Merge pull request #29716 from mikeycgto/active-support-key-rotator

Add Key Rotation to MessageEncryptor and MessageVerifier and simplify the Cookies middleware

20 files changed, 975 insertions, 253 deletions

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index a53d8efee1..1d4b27a0f9 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,3 +1,12 @@
+*   Simplify cookies middleware with key rotation support
+
+    Use the `rotate` method for both `MessageEncryptor` and
+    `MessageVerifier` to add key rotation support for encrypted and
+    signed cookies. This also helps simplify support for legacy cookie
+    security.
+
+    *Michael J Coyne*
+
 *  Use Capybara registered `:puma` server config.
 
     The Capybara registered `:puma` server ensures the puma server is run in process so
diff --git a/actionpack/lib/action_dispatch/middleware/cookies.rb b/actionpack/lib/action_dispatch/middleware/cookies.rb
index 845df500d8..b3831649a8 100644
--- a/actionpack/lib/action_dispatch/middleware/cookies.rb
+++ b/actionpack/lib/action_dispatch/middleware/cookies.rb
@@ -49,6 +49,18 @@ module ActionDispatch
       get_header Cookies::AUTHENTICATED_ENCRYPTED_COOKIE_SALT
     end
 
+    def use_authenticated_cookie_encryption
+      get_header Cookies::USE_AUTHENTICATED_COOKIE_ENCRYPTION
+    end
+
+    def encrypted_cookie_cipher
+      get_header Cookies::ENCRYPTED_COOKIE_CIPHER
+    end
+
+    def signed_cookie_digest
+      get_header Cookies::SIGNED_COOKIE_DIGEST
+    end
+
     def secret_token
       get_header Cookies::SECRET_TOKEN
     end
@@ -64,6 +76,11 @@ module ActionDispatch
     def cookies_digest
       get_header Cookies::COOKIES_DIGEST
     end
+
+    def cookies_rotations
+      get_header Cookies::COOKIES_ROTATIONS
+    end
+
     # :startdoc:
   end
 
@@ -157,10 +174,14 @@ module ActionDispatch
     ENCRYPTED_COOKIE_SALT = "action_dispatch.encrypted_cookie_salt".freeze
     ENCRYPTED_SIGNED_COOKIE_SALT = "action_dispatch.encrypted_signed_cookie_salt".freeze
     AUTHENTICATED_ENCRYPTED_COOKIE_SALT = "action_dispatch.authenticated_encrypted_cookie_salt".freeze
+    USE_AUTHENTICATED_COOKIE_ENCRYPTION = "action_dispatch.use_authenticated_cookie_encryption".freeze
+    ENCRYPTED_COOKIE_CIPHER = "action_dispatch.encrypted_cookie_cipher".freeze
+    SIGNED_COOKIE_DIGEST = "action_dispatch.signed_cookie_digest".freeze
     SECRET_TOKEN = "action_dispatch.secret_token".freeze
     SECRET_KEY_BASE = "action_dispatch.secret_key_base".freeze
     COOKIES_SERIALIZER = "action_dispatch.cookies_serializer".freeze
     COOKIES_DIGEST = "action_dispatch.cookies_digest".freeze
+    COOKIES_ROTATIONS = "action_dispatch.cookies_rotations".freeze
 
     # Cookies can typically store 4096 bytes.
     MAX_COOKIE_SIZE = 4096
@@ -201,12 +222,7 @@ module ActionDispatch
       #
       #   cookies.signed[:discount] # => 45
       def signed
-        @signed ||=
-          if upgrade_legacy_signed_cookies?
-            UpgradeLegacySignedCookieJar.new(self)
-          else
-            SignedCookieJar.new(self)
-          end
+        @signed ||= SignedKeyRotatingCookieJar.new(self)
       end
 
       # Returns a jar that'll automatically encrypt cookie values before sending them to the client and will decrypt them for read.
@@ -223,18 +239,11 @@ module ActionDispatch
       # Example:
       #
       #   cookies.encrypted[:discount] = 45
-      #   # => Set-Cookie: discount=ZS9ZZ1R4cG1pcUJ1bm80anhQang3dz09LS1mbDZDSU5scGdOT3ltQ2dTdlhSdWpRPT0%3D--ab54663c9f4e3bc340c790d6d2b71e92f5b60315; path=/
+      #   # => Set-Cookie: discount=DIQ7fw==--K3n//8vvnSbGq9dA--7Xh91HfLpwzbj1czhBiwOg==; path=/
       #
       #   cookies.encrypted[:discount] # => 45
       def encrypted
-        @encrypted ||=
-          if upgrade_legacy_signed_cookies?
-            UpgradeLegacyEncryptedCookieJar.new(self)
-          elsif upgrade_legacy_hmac_aes_cbc_cookies?
-            UpgradeLegacyHmacAesCbcCookieJar.new(self)
-          else
-            EncryptedCookieJar.new(self)
-          end
+        @encrypted ||= EncryptedKeyRotatingCookieJar.new(self)
       end
 
       # Returns the +signed+ or +encrypted+ jar, preferring +encrypted+ if +secret_key_base+ is set.
@@ -256,33 +265,17 @@ module ActionDispatch
 
         def upgrade_legacy_hmac_aes_cbc_cookies?
           request.secret_key_base.present?                       &&
-            request.authenticated_encrypted_cookie_salt.present? &&
             request.encrypted_signed_cookie_salt.present?        &&
-            request.encrypted_cookie_salt.present?
+            request.encrypted_cookie_salt.present?               &&
+            request.use_authenticated_cookie_encryption
         end
-    end
-
-    # Passing the ActiveSupport::MessageEncryptor::NullSerializer downstream
-    # to the Message{Encryptor,Verifier} allows us to handle the
-    # (de)serialization step within the cookie jar, which gives us the
-    # opportunity to detect and migrate legacy cookies.
-    module VerifyAndUpgradeLegacySignedMessage # :nodoc:
-      def initialize(*args)
-        super
-        @legacy_verifier = ActiveSupport::MessageVerifier.new(request.secret_token, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
-      end
 
-      def verify_and_upgrade_legacy_signed_message(name, signed_message)
-        deserialize(name, @legacy_verifier.verify(signed_message)).tap do |value|
-          self[name] = { value: value }
+        def encrypted_cookie_cipher
+          request.encrypted_cookie_cipher || "aes-256-gcm"
         end
-      rescue ActiveSupport::MessageVerifier::InvalidSignature
-        nil
-      end
 
-      private
-        def parse(name, signed_message)
-          super || verify_and_upgrade_legacy_signed_message(name, signed_message)
+        def signed_cookie_digest
+          request.signed_cookie_digest || "SHA1"
         end
     end
 
@@ -524,6 +517,7 @@ module ActionDispatch
 
     module SerializedCookieJars # :nodoc:
       MARSHAL_SIGNATURE = "\x04\x08".freeze
+      SERIALIZER = ActiveSupport::MessageEncryptor::NullSerializer
 
       protected
         def needs_migration?(value)
@@ -534,12 +528,16 @@ module ActionDispatch
           serializer.dump(value)
         end
 
-        def deserialize(name, value)
+        def deserialize(name)
+          rotate = false
+          value  = yield -> { rotate = true }
+
           if value
-            if needs_migration?(value)
-              Marshal.load(value).tap do |v|
-                self[name] = { value: v }
-              end
+            case
+            when needs_migration?(value)
+              self[name] = Marshal.load(value)
+            when rotate
+              self[name] = serializer.load(value)
             else
               serializer.load(value)
             end
@@ -561,24 +559,31 @@ module ActionDispatch
         def digest
           request.cookies_digest || "SHA1"
         end
-
-        def key_generator
-          request.key_generator
-        end
     end
 
-    class SignedCookieJar < AbstractCookieJar # :nodoc:
+    class SignedKeyRotatingCookieJar < AbstractCookieJar # :nodoc:
       include SerializedCookieJars
 
       def initialize(parent_jar)
         super
-        secret = key_generator.generate_key(request.signed_cookie_salt)
-        @verifier = ActiveSupport::MessageVerifier.new(secret, digest: digest, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
+
+        secret = request.key_generator.generate_key(request.signed_cookie_salt)
+        @verifier = ActiveSupport::MessageVerifier.new(secret, digest: signed_cookie_digest, serializer: SERIALIZER)
+
+        request.cookies_rotations.signed.each do |rotation_options|
+          @verifier.rotate serializer: SERIALIZER, **rotation_options
+        end
+
+        if upgrade_legacy_signed_cookies?
+          @verifier.rotate raw_key: request.secret_token, serializer: SERIALIZER
+        end
       end
 
       private
         def parse(name, signed_message)
-          deserialize name, @verifier.verified(signed_message)
+          deserialize(name) do |rotate|
+            @verifier.verified(signed_message, on_rotation: rotate)
+          end
         end
 
         def commit(options)
@@ -588,37 +593,38 @@ module ActionDispatch
         end
     end
 
