Understanding & Sharing Rails sessions

Understand how Rails sessions work, the crypto applied, the risks if you are using a version of Rails older than 4.1 and learn how to share the session with apps in other languages.

1. Matt Aimonetti Splice: Go, Ruby, JS, Obj-C, C#, C++, C Matt Aimonetti - splice.com - @mattetti
5. “Knowledge is power” France is Bacon
6. “Crypto is hard” Bruce Schneier
7. “Barcelona is awesome” My wife
9. The events depicted in this presentation took place in California in 2014. ! At the request of the survivors, the names have been changed. Out of respect for the dead, the rest has been told exactly as it occurred.
10. Bob Alice
11. Abe
18. Conchita
22. Dave
26. {}
27. session.current_user
30. Frank
36. ActiveSupport::MessageVerifier
37. Splice::Application.config.secret_key_base = "f7b5763636f4c1f3ff4bd444eaccaca295d87b 990cc104124017ad70550edcfd22b8e89465398 254e0b608592a9aac29025440bfd9ce42579835 ba06a86f85f9" config/initializers/secret_token.rb config/secrets.yml Before Rails 4.1 After Rails 4.1
39. key_generator = ActiveSupport::CachingKeyGenerator.new( ActiveSupport::KeyGenerator.new( secret_key_base, iterations: 1000 ) )
40. Password-Based Key Derivation Function 2 ! AKA ! PBKDF2
41. derived_secret = key_generator. generate_key("Rails salt")
43. SHA-­‐1(Secret,  Salt  +1) SHA-­‐1(Secret,  Salt) SHA-­‐1(Secret,  Salt)
44. verifier = ActiveSupport::MessageVerifier. new(derived_secret) ! msg = { user: "Matt", role: "villain"} ! signed_message = verifier.generate(msg) ! # => "BAh7BzoKd2hlcmVJIg5CYXJjZWxvbmEGOgZFVDoJd 2hhdEkiC0JhcnVjbwY7BlQ=-- ad7af07ad5b384d458b7cf8a962c04fc53ed81d1"
45. BAh7BzoKd2hlcmVJIg5CYXJjZWxvbmEGOgZFV DoJd2hhdEkiC0JhcnVjbwY7BlQ= -- ad7af07ad5b384d458b7cf8a962c04fc53ed8 1d1 Base 64 encoded version of the dumped message Signature of encoded message
46. Marshal.load(Base64.decode64(“BAh7…”)) # => {:user=>"Matt", :role=>"Villain"}
47. ActiveSupport::MessageEncryptor
48. crypt_secret = key_generator.generate_key( "signed encrypted cookie") ! encryptor = ActiveSupport::MessageEncryptor.new( secret, crypt_secret) ! message = encryptor. encrypt_and_sign({msg: "hello world"}) ! encryptor.decrypt_and_verify(message) # => {:msg => "hello world"}
59. Wendy
60. Eve
61. Splice::Application.config.secret_key_base = "f7b5763636f4c1f3ff4bd444eaccaca295d87b 990cc104124017ad70550edcfd22b8e89465398 254e0b608592a9aac29025440bfd9ce42579835 ba06a86f85f9" config/initializers/secret_token.rb config/secrets.yml
66. class ::Pwned def marshal_load(*args) end def marshal_dump end end
67. class ::Pwned def marshal_load(*args) ActiveRecord::Base.connection.tables.each do |t| ActiveRecord::Base.connection.drop_table(t) end end def marshal_dump; end def by "Eve" end end ! session[:pwned] = ::Pwned.new
69. request.cookie_jar. signed_or_encrypted. send(:serializer) ! => Marshal
70. Rails.application.config.action_dispatch. cookies_serializer = :hybrid only store simple objects!
74. http://godoc.org/github.com/mattetti/goRailsYourself/crypto
75. type Person struct { Id int `json:"id"` FirstName string `json:”first_name"` LastName string `json:”last_name"` Age int `json:"age"` } ! ! john := Person{Id: 12, FirstName: "John", LastName: "Doe", Age: 42}
76. railsSecret := "fromYourConfig" cookieSalt := []byte(“cookie_salt") signedCookieSalt := []byte("scookie")
77. kg := KeyGenerator{Secret: railsSecret} ! // derived keys secret := kg.CacheGenerate(cookieSalt, 32) signSecret := kg.CacheGenerate(signedCookieSalt, 64) ! e := MessageEncryptor{ Key: secret, SignKey: signSecret}
78. /* john := Person{Id: 12, FirstName: "John", LastName: "Doe", Age: 42} */ ! msg, err = e.EncryptAndSign(john) if err != nil { log.Fatal(err) }
79. // decrypting the person object contained in //the session var sessionContent Person err = e.DecryptAndVerify(msg, &sessionContent) if err != nil { log.Fatal(err) } // Person{Id:12, FirstName:"John", // LastName:”Doe”, Age:42}
87. Questions @mattetti ! ! splice.com