Rails 4.1.0 and authlogic bcrypt issue - ruby-on-rails

Question

I'm running the latest OSX with rvm ruby 2.1.0. After bundle update to Rails 4.1.0 and authlogic 3.4.1, when I start the server I get this error:
authlogic/crypto_providers/bcrypt.rb:1:in `require': cannot load such file -- bcrypt (LoadError)
authlogic-3.4.1/lib/authlogic/crypto_providers/bcrypt.rb:1:in `<top (required)>'
authlogic-3.4.1/lib/authlogic.rb:60:in `require'
authlogic-3.4.1/lib/authlogic.rb:60:in `block in <top (required)>'
authlogic-3.4.1/lib/authlogic.rb:59:in `each'
authlogic-3.4.1/lib/authlogic.rb:59:in `<top (required)>'
bundler-1.5.2/lib/bundler/runtime.rb:76:in `require'
bundler-1.5.2/lib/bundler/runtime.rb:76:in `block (2 levels) in require'
bundler-1.5.2/lib/bundler/runtime.rb:72:in `each'
bundler-1.5.2/lib/bundler/runtime.rb:72:in `block in require'
bundler-1.5.2/lib/bundler/runtime.rb:61:in `each'
bundler-1.5.2/lib/bundler/runtime.rb:61:in `require'
bundler-1.5.2/lib/bundler.rb:131:in `require'
application.rb:7:in `<top (required)>'
railties-4.1.0/lib/rails/commands/commands_tasks.rb:79:in `require'
railties-4.1.0/lib/rails/commands/commands_tasks.rb:79:in `block in server'
railties-4.1.0/lib/rails/commands/commands_tasks.rb:76:in `tap'
railties-4.1.0/lib/rails/commands/commands_tasks.rb:76:in `server'
railties-4.1.0/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
railties-4.1.0/lib/rails/commands.rb:17:in `<top (required)>'

Answer 1

From this issue on the authlogic github account
Authlogic has changed its default encryption system from SHA512 to SCrypt.
It seems that you need this in your gemfile
gem 'authlogic', '~> 3.4.0'
gem 'scrypt'
If you don't want SCrypt you can use Sha512 by putting this
acts_as_authentic do |c|
c.crypto_provider = Authlogic::CryptoProviders::Sha512
end
in your User.rb
You also might need to specify the version of the authlogic gem
gem 'authlogic', github: 'binarylogic/authlogic', ref: 'e4b2990d6282f3f7b50249b4f639631aef68b939'
but I guess this will be fixed soon