-    # UpgradeLegacySignedCookieJar is used instead of SignedCookieJar if
-    # secrets.secret_token and secret_key_base are both set. It reads
-    # legacy cookies signed with the old dummy key generator and signs and
-    # re-saves them using the new key generator to provide a smooth upgrade path.
-    class UpgradeLegacySignedCookieJar < SignedCookieJar #:nodoc:
-      include VerifyAndUpgradeLegacySignedMessage
-    end
-
-    class EncryptedCookieJar < AbstractCookieJar # :nodoc:
+    class EncryptedKeyRotatingCookieJar < AbstractCookieJar # :nodoc:
       include SerializedCookieJars
 
       def initialize(parent_jar)
         super
 
-        if ActiveSupport::LegacyKeyGenerator === key_generator
-          raise "You didn't set secret_key_base, which is required for this cookie jar. " \
-            "Read the upgrade documentation to learn more about this new config option."
+        key_len = ActiveSupport::MessageEncryptor.key_len(encrypted_cookie_cipher)
+        secret = request.key_generator.generate_key(request.authenticated_encrypted_cookie_salt, key_len)
+        @encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: encrypted_cookie_cipher, serializer: SERIALIZER)
+
+        request.cookies_rotations.encrypted.each do |rotation_options|
+          @encryptor.rotate serializer: SERIALIZER, **rotation_options
         end
 
-        cipher = "aes-256-gcm"
-        key_len = ActiveSupport::MessageEncryptor.key_len(cipher)
-        secret = key_generator.generate_key(request.authenticated_encrypted_cookie_salt || "")[0, key_len]
+        if upgrade_legacy_hmac_aes_cbc_cookies?
+          @encryptor.rotate \
+            key_generator: request.key_generator, salt: request.encrypted_cookie_salt, signed_salt: request.encrypted_signed_cookie_salt,
+            cipher: "aes-256-cbc", digest: digest, serializer: SERIALIZER
+        end
 
-        @encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
+        if upgrade_legacy_signed_cookies?
+          @legacy_verifier = ActiveSupport::MessageVerifier.new(request.secret_token, digest: digest, serializer: SERIALIZER)
+        end
       end
 
       private
         def parse(name, encrypted_message)
-          deserialize name, @encryptor.decrypt_and_verify(encrypted_message)
-        rescue ActiveSupport::MessageVerifier::InvalidSignature, ActiveSupport::MessageEncryptor::InvalidMessage
-          nil
+          deserialize(name) do |rotate|
+            @encryptor.decrypt_and_verify(encrypted_message, on_rotation: rotate)
+          end
+        rescue ActiveSupport::MessageEncryptor::InvalidMessage, ActiveSupport::MessageVerifier::InvalidSignature
+          parse_legacy_signed_message(name, encrypted_message)
         end
 
         def commit(options)
@@ -626,39 +632,15 @@ module ActionDispatch
 
           raise CookieOverflow if options[:value].bytesize > MAX_COOKIE_SIZE
         end
-    end
 
-    # UpgradeLegacyEncryptedCookieJar is used by ActionDispatch::Session::CookieStore
-    # instead of EncryptedCookieJar if secrets.secret_token and secret_key_base
-    # are both set. It reads legacy cookies signed with the old dummy key generator and
-    # encrypts and re-saves them using the new key generator to provide a smooth upgrade path.
-    class UpgradeLegacyEncryptedCookieJar < EncryptedCookieJar #:nodoc:
-      include VerifyAndUpgradeLegacySignedMessage
-    end
+        def parse_legacy_signed_message(name, legacy_signed_message)
+          if defined?(@legacy_verifier)
+            deserialize(name) do |rotate|
+              rotate.call
 
-    # UpgradeLegacyHmacAesCbcCookieJar is used by ActionDispatch::Session::CookieStore
-    # to upgrade cookies encrypted with AES-256-CBC with HMAC to AES-256-GCM
-    class UpgradeLegacyHmacAesCbcCookieJar < EncryptedCookieJar
-      def initialize(parent_jar)
-        super
-
-        secret = key_generator.generate_key(request.encrypted_cookie_salt || "")[0, ActiveSupport::MessageEncryptor.key_len]
-        sign_secret = key_generator.generate_key(request.encrypted_signed_cookie_salt || "")
-
-        @legacy_encryptor = ActiveSupport::MessageEncryptor.new(secret, sign_secret, cipher: "aes-256-cbc", digest: digest, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
-      end
-
-      def decrypt_and_verify_legacy_encrypted_message(name, signed_message)
-        deserialize(name, @legacy_encryptor.decrypt_and_verify(signed_message)).tap do |value|
-          self[name] = { value: value }
-        end
-      rescue ActiveSupport::MessageVerifier::InvalidSignature, ActiveSupport::MessageEncryptor::InvalidMessage
-        nil
-      end
-
-      private
-        def parse(name, signed_message)
-          super || decrypt_and_verify_legacy_encrypted_message(name, signed_message)
+              @legacy_verifier.verified(legacy_signed_message)
+            end
+          end
         end
     end
 
diff --git a/actionpack/lib/action_dispatch/railtie.rb b/actionpack/lib/action_dispatch/railtie.rb
index 4743a7ce61..855f2ffa47 100644
--- a/actionpack/lib/action_dispatch/railtie.rb
+++ b/actionpack/lib/action_dispatch/railtie.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "action_dispatch"
+require "active_support/messages/rotation_configuration"
 
 module ActionDispatch
   class Railtie < Rails::Railtie # :nodoc:
@@ -18,6 +19,7 @@ module ActionDispatch
     config.action_dispatch.signed_cookie_salt = "signed cookie"
     config.action_dispatch.encrypted_cookie_salt = "encrypted cookie"
     config.action_dispatch.encrypted_signed_cookie_salt = "signed encrypted cookie"
+    config.action_dispatch.authenticated_encrypted_cookie_salt = "authenticated encrypted cookie"
     config.action_dispatch.use_authenticated_cookie_encryption = false
     config.action_dispatch.perform_deep_munge = true
 
@@ -27,6 +29,8 @@ module ActionDispatch
       "X-Content-Type-Options" => "nosniff"
     }
 
+    config.action_dispatch.cookies_rotations = ActiveSupport::Messages::RotationConfiguration.new
+
     config.eager_load_namespaces << ActionDispatch
 
     initializer "action_dispatch.configure" do |app|
@@ -39,8 +43,6 @@ module ActionDispatch
       ActionDispatch::ExceptionWrapper.rescue_responses.merge!(config.action_dispatch.rescue_responses)
       ActionDispatch::ExceptionWrapper.rescue_templates.merge!(config.action_dispatch.rescue_templates)
 
-      config.action_dispatch.authenticated_encrypted_cookie_salt = "authenticated encrypted cookie" if config.action_dispatch.use_authenticated_cookie_encryption
-
       config.action_dispatch.always_write_cookie = Rails.env.development? if config.action_dispatch.always_write_cookie.nil?
       ActionDispatch::Cookies::CookieJar.always_write_cookie = config.action_dispatch.always_write_cookie
 
diff --git a/actionpack/test/controller/flash_test.rb b/actionpack/test/controller/flash_test.rb
index d92ae0b817..34bc2c0caa 100644
--- a/actionpack/test/controller/flash_test.rb
+++ b/actionpack/test/controller/flash_test.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require "abstract_unit"
-require "active_support/key_generator"
+require "active_support/messages/rotation_configuration"
 
 class FlashTest < ActionController::TestCase
   class TestController < ActionController::Base
@@ -243,6 +243,7 @@ end
 class FlashIntegrationTest < ActionDispatch::IntegrationTest
   SessionKey = "_myapp_session"
   Generator  = ActiveSupport::LegacyKeyGenerator.new("b3c631c314c0bbca50c1b2843150fe33")
+  Rotations  = ActiveSupport::Messages::RotationConfiguration.new
 
   class TestController < ActionController::Base
     add_flash_types :bar
@@ -348,6 +349,7 @@ class FlashIntegrationTest < ActionDispatch::IntegrationTest
       args[0] ||= {}
       args[0][:env] ||= {}
       args[0][:env]["action_dispatch.key_generator"] ||= Generator
+      args[0][:env]["action_dispatch.cookies_rotations"] = Rotations
       super(path, *args)
     end
 
diff --git a/actionpack/test/controller/request_forgery_protection_test.rb b/actionpack/test/controller/request_forgery_protection_test.rb
index 12ae95d602..eb3d2f34a8 100644
--- a/actionpack/test/controller/request_forgery_protection_test.rb
+++ b/actionpack/test/controller/request_forgery_protection_test.rb
@@ -2,6 +2,7 @@
 
 require "abstract_unit"
 require "active_support/log_subscriber/test_helper"
+require "active_support/messages/rotation_configuration"
 
