. To do so, provide a block which should return either a string or an array of pieces to be glued together.

class Invitation < ActiveRecord::Base
  has_token do
    "#{email}#{Time.now}#{rand(1_000_000)}"
  end
end

# Or alternatively

class Invitation < ActiveRecord::Base
  has_token do
    [email, Time.now.to_s, rand(1_000_000)]
  end
end

Recalculation¶ ↑

By default, the token is only generated once when the record is initially saved, you can force an update of the token on every update:

class User < ActiveRecord::Base
  has_token :made_of => [:username, :password, :created_at], :update => true
end

Unfortunately, the value of the updated_at timestamp does not work as a token source because when the callback is fired, Rails has yet to set that attribute to the current time. You can easily work around that by passing a block to has_token:

class User < ActiveRecord::Base
  has_token :made_of => [:username, :password], :update => true do 
    Time.now
  end
end

License¶ ↑

Copyright © 2009 Xavier Defrang, released under the MIT license

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.