Simply SCrypt

For a relatively young project, do this

1. Add these to your Gemfile
```text
gem 'devise', :git => 'https://github.com/steakknife/devise.git'
gem 'scrypt'
```
2. Don't use `devise-encryptable`
3. Remove `:encryptable` from the User model
4. Set `config.encryptor = :scrypt` in config/initializers/devise.rb
5. Optionally set SCrypt settings in config/initializers/scrypt.rb
```ruby
    require 'scrypt'

    SCrypt::Engine::DEFAULTS[:key_len]     = 128
    SCrypt::Engine::DEFAULTS[:salt_size]   = 32
    SCrypt::Engine::DEFAULTS[:max_mem]     = 4*1024*1024
    SCrypt::Engine::DEFAULTS[:max_time]    = 0.4
    SCrypt::Engine::DEFAULTS[:max_memfrac] = 0.3
```
6a. Create a new migration `rails g migration DeviseScryptPasswordLength`
 
6b. Drop this into your project's migrations:
```ruby
    # db/migrate/20130331100000_devise_scrypt_password_length.rb
   class DeviseScryptPasswordLength < ActiveRecord::Migration  
      def up  
        change_column :users, :encrypted_password, :text
      end
      def down
        change_column :users, :encrypted_password, :string
      end
    end
```

Note: This does not convert passwords using Bcrypt or anything else.  It's only for projects without any existing users.