 # common controller actions
 module RequestForgeryProtectionActions
@@ -630,13 +631,14 @@ end
 
 class RequestForgeryProtectionControllerUsingNullSessionTest < ActionController::TestCase
   class NullSessionDummyKeyGenerator
-    def generate_key(secret)
+    def generate_key(secret, length = nil)
       "03312270731a2ed0d11ed091c2338a06"
     end
   end
 
   def setup
     @request.env[ActionDispatch::Cookies::GENERATOR_KEY] = NullSessionDummyKeyGenerator.new
+    @request.env[ActionDispatch::Cookies::COOKIES_ROTATIONS] = ActiveSupport::Messages::RotationConfiguration.new
   end
 
   test "should allow to set signed cookies" do
diff --git a/actionpack/test/dispatch/cookies_test.rb b/actionpack/test/dispatch/cookies_test.rb
index cb225c0f62..706d0be9c2 100644
--- a/actionpack/test/dispatch/cookies_test.rb
+++ b/actionpack/test/dispatch/cookies_test.rb
@@ -3,7 +3,7 @@
 require "abstract_unit"
 require "openssl"
 require "active_support/key_generator"
-require "active_support/message_verifier"
+require "active_support/messages/rotation_configuration"
 
 class CookieJarTest < ActiveSupport::TestCase
   attr_reader :request
@@ -287,15 +287,25 @@ class CookiesTest < ActionController::TestCase
 
   tests TestController
 
-  SALT = "b3c631c314c0bbca50c1b2843150fe33"
+  SECRET_KEY_BASE = "b3c631c314c0bbca50c1b2843150fe33"
+  SIGNED_COOKIE_SALT = "signed cookie"
+  ENCRYPTED_COOKIE_SALT = "encrypted cookie"
+  ENCRYPTED_SIGNED_COOKIE_SALT = "sigend encrypted cookie"
+  AUTHENTICATED_ENCRYPTED_COOKIE_SALT = "authenticated encrypted cookie"
 
   def setup
     super
 
-    @request.env["action_dispatch.key_generator"] = ActiveSupport::KeyGenerator.new(SALT, iterations: 2)
+    @request.env["action_dispatch.key_generator"] = ActiveSupport::KeyGenerator.new(SECRET_KEY_BASE, iterations: 2)
+    @request.env["action_dispatch.cookies_rotations"] = ActiveSupport::Messages::RotationConfiguration.new
 
-    @request.env["action_dispatch.signed_cookie_salt"] =
-      @request.env["action_dispatch.authenticated_encrypted_cookie_salt"] = SALT
+    @request.env["action_dispatch.secret_key_base"] = SECRET_KEY_BASE
+    @request.env["action_dispatch.use_authenticated_cookie_encryption"] = true
+
+    @request.env["action_dispatch.signed_cookie_salt"] = SIGNED_COOKIE_SALT
+    @request.env["action_dispatch.encrypted_cookie_salt"] = ENCRYPTED_COOKIE_SALT
+    @request.env["action_dispatch.encrypted_signed_cookie_salt"] = ENCRYPTED_SIGNED_COOKIE_SALT
+    @request.env["action_dispatch.authenticated_encrypted_cookie_salt"] = AUTHENTICATED_ENCRYPTED_COOKIE_SALT
 
     @request.host = "www.nextangle.com"
   end
@@ -430,28 +440,96 @@ class CookiesTest < ActionController::TestCase
     assert_equal 45, cookies.signed[:user_id]
 
     key_generator = @request.env["action_dispatch.key_generator"]
-    signed_cookie_salt = @request.env["action_dispatch.signed_cookie_salt"]
-    secret = key_generator.generate_key(signed_cookie_salt)
+    secret = key_generator.generate_key(@request.env["action_dispatch.signed_cookie_salt"])
 
     verifier = ActiveSupport::MessageVerifier.new(secret, serializer: Marshal, digest: "SHA1")
     assert_equal verifier.generate(45), cookies[:user_id]
   end
 
   def test_signed_cookie_using_custom_digest
-    @request.env["action_dispatch.cookies_digest"] = "SHA256"
+    @request.env["action_dispatch.signed_cookie_digest"] = "SHA256"
+
     get :set_signed_cookie
     cookies = @controller.send :cookies
     assert_not_equal 45, cookies[:user_id]
     assert_equal 45, cookies.signed[:user_id]
 
     key_generator = @request.env["action_dispatch.key_generator"]
-    signed_cookie_salt = @request.env["action_dispatch.signed_cookie_salt"]
-    secret = key_generator.generate_key(signed_cookie_salt)
+    secret = key_generator.generate_key(@request.env["action_dispatch.signed_cookie_salt"])
 
     verifier = ActiveSupport::MessageVerifier.new(secret, serializer: Marshal, digest: "SHA256")
     assert_equal verifier.generate(45), cookies[:user_id]
   end
 
+  def test_signed_cookie_rotations_with_secret_key_base_and_digest
+    rotated_secret_key_base = "b3c631c314c0bbca50c1b2843150fe33"
+    rotated_salt = "signed cookie"
+
+    @request.env["action_dispatch.signed_cookie_digest"] = "SHA256"
+    @request.env["action_dispatch.cookies_rotations"].rotate :signed,
+      secret: rotated_secret_key_base, salt: rotated_salt, digest: "SHA1"
+
+    old_secret = ActiveSupport::KeyGenerator.new(rotated_secret_key_base, iterations: 1000).generate_key(rotated_salt)
+    old_message = ActiveSupport::MessageVerifier.new(old_secret, digest: "SHA1", serializer: Marshal).generate(45)
+
+    @request.headers["Cookie"] = "user_id=#{old_message}"
+
+    get :get_signed_cookie
+    assert_equal 45, @controller.send(:cookies).signed[:user_id]
+
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key(@request.env["action_dispatch.signed_cookie_salt"])
+    verifier = ActiveSupport::MessageVerifier.new(secret, digest: "SHA256", serializer: Marshal)
+    assert_equal 45, verifier.verify(@response.cookies["user_id"])
+  end
+
+  def test_signed_cookie_rotations_with_raw_key_and_digest
+    rotated_raw_key = "b3c631c314c0bbca50c1b2843150fe33"
+
+    @request.env["action_dispatch.signed_cookie_digest"] = "SHA256"
+    @request.env["action_dispatch.cookies_rotations"].rotate :signed,
+      raw_key: rotated_raw_key, digest: "SHA1"
+
+    old_message = ActiveSupport::MessageVerifier.new(rotated_raw_key, digest: "SHA1", serializer: Marshal).generate(45)
+
+    @request.headers["Cookie"] = "user_id=#{old_message}"
+
+    get :get_signed_cookie
+    assert_equal 45, @controller.send(:cookies).signed[:user_id]
+
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key(@request.env["action_dispatch.signed_cookie_salt"])
+    verifier = ActiveSupport::MessageVerifier.new(secret, digest: "SHA256", serializer: Marshal)
+    assert_equal 45, verifier.verify(@response.cookies["user_id"])
+  end
+
+  def test_signed_cookie_with_legacy_secret_scheme
+    @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
+
+    old_message = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33", digest: "SHA1", serializer: Marshal).generate(45)
+
+    @request.headers["Cookie"] = "user_id=#{old_message}"
+    get :get_signed_cookie
+    assert_equal 45, @controller.send(:cookies).signed[:user_id]
+
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key("signed cookie")
+    verifier = ActiveSupport::MessageVerifier.new(secret, digest: "SHA1", serializer: Marshal)
+    assert_equal 45, verifier.verify(@response.cookies["user_id"])
+  end
+
+  def test_tampered_with_signed_cookie
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key(@request.env["action_dispatch.signed_cookie_salt"])
+
+    verifier = ActiveSupport::MessageVerifier.new(secret, serializer: Marshal, digest: "SHA1")
+    message = verifier.generate(45)
+
+    @request.headers["Cookie"] = "user_id=#{Marshal.dump 45}--#{message.split("--").last}"
+    get :get_signed_cookie
+    assert_nil @controller.send(:cookies).signed[:user_id]
+  end
+
   def test_signed_cookie_using_default_serializer
     get :set_signed_cookie
     cookies = @controller.send :cookies
@@ -494,8 +572,7 @@ class CookiesTest < ActionController::TestCase
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
 
     key_generator = @request.env["action_dispatch.key_generator"]
-    signed_cookie_salt = @request.env["action_dispatch.signed_cookie_salt"]
-    secret = key_generator.generate_key(signed_cookie_salt)
+    secret = key_generator.generate_key(@request.env["action_dispatch.signed_cookie_salt"])
 
     marshal_value = ActiveSupport::MessageVerifier.new(secret, serializer: Marshal).generate(45)
     @request.headers["Cookie"] = "user_id=#{marshal_value}"
@@ -514,8 +591,8 @@ class CookiesTest < ActionController::TestCase
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
 
     key_generator = @request.env["action_dispatch.key_generator"]
-    signed_cookie_salt = @request.env["action_dispatch.signed_cookie_salt"]
-    secret = key_generator.generate_key(signed_cookie_salt)
+    secret = key_generator.generate_key(@request.env["action_dispatch.signed_cookie_salt"])
+
     json_value = ActiveSupport::MessageVerifier.new(secret, serializer: JSON).generate(45)
     @request.headers["Cookie"] = "user_id=#{json_value}"
 
@@ -578,11 +655,10 @@ class CookiesTest < ActionController::TestCase
   def test_encrypted_cookie_using_hybrid_serializer_can_migrate_marshal_dumped_value_to_json
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
 
-    cipher = "aes-256-gcm"
-    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
-    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: Marshal)
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key(@request.env["action_dispatch.authenticated_encrypted_cookie_salt"], 32)
 
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: Marshal)
     marshal_value = encryptor.encrypt_and_sign("bar")
     @request.headers["Cookie"] = "foo=#{::Rack::Utils.escape marshal_value}"
 
@@ -592,7 +668,7 @@ class CookiesTest < ActionController::TestCase
     assert_not_equal "bar", cookies[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
 
-    json_encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
+    json_encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: JSON)
     assert_not_nil @response.cookies["foo"]
     assert_equal "bar", json_encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
@@ -600,11 +676,10 @@ class CookiesTest < ActionController::TestCase
   def test_encrypted_cookie_using_hybrid_serializer_can_read_from_json_dumped_value
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
 
-    cipher = "aes-256-gcm"
-    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
-    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key(@request.env["action_dispatch.authenticated_encrypted_cookie_salt"], 32)
 
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: JSON)
     json_value = encryptor.encrypt_and_sign("bar")
     @request.headers["Cookie"] = "foo=#{::Rack::Utils.escape json_value}"
 
@@ -691,65 +766,8 @@ class CookiesTest < ActionController::TestCase
     }
   end
 
-  def test_signed_uses_signed_cookie_jar_if_only_secret_token_is_set
-    @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = nil
-    get :set_signed_cookie
-    assert_kind_of ActionDispatch::Cookies::SignedCookieJar, cookies.signed
-  end
-
-  def test_signed_uses_signed_cookie_jar_if_only_secret_key_base_is_set
-    @request.env["action_dispatch.secret_token"] = nil
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    get :set_signed_cookie
-    assert_kind_of ActionDispatch::Cookies::SignedCookieJar, cookies.signed
-  end
-
-  def test_signed_uses_upgrade_legacy_signed_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
-    @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    get :set_signed_cookie
-    assert_kind_of ActionDispatch::Cookies::UpgradeLegacySignedCookieJar, cookies.signed
-  end
-
-  def test_signed_or_encrypted_uses_signed_cookie_jar_if_only_secret_token_is_set
-    @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = nil
-    get :get_encrypted_cookie
-    assert_kind_of ActionDispatch::Cookies::SignedCookieJar, cookies.signed_or_encrypted
-  end
-
-  def test_signed_or_encrypted_uses_encrypted_cookie_jar_if_only_secret_key_base_is_set
-    @request.env["action_dispatch.secret_token"] = nil
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    get :get_encrypted_cookie
-    assert_kind_of ActionDispatch::Cookies::EncryptedCookieJar, cookies.signed_or_encrypted
-  end
-
-  def test_signed_or_encrypted_uses_upgrade_legacy_encrypted_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
-    @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    get :get_encrypted_cookie
-    assert_kind_of ActionDispatch::Cookies::UpgradeLegacyEncryptedCookieJar, cookies.signed_or_encrypted
-  end
-
-  def test_encrypted_uses_encrypted_cookie_jar_if_only_secret_key_base_is_set
-    @request.env["action_dispatch.secret_token"] = nil
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    get :get_encrypted_cookie
-    assert_kind_of ActionDispatch::Cookies::EncryptedCookieJar, cookies.encrypted
-  end
-
-  def test_encrypted_uses_upgrade_legacy_encrypted_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
-    @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    get :get_encrypted_cookie
-    assert_kind_of ActionDispatch::Cookies::UpgradeLegacyEncryptedCookieJar, cookies.encrypted
-  end
-
   def test_legacy_signed_cookie_is_read_and_transparently_upgraded_by_signed_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33").generate(45)
 
@@ -766,9 +784,6 @@ class CookiesTest < ActionController::TestCase
 
   def test_legacy_signed_cookie_is_read_and_transparently_encrypted_by_encrypted_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    @request.env["action_dispatch.encrypted_cookie_salt"] = "4433796b79d99a7735553e316522acee"
-    @request.env["action_dispatch.encrypted_signed_cookie_salt"] = "00646eb40062e1b1deff205a27cd30f9"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33").generate("bar")
 
@@ -777,17 +792,14 @@ class CookiesTest < ActionController::TestCase
 
     assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
 
-    cipher = "aes-256-gcm"
-    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
-    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: Marshal)
+    secret = @request.env["action_dispatch.key_generator"].generate_key(@request.env["action_dispatch.authenticated_encrypted_cookie_salt"], 32)
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: Marshal)
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
   def test_legacy_json_signed_cookie_is_read_and_transparently_upgraded_by_signed_json_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.cookies_serializer"] = :json
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33", serializer: JSON).generate(45)
 
@@ -805,7 +817,6 @@ class CookiesTest < ActionController::TestCase
   def test_legacy_json_signed_cookie_is_read_and_transparently_encrypted_by_encrypted_json_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.cookies_serializer"] = :json
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33", serializer: JSON).generate("bar")
 
@@ -824,7 +835,6 @@ class CookiesTest < ActionController::TestCase
   def test_legacy_json_signed_cookie_is_read_and_transparently_upgraded_by_signed_json_hybrid_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33", serializer: JSON).generate(45)
 
@@ -842,7 +852,6 @@ class CookiesTest < ActionController::TestCase
   def test_legacy_json_signed_cookie_is_read_and_transparently_encrypted_by_encrypted_hybrid_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33", serializer: JSON).generate("bar")
 
@@ -851,17 +860,15 @@ class CookiesTest < ActionController::TestCase
 
     assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
 
-    cipher = "aes-256-gcm"
     salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
-    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len("aes-256-gcm")]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: JSON)
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
   def test_legacy_marshal_signed_cookie_is_read_and_transparently_upgraded_by_signed_json_hybrid_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33").generate(45)
 
@@ -878,6 +885,8 @@ class CookiesTest < ActionController::TestCase
 
   def test_legacy_marshal_signed_cookie_is_read_and_transparently_encrypted_by_encrypted_hybrid_cookie_jar_if_both_secret_token_and_secret_key_base_are_set
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
+
+    @request.env["action_dispatch.use_authenticated_cookie_encryption"] = true
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
     @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
@@ -888,16 +897,14 @@ class CookiesTest < ActionController::TestCase
 
     assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
 
-    cipher = "aes-256-gcm"
     salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
-    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len("aes-256-gcm")]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: JSON)
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
   def test_legacy_signed_cookie_is_treated_as_nil_by_signed_cookie_jar_if_tampered
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     @request.headers["Cookie"] = "user_id=45"
     get :get_signed_cookie
@@ -908,7 +915,6 @@ class CookiesTest < ActionController::TestCase
 
   def test_legacy_signed_cookie_is_treated_as_nil_by_encrypted_cookie_jar_if_tampered
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
 
     @request.headers["Cookie"] = "foo=baz"
     get :get_encrypted_cookie
@@ -918,17 +924,12 @@ class CookiesTest < ActionController::TestCase
   end
 
   def test_legacy_hmac_aes_cbc_encrypted_marshal_cookie_is_upgraded_to_authenticated_encrypted_cookie
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-
-    @request.env["action_dispatch.encrypted_cookie_salt"] =
-      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
-
     key_generator = @request.env["action_dispatch.key_generator"]
     encrypted_cookie_salt = @request.env["action_dispatch.encrypted_cookie_salt"]
     encrypted_signed_cookie_salt = @request.env["action_dispatch.encrypted_signed_cookie_salt"]
-    secret = key_generator.generate_key(encrypted_cookie_salt)
+    secret = key_generator.generate_key(encrypted_cookie_salt, ActiveSupport::MessageEncryptor.key_len("aes-256-cbc"))
     sign_secret = key_generator.generate_key(encrypted_signed_cookie_salt)
-    marshal_value = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: Marshal).encrypt_and_sign("bar")
+    marshal_value = ActiveSupport::MessageEncryptor.new(secret, sign_secret, cipher: "aes-256-cbc", serializer: Marshal).encrypt_and_sign("bar")
 
     @request.headers["Cookie"] = "foo=#{marshal_value}"
 
@@ -938,27 +939,22 @@ class CookiesTest < ActionController::TestCase
     assert_not_equal "bar", cookies[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
 
-    aead_cipher = "aes-256-gcm"
     aead_salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    aead_secret = key_generator.generate_key(aead_salt)[0, ActiveSupport::MessageEncryptor.key_len(aead_cipher)]
-    aead_encryptor = ActiveSupport::MessageEncryptor.new(aead_secret, cipher: aead_cipher, serializer: Marshal)
+    aead_secret = key_generator.generate_key(aead_salt, ActiveSupport::MessageEncryptor.key_len("aes-256-gcm"))
+    aead_encryptor = ActiveSupport::MessageEncryptor.new(aead_secret, cipher: "aes-256-gcm", serializer: Marshal)
 
     assert_equal "bar", aead_encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
   def test_legacy_hmac_aes_cbc_encrypted_json_cookie_is_upgraded_to_authenticated_encrypted_cookie
     @request.env["action_dispatch.cookies_serializer"] = :json
-    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-
-    @request.env["action_dispatch.encrypted_cookie_salt"] =
-      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
 
     key_generator = @request.env["action_dispatch.key_generator"]
     encrypted_cookie_salt = @request.env["action_dispatch.encrypted_cookie_salt"]
     encrypted_signed_cookie_salt = @request.env["action_dispatch.encrypted_signed_cookie_salt"]
-    secret = key_generator.generate_key(encrypted_cookie_salt)
+    secret = key_generator.generate_key(encrypted_cookie_salt, ActiveSupport::MessageEncryptor.key_len("aes-256-cbc"))
     sign_secret = key_generator.generate_key(encrypted_signed_cookie_salt)
-    marshal_value = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: JSON).encrypt_and_sign("bar")
+    marshal_value = ActiveSupport::MessageEncryptor.new(secret, sign_secret, cipher: "aes-256-cbc", serializer: JSON).encrypt_and_sign("bar")
 
     @request.headers["Cookie"] = "foo=#{marshal_value}"
 
@@ -968,19 +964,17 @@ class CookiesTest < ActionController::TestCase
     assert_not_equal "bar", cookies[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
 
-    aead_cipher = "aes-256-gcm"
     aead_salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    aead_secret = key_generator.generate_key(aead_salt)[0, ActiveSupport::MessageEncryptor.key_len(aead_cipher)]
-    aead_encryptor = ActiveSupport::MessageEncryptor.new(aead_secret, cipher: aead_cipher, serializer: JSON)
+    aead_secret = key_generator.generate_key(aead_salt)[0, ActiveSupport::MessageEncryptor.key_len("aes-256-gcm")]
+    aead_encryptor = ActiveSupport::MessageEncryptor.new(aead_secret, cipher: "aes-256-gcm", serializer: JSON)
 
     assert_equal "bar", aead_encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
   def test_legacy_hmac_aes_cbc_encrypted_cookie_using_64_byte_key_is_upgraded_to_authenticated_encrypted_cookie
     @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-
-    @request.env["action_dispatch.encrypted_cookie_salt"] =
-      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
+    @request.env["action_dispatch.encrypted_cookie_salt"] = "b3c631c314c0bbca50c1b2843150fe33"
+    @request.env["action_dispatch.encrypted_signed_cookie_salt"] = "b3c631c314c0bbca50c1b2843150fe33"
 
     # Cookie generated with 64 bytes secret
     message = ["566d4e75536d686e633246564e6b493062557079626c566d51574d30515430394c53315665564a694e4563786555744f57537454576b396a5a31566a626e52525054303d2d2d34663234333330623130623261306163363562316266323335396164666364613564643134623131"].pack("H*")
@@ -991,15 +985,60 @@ class CookiesTest < ActionController::TestCase
     cookies = @controller.send :cookies
     assert_not_equal "bar", cookies[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
-    cipher = "aes-256-gcm"
 
     salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
-    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
-    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: Marshal)
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt, ActiveSupport::MessageEncryptor.key_len("aes-256-gcm"))
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: Marshal)
 
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
+  def test_encrypted_cookie_rotations_with_secret_and_salt
+    rotated_secret_key_base = "b3c631c314c0bbca50c1b2843150fe33"
+    rotated_salt = "authenticated encrypted cookie"
+
+    @request.env["action_dispatch.encrypted_cookie_cipher"] = "aes-256-gcm"
+    @request.env["action_dispatch.cookies_rotations"].rotate :encrypted,
+      secret: rotated_secret_key_base, salt: rotated_salt, cipher: "aes-256-gcm"
+
+    key_len = ActiveSupport::MessageEncryptor.key_len("aes-256-gcm")
+
+    old_secret = ActiveSupport::KeyGenerator.new(rotated_secret_key_base, iterations: 1000).generate_key(rotated_salt, key_len)
+    old_message = ActiveSupport::MessageEncryptor.new(old_secret, cipher: "aes-256-gcm", serializer: Marshal).encrypt_and_sign("bar")
+
+    @request.headers["Cookie"] = "foo=#{::Rack::Utils.escape old_message}"
+
+    get :get_encrypted_cookie
+    assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
+
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key(@request.env["action_dispatch.authenticated_encrypted_cookie_salt"], key_len)
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: Marshal)
+    assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
+  end
+
+  def test_encrypted_cookie_rotations_with_raw_key
+    raw_key = "b3c631c314c0bbca50c1b2843150fe33"
+
+    @request.env["action_dispatch.encrypted_cookie_cipher"] = "aes-256-gcm"
+    @request.env["action_dispatch.cookies_rotations"].rotate :encrypted,
+      raw_key: raw_key, cipher: "aes-256-gcm"
+
+    key_len = ActiveSupport::MessageEncryptor.key_len("aes-256-gcm")
+
+    old_message = ActiveSupport::MessageEncryptor.new(raw_key, cipher: "aes-256-gcm", serializer: Marshal).encrypt_and_sign(45)
+
+    @request.headers["Cookie"] = "foo=#{::Rack::Utils.escape old_message}"
+
+    get :get_encrypted_cookie
+    assert_equal 45, @controller.send(:cookies).encrypted[:foo]
+
+    key_generator = @request.env["action_dispatch.key_generator"]
+    secret = key_generator.generate_key(@request.env["action_dispatch.authenticated_encrypted_cookie_salt"], key_len)
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: "aes-256-gcm", serializer: Marshal)
+    assert_equal 45, encryptor.decrypt_and_verify(@response.cookies["foo"])
+  end
+
   def test_cookie_with_all_domain_option
     get :set_cookie_with_domain
     assert_response :success
diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 446b65a9b9..44f902c163 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -3,6 +3,7 @@
 require "erb"
 require "abstract_unit"
 require "controller/fake_controllers"
+require "active_support/messages/rotation_configuration"
 
 class TestRoutingMapper < ActionDispatch::IntegrationTest
   SprocketsApp = lambda { |env|
@@ -4947,6 +4948,7 @@ end
 class FlashRedirectTest < ActionDispatch::IntegrationTest
   SessionKey = "_myapp_session"
   Generator  = ActiveSupport::LegacyKeyGenerator.new("b3c631c314c0bbca50c1b2843150fe33")
+  Rotations  = ActiveSupport::Messages::RotationConfiguration.new
 
   class KeyGeneratorMiddleware
     def initialize(app)
@@ -4955,6 +4957,8 @@ class FlashRedirectTest < ActionDispatch::IntegrationTest
 
     def call(env)
       env["action_dispatch.key_generator"] ||= Generator
+      env["action_dispatch.cookies_rotations"] ||= Rotations
+
       @app.call(env)
     end
   end
diff --git a/actionpack/test/dispatch/session/cookie_store_test.rb b/actionpack/test/dispatch/session/cookie_store_test.rb
index 6517cf4c99..cf51c47068 100644
--- a/actionpack/test/dispatch/session/cookie_store_test.rb
+++ b/actionpack/test/dispatch/session/cookie_store_test.rb
@@ -3,11 +3,13 @@
 require "abstract_unit"
 require "stringio"
 require "active_support/key_generator"
+require "active_support/messages/rotation_configuration"
 
 class CookieStoreTest < ActionDispatch::IntegrationTest
   SessionKey = "_myapp_session"
   SessionSecret = "b3c631c314c0bbca50c1b2843150fe33"
   Generator = ActiveSupport::LegacyKeyGenerator.new(SessionSecret)
+  Rotations = ActiveSupport::Messages::RotationConfiguration.new
 
   Verifier = ActiveSupport::MessageVerifier.new(SessionSecret, digest: "SHA1")
   SignedBar = Verifier.generate(foo: "bar", session_id: SecureRandom.hex(16))
@@ -346,6 +348,8 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
       args[0] ||= {}
       args[0][:headers] ||= {}
       args[0][:headers]["action_dispatch.key_generator"] ||= Generator
+      args[0][:headers]["action_dispatch.cookies_rotations"] ||= Rotations
+
       super(path, *args)
     end
 
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 56013c5f95..487984cbd3 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,14 @@
+*   Add key rotation support to `MessageEncryptor` and `MessageVerifier`
+
+    This change introduces a `rotate` method to both the `MessageEncryptor` and
+    `MessageVerifier` classes. This method accepts the same arguments and
+    options as the given classes' constructor. The `encrypt_and_verify` method
+    for `MessageEncryptor` and the `verified` method for `MessageVerifier` also
+    accept an optional keyword argument `:on_rotation` block which is called
+    when a rotated instance is used to decrypt or verify the message.
+
+    *Michael J Coyne*
+
 *   Deprecate `Module#reachable?` method.
 
     *bogdanvlviv*
diff --git a/activesupport/lib/active_support/message_encryptor.rb b/activesupport/lib/active_support/message_encryptor.rb
index 27620f56be..003fb4c354 100644
--- a/activesupport/lib/active_support/message_encryptor.rb
+++ b/activesupport/lib/active_support/message_encryptor.rb
@@ -54,7 +54,37 @@ module ActiveSupport
   #
   # Then the messages can be verified and returned upto the expire time.
   # Thereafter, verifying returns +nil+.
+  #
+  # === Rotating keys
+  #
+  # This class also defines a +rotate+ method which can be used to rotate out
+  # encryption keys no longer in use.
+  #
+  # This method is called with an options hash where a +:cipher+ option and
+  # either a +:raw_key+ or +:secret+ option must be defined. If +:raw_key+ is
+  # defined, it is used directly for the underlying encryption function. If
+  # the +:secret+ option is defined, a +:salt+ option must also be defined and
+  # a +KeyGenerator+ instance will be used to derive a key using +:salt+. When
+  # +:secret+ is used, a +:key_generator+ option may also be defined allowing
+  # for custom +KeyGenerator+ instances. If CBC encryption is used a
+  # `:raw_signed_key` or a `:signed_salt` option must also be defined. A
+  # +:digest+ may also be defined when using CBC encryption. This method can be
+  # called multiple times and new encryptor instances will be added to the
+  # rotation stack on each call.
+  #
+  #   # Specifying the key used for encryption
+  #   crypt.rotate raw_key: old_aead_key, cipher: "aes-256-gcm"
+  #   crypt.rotate raw_key: old_cbc_key, raw_signed_key: old_cbc_sign_key, cipher: "aes-256-cbc", digest: "SHA1"
+  #
+  #   # Using a KeyGenerator instance with a secret and salt(s)
+  #   crypt.rotate secret: old_aead_secret, salt: old_aead_salt, cipher: "aes-256-gcm"
+  #   crypt.rotate secret: old_cbc_secret, salt: old_cbc_salt, signed_salt: old_cbc_signed_salt, cipher: "aes-256-cbc", digest: "SHA1"
+  #
+  #   # Specifying the key generator instance
+  #   crypt.rotate key_generator: old_key_gen, salt: old_salt, cipher: "aes-256-gcm"
   class MessageEncryptor
+    prepend Messages::Rotator::Encryptor
+
     class << self
       attr_accessor :use_authenticated_message_encryption #:nodoc:
 
@@ -126,7 +156,7 @@ module ActiveSupport
 
     # Decrypt and verify a message. We need to verify the message in order to
     # avoid padding attacks. Reference: https://www.limited-entropy.com/padding-oracle-attacks/.
-    def decrypt_and_verify(data, purpose: nil)
+    def decrypt_and_verify(data, purpose: nil, **)
       _decrypt(verifier.verify(data), purpose)
     end
 
diff --git a/activesupport/lib/active_support/message_verifier.rb b/activesupport/lib/active_support/message_verifier.rb
index 7110d6d2c9..0be13f6f03 100644
--- a/activesupport/lib/active_support/message_verifier.rb
+++ b/activesupport/lib/active_support/message_verifier.rb
@@ -4,6 +4,7 @@ require "base64"
 require_relative "core_ext/object/blank"
 require_relative "security_utils"
 require_relative "messages/metadata"
+require_relative "messages/rotator"
 
 module ActiveSupport
   # +MessageVerifier+ makes it easy to generate and verify messages which are
@@ -73,7 +74,36 @@ module ActiveSupport
   # Then the messages can be verified and returned upto the expire time.
   # Thereafter, the +verified+ method returns +nil+ while +verify+ raises
   # <tt>ActiveSupport::MessageVerifier::InvalidSignature</tt>.
+  #
+  # === Rotating keys
+  #
+  # This class also defines a +rotate+ method which can be used to rotate out
+  # verification keys no longer in use.
+  #
+  # This method is called with an options hash where a +:digest+ option and
+  # either a +:raw_key+ or +:secret+ option must be defined. If +:raw_key+ is
+  # defined, it is used directly for the underlying HMAC function. If the
+  # +:secret+ option is defined, a +:salt+ option must also be defined and a
+  # +KeyGenerator+ instance will be used to derive a key using +:salt+.  When
+  # +:secret+ is used, a +:key_generator+ option may also be defined allowing
+  # for custom +KeyGenerator+ instances. This method can be called multiple
+  # times and new verifier instances will be added to the rotation stack on
+  # each call.
+  #
+  #   # Specifying the key used for verification
+  #   @verifier.rotate raw_key: older_key, digest: "SHA1"
+  #
+  #   # Specify the digest
+  #   @verifier.rotate raw_key: old_key, digest: "SHA256"
+  #
+  #   # Using a KeyGenerator instance with a secret and salt
+  #   @verifier.rotate secret: old_secret, salt: old_salt, digest: "SHA1"
+  #
+  #   # Specifying the key generator instance
+  #   @verifier.rotate key_generator: old_key_gen, salt: old_salt, digest: "SHA256"
   class MessageVerifier
+    prepend Messages::Rotator::Verifier
+
     class InvalidSignature < StandardError; end
 
     def initialize(secret, options = {})
@@ -120,7 +150,7 @@ module ActiveSupport
     #
     #   incompatible_message = "test--dad7b06c94abba8d46a15fafaef56c327665d5ff"
     #   verifier.verified(incompatible_message) # => TypeError: incompatible marshal file format
-    def verified(signed_message, purpose: nil)
+    def verified(signed_message, purpose: nil, **)
       if valid_message?(signed_message)
         begin
           data = signed_message.split("--".freeze)[0]
@@ -145,8 +175,8 @@ module ActiveSupport
     #
     #   other_verifier = ActiveSupport::MessageVerifier.new 'd1ff3r3nt-s3Krit'
     #   other_verifier.verify(signed_message) # => ActiveSupport::MessageVerifier::InvalidSignature
-    def verify(signed_message, purpose: nil)
-      verified(signed_message, purpose: purpose) || raise(InvalidSignature)
+    def verify(*args)
+      verified(*args) || raise(InvalidSignature)
     end
 
     # Generates a signed message for the provided value.
diff --git a/activesupport/lib/active_support/messages/rotation_configuration.rb b/activesupport/lib/active_support/messages/rotation_configuration.rb
new file mode 100644
index 0000000000..12566bdb63
--- /dev/null
+++ b/activesupport/lib/active_support/messages/rotation_configuration.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module ActiveSupport
+  module Messages
+    class RotationConfiguration
+      attr_reader :signed, :encrypted
+
+      def initialize
+        @signed, @encrypted = [], []
+      end
+
+      def rotate(kind = nil, **options)
+        case kind
+        when :signed
+          @signed << options
+        when :encrypted
+          @encrypted << options
+        else
+          rotate :signed, options
+          rotate :encrypted, options
+        end
+      end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/messages/rotator.rb b/activesupport/lib/active_support/messages/rotator.rb
new file mode 100644
index 0000000000..21ae643138
--- /dev/null
+++ b/activesupport/lib/active_support/messages/rotator.rb
@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+module ActiveSupport
+  module Messages
+    module Rotator # :nodoc:
+      def initialize(*args)
+        super
+
+        @rotations = []
+      end
+
+      def rotate(*args)
+        @rotations << create_rotation(*args)
+      end
+
+      module Encryptor
+        include Rotator
+
+        def decrypt_and_verify(*args, on_rotation: nil, **options)
+          super
+        rescue MessageEncryptor::InvalidMessage, MessageVerifier::InvalidSignature
+          run_rotations(on_rotation) { |encryptor| encryptor.decrypt_and_verify(*args, options) } || raise
+        end
+
+        private
+          def create_rotation(raw_key: nil, raw_signed_key: nil, **options)
+            self.class.new \
+              raw_key || extract_key(options),
+              raw_signed_key || extract_signing_key(options),
+              options.slice(:cipher, :digest, :serializer)
+          end
+
+          def extract_key(cipher:, salt:, key_generator: nil, secret: nil, **)
+            key_generator ||= key_generator_for(secret)
+            key_generator.generate_key(salt, self.class.key_len(cipher))
+          end
+
+          def extract_signing_key(cipher:, signed_salt: nil, key_generator: nil, secret: nil, **)
+            if cipher.downcase.end_with?("cbc")
+              raise ArgumentError, "missing signed_salt for signing key generation" unless signed_salt
+
+              key_generator ||= key_generator_for(secret)
+              key_generator.generate_key(signed_salt)
+            end
+          end
+      end
+
+      module Verifier
+        include Rotator
+
+        def verified(*args, on_rotation: nil, **options)
+          super || run_rotations(on_rotation) { |verifier| verifier.verified(*args, options) }
+        end
+
+        private
+          def create_rotation(raw_key: nil, digest: nil, serializer: nil, **options)
+            self.class.new(raw_key || extract_key(options), digest: digest, serializer: serializer)
+          end
+
+          def extract_key(key_generator: nil, secret: nil, salt:)
+            key_generator ||= key_generator_for(secret)
+            key_generator.generate_key(salt)
+          end
+      end
+
+      private
+        def key_generator_for(secret)
+          ActiveSupport::KeyGenerator.new(secret, iterations: 1000)
+        end
+
+        def run_rotations(on_rotation)
+          @rotations.find do |rotation|
+            if message = yield(rotation) rescue next
+              on_rotation.call if on_rotation
+              return message
+            end
+          end
+        end
+    end
+  end
+end
diff --git a/activesupport/test/message_encryptor_test.rb b/activesupport/test/message_encryptor_test.rb
index 1fbe655642..17baf3550b 100644
--- a/activesupport/test/message_encryptor_test.rb
+++ b/activesupport/test/message_encryptor_test.rb
@@ -115,6 +115,124 @@ class MessageEncryptorTest < ActiveSupport::TestCase
     assert_equal "Ruby on Rails", encryptor.decrypt_and_verify(encrypted_message)
   end
 
+  def test_with_rotated_raw_key
+    old_raw_key = SecureRandom.random_bytes(32)
+    old_encryptor = ActiveSupport::MessageEncryptor.new(old_raw_key, cipher: "aes-256-gcm")
+    old_message = old_encryptor.encrypt_and_sign("message encrypted with old raw key")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret, cipher: "aes-256-gcm")
+    encryptor.rotate raw_key: old_raw_key, cipher: "aes-256-gcm"
+
+    assert_equal "message encrypted with old raw key", encryptor.decrypt_and_verify(old_message)
+  end
+
+  def test_with_rotated_secret_and_salt
+    old_secret, old_salt = SecureRandom.random_bytes(32), "old salt"
+    old_raw_key = ActiveSupport::KeyGenerator.new(old_secret, iterations: 1000).generate_key(old_salt, 32)
+
+    old_encryptor = ActiveSupport::MessageEncryptor.new(old_raw_key, cipher: "aes-256-gcm")
+    old_message = old_encryptor.encrypt_and_sign("message encrypted with old secret and salt")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret, cipher: "aes-256-gcm")
+    encryptor.rotate secret: old_secret, salt: old_salt, cipher: "aes-256-gcm"
+
+    assert_equal "message encrypted with old secret and salt", encryptor.decrypt_and_verify(old_message)
+  end
+
+  def test_with_rotated_key_generator
+    old_key_gen, old_salt = ActiveSupport::KeyGenerator.new(SecureRandom.random_bytes(32), iterations: 256), "old salt"
+
+    old_raw_key = old_key_gen.generate_key(old_salt, 32)
+    old_encryptor = ActiveSupport::MessageEncryptor.new(old_raw_key, cipher: "aes-256-gcm")
+    old_message = old_encryptor.encrypt_and_sign("message encrypted with old key generator and salt")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret, cipher: "aes-256-gcm")
+    encryptor.rotate key_generator: old_key_gen, salt: old_salt, cipher: "aes-256-gcm"
+
+    assert_equal "message encrypted with old key generator and salt", encryptor.decrypt_and_verify(old_message)
+  end
+
+  def test_with_rotated_aes_cbc_encryptor_with_raw_keys
+    old_raw_key, old_raw_signed_key = SecureRandom.random_bytes(32), SecureRandom.random_bytes(16)
+
+    old_encryptor = ActiveSupport::MessageEncryptor.new(old_raw_key, old_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1")
+    old_message = old_encryptor.encrypt_and_sign("message encrypted with old raw keys")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret)
+    encryptor.rotate raw_key: old_raw_key, raw_signed_key: old_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1"
+
+    assert_equal "message encrypted with old raw keys", encryptor.decrypt_and_verify(old_message)
+  end
+
+  def test_with_rotated_aes_cbc_encryptor_with_secret_and_salts
+    old_secret, old_salt, old_signed_salt = SecureRandom.random_bytes(32), "old salt", "old signed salt"
+
+    old_key_gen = ActiveSupport::KeyGenerator.new(old_secret, iterations: 1000)
+    old_raw_key = old_key_gen.generate_key(old_salt, 32)
+    old_raw_signed_key = old_key_gen.generate_key(old_signed_salt)
+
+    old_encryptor = ActiveSupport::MessageEncryptor.new(old_raw_key, old_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1")
+    old_message = old_encryptor.encrypt_and_sign("message encrypted with old secret and salts")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret)
+    encryptor.rotate secret: old_secret, salt: old_salt, signed_salt: old_signed_salt, cipher: "aes-256-cbc", digest: "SHA1"
+
+    assert_equal "message encrypted with old secret and salts", encryptor.decrypt_and_verify(old_message)
+  end
+
+  def test_with_rotating_multiple_encryptors
+    older_raw_key, older_raw_signed_key = SecureRandom.random_bytes(32), SecureRandom.random_bytes(16)
+    old_raw_key, old_raw_signed_key = SecureRandom.random_bytes(32), SecureRandom.random_bytes(16)
+
+    older_encryptor = ActiveSupport::MessageEncryptor.new(older_raw_key, older_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1")
+    older_message = older_encryptor.encrypt_and_sign("message encrypted with older raw key")
+
+    old_encryptor = ActiveSupport::MessageEncryptor.new(old_raw_key, old_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1")
+    old_message = old_encryptor.encrypt_and_sign("message encrypted with old raw key")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret)
+    encryptor.rotate raw_key: old_raw_key, raw_signed_key: old_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1"
+    encryptor.rotate raw_key: older_raw_key, raw_signed_key: older_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1"
+
+    assert_equal "encrypted message", encryptor.decrypt_and_verify(encryptor.encrypt_and_sign("encrypted message"))
+    assert_equal "message encrypted with old raw key", encryptor.decrypt_and_verify(old_message)
+    assert_equal "message encrypted with older raw key", encryptor.decrypt_and_verify(older_message)
+  end
+
+  def test_on_rotation_instance_callback_is_called_and_returns_modified_messages
+    callback_ran, message = nil, nil
+
+    older_raw_key, older_raw_signed_key = SecureRandom.random_bytes(32), SecureRandom.random_bytes(16)
+    old_raw_key, old_raw_signed_key = SecureRandom.random_bytes(32), SecureRandom.random_bytes(16)
+
+    older_encryptor = ActiveSupport::MessageEncryptor.new(older_raw_key, older_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1")
+    older_message = older_encryptor.encrypt_and_sign(encoded: "message")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret)
+    encryptor.rotate raw_key: old_raw_key, raw_signed_key: old_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1"
+    encryptor.rotate raw_key: older_raw_key, raw_signed_key: older_raw_signed_key, cipher: "aes-256-cbc", digest: "SHA1"
+
+    message = encryptor.decrypt_and_verify(older_message, on_rotation: proc { callback_ran = true })
+
+    assert callback_ran, "callback was ran"
+    assert_equal({ encoded: "message" }, message)
+  end
+
+  def test_with_rotated_metadata
+    old_secret, old_salt = SecureRandom.random_bytes(32), "old salt"
+    old_raw_key = ActiveSupport::KeyGenerator.new(old_secret, iterations: 1000).generate_key(old_salt, 32)
+
+    old_encryptor = ActiveSupport::MessageEncryptor.new(old_raw_key, cipher: "aes-256-gcm")
+    old_message = old_encryptor.encrypt_and_sign(
+      "message encrypted with old secret, salt, and metadata", purpose: "rotation")
+
+    encryptor = ActiveSupport::MessageEncryptor.new(@secret, cipher: "aes-256-gcm")
+    encryptor.rotate secret: old_secret, salt: old_salt, cipher: "aes-256-gcm"
+
+    assert_equal "message encrypted with old secret, salt, and metadata",
+      encryptor.decrypt_and_verify(old_message, purpose: "rotation")
+  end
+
   private
     def assert_aead_not_decrypted(encryptor, value)
       assert_raise(ActiveSupport::MessageEncryptor::InvalidMessage) do
diff --git a/activesupport/test/message_verifier_test.rb b/activesupport/test/message_verifier_test.rb
index fbeafca203..3079c48c02 100644
--- a/activesupport/test/message_verifier_test.rb
+++ b/activesupport/test/message_verifier_test.rb
@@ -20,6 +20,7 @@ class MessageVerifierTest < ActiveSupport::TestCase
   def setup
     @verifier = ActiveSupport::MessageVerifier.new("Hey, I'm a secret!")
     @data = { some: "data", now: Time.utc(2010) }
+    @secret = SecureRandom.random_bytes(32)
   end
 
   def test_valid_message
@@ -90,6 +91,95 @@ class MessageVerifierTest < ActiveSupport::TestCase
     signed_message = "BAh7BzoJc29tZUkiCWRhdGEGOgZFVDoIbm93SXU6CVRpbWUNIIAbgAAAAAAHOgtvZmZzZXRpADoJem9uZUkiCFVUQwY7BkY=--d03c52c91dfe4ccc5159417c660461bcce005e96"
     assert_equal @data, @verifier.verify(signed_message)
   end
+
+  def test_with_rotated_raw_key
+    old_raw_key = SecureRandom.random_bytes(32)
+
+    old_verifier = ActiveSupport::MessageVerifier.new(old_raw_key, digest: "SHA1")
+    old_message = old_verifier.generate("message verified with old raw key")
+
+    verifier = ActiveSupport::MessageVerifier.new(@secret, digest: "SHA1")
+    verifier.rotate raw_key: old_raw_key, digest: "SHA1"
+
+    assert_equal "message verified with old raw key", verifier.verified(old_message)
+  end
+
+  def test_with_rotated_secret_and_salt
+    old_secret, old_salt = SecureRandom.random_bytes(32), "old salt"
+
+    old_raw_key = ActiveSupport::KeyGenerator.new(old_secret, iterations: 1000).generate_key(old_salt)
+    old_verifier = ActiveSupport::MessageVerifier.new(old_raw_key, digest: "SHA1")
+    old_message = old_verifier.generate("message verified with old secret and salt")
+
+    verifier = ActiveSupport::MessageVerifier.new(@secret, digest: "SHA1")
+    verifier.rotate secret: old_secret, salt: old_salt, digest: "SHA1"
+
+    assert_equal "message verified with old secret and salt", verifier.verified(old_message)
+  end
+
+  def test_with_rotated_key_generator
+    old_key_gen, old_salt = ActiveSupport::KeyGenerator.new(SecureRandom.random_bytes(32), iterations: 256), "old salt"
+
+    old_raw_key = old_key_gen.generate_key(old_salt)
+    old_verifier = ActiveSupport::MessageVerifier.new(old_raw_key, digest: "SHA1")
+    old_message = old_verifier.generate("message verified with old key generator and salt")
+
+    verifier = ActiveSupport::MessageVerifier.new(@secret, digest: "SHA1")
+    verifier.rotate key_generator: old_key_gen, salt: old_salt, digest: "SHA1"
+
+    assert_equal "message verified with old key generator and salt", verifier.verified(old_message)
+  end
+
+  def test_with_rotating_multiple_verifiers
+    old_raw_key, older_raw_key = SecureRandom.random_bytes(32), SecureRandom.random_bytes(32)
+
+    old_verifier = ActiveSupport::MessageVerifier.new(old_raw_key, digest: "SHA256")
+    old_message = old_verifier.generate("message verified with old raw key")
+
+    older_verifier = ActiveSupport::MessageVerifier.new(older_raw_key, digest: "SHA1")
+    older_message = older_verifier.generate("message verified with older raw key")
+
+    verifier = ActiveSupport::MessageVerifier.new("new secret", digest: "SHA512")
+    verifier.rotate raw_key: old_raw_key, digest: "SHA256"
+    verifier.rotate raw_key: older_raw_key, digest: "SHA1"
+
+    assert_equal "verified message", verifier.verified(verifier.generate("verified message"))
+    assert_equal "message verified with old raw key", verifier.verified(old_message)
+    assert_equal "message verified with older raw key", verifier.verified(older_message)
+  end
+
+  def test_on_rotation_keyword_block_is_called_and_verified_returns_message
+    callback_ran, message = nil, nil
+
+    old_raw_key, older_raw_key = SecureRandom.random_bytes(32), SecureRandom.random_bytes(32)
+
+    older_verifier = ActiveSupport::MessageVerifier.new(older_raw_key, digest: "SHA1")
+    older_message = older_verifier.generate(encoded: "message")
+
+    verifier = ActiveSupport::MessageVerifier.new("new secret", digest: "SHA512")
+    verifier.rotate raw_key: old_raw_key, digest: "SHA256"
+    verifier.rotate raw_key: older_raw_key, digest: "SHA1"
+
+    message = verifier.verified(older_message, on_rotation: proc { callback_ran = true })
+
+    assert callback_ran, "callback was ran"
+    assert_equal({ encoded: "message" }, message)
+  end
+
+  def test_with_rotated_metadata
+    old_secret, old_salt = SecureRandom.random_bytes(32), "old salt"
+
+    old_raw_key = ActiveSupport::KeyGenerator.new(old_secret, iterations: 1000).generate_key(old_salt)
+    old_verifier = ActiveSupport::MessageVerifier.new(old_raw_key, digest: "SHA1")
+    old_message = old_verifier.generate(
+      "message verified with old secret, salt, and metadata", purpose: "rotation")
+
+    verifier = ActiveSupport::MessageVerifier.new(@secret, digest: "SHA1")
+    verifier.rotate secret: old_secret, salt: old_salt, digest: "SHA1"
+
+    assert_equal "message verified with old secret, salt, and metadata",
+      verifier.verified(old_message, purpose: "rotation")
+  end
 end
 
 class MessageVerifierMetadataTest < ActiveSupport::TestCase
diff --git a/activesupport/test/messages/rotation_configuration_test.rb b/activesupport/test/messages/rotation_configuration_test.rb
new file mode 100644
index 0000000000..41d938e119
--- /dev/null
+++ b/activesupport/test/messages/rotation_configuration_test.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+require "active_support/messages/rotation_configuration"
+
+class MessagesRotationConfiguration < ActiveSupport::TestCase
+  def setup
+    @config = ActiveSupport::Messages::RotationConfiguration.new
+  end
+
+  def test_signed_configurations
+    @config.rotate :signed, secret: "older secret", salt: "salt", digest: "SHA1"
+    @config.rotate :signed, secret: "old secret", salt: "salt", digest: "SHA256"
+
+    assert_equal [{
+      secret: "older secret", salt: "salt", digest: "SHA1"
+    }, {
+      secret: "old secret", salt: "salt", digest: "SHA256"
+    }], @config.signed
+  end
+
+  def test_encrypted_configurations
+    @config.rotate :encrypted, raw_key: "old raw key", cipher: "aes-256-gcm"
+
+    assert_equal [{
+      raw_key: "old raw key", cipher: "aes-256-gcm"
+    }], @config.encrypted
+  end
+
+  def test_rotate_without_kind
+    @config.rotate secret: "older secret", salt: "salt", digest: "SHA1"
+    @config.rotate raw_key: "old raw key", cipher: "aes-256-gcm"
+
+    expected = [{
+      secret: "older secret", salt: "salt", digest: "SHA1"
+    }, {
+      raw_key: "old raw key", cipher: "aes-256-gcm"
+    }]
+
+    assert_equal expected, @config.encrypted
+    assert_equal expected, @config.signed
+  end
+end
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 1c720ad82f..86c8364d83 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -487,6 +487,17 @@ Defaults to `'signed cookie'`.
   authenticated encrypted cookie salt. Defaults to `'authenticated encrypted
   cookie'`.
 
+* `config.action_dispatch.encrypted_cookie_cipher` sets the cipher to be
+  used for encrypted cookies. This defaults to `"aes-256-gcm"`.
+
+* `config.action_dispatch.signed_cookie_digest` sets the digest to be
+  used for signed cookies. This defaults to `"SHA1"`.
+
+* `config.action_dispatch.cookies_rotations` is set to an instance of
+  [RotationConfiguration](http://api.rubyonrails.org/classes/ActiveSupport/RotationConfiguration.html).
+  It provides an interface for rotating keys, salts, ciphers, and
+  digests for encrypted and signed cookies.
+
 * `config.action_dispatch.perform_deep_munge` configures whether `deep_munge`
   method should be performed on the parameters. See [Security Guide](security.html#unsafe-query-generation)
   for more information. It defaults to `true`.
diff --git a/guides/source/security.md b/guides/source/security.md
index 0b2d8de0fb..b0b71cad7d 100644
--- a/guides/source/security.md
+++ b/guides/source/security.md
@@ -85,37 +85,129 @@ This will also be a good idea, if you modify the structure of an object and old
 
 * _Critical data should not be stored in session_. If the user clears their cookies or closes the browser, they will be lost. And with a client-side session storage, the user can read the data.
 
-### Session Storage
+### Encrypted Session Storage
 
 NOTE: _Rails provides several storage mechanisms for the session hashes. The most important is `ActionDispatch::Session::CookieStore`._
 
-Rails 2 introduced a new default session storage, CookieStore. CookieStore saves the session hash directly in a cookie on the client-side. The server retrieves the session hash from the cookie and eliminates the need for a session ID. That will greatly increase the speed of the application, but it is a controversial storage option and you have to think about the security implications of it:
+The `CookieStore` saves the session hash directly in a cookie on the
+client-side. The server retrieves the session hash from the cookie and
+eliminates the need for a session ID. That will greatly increase the
+speed of the application, but it is a controversial storage option and
+you have to think about the security implications and storage
+limitations of it:
+
+* Cookies imply a strict size limit of 4kB. This is fine as you should
+  not store large amounts of data in a session anyway, as described
+  before. Storing the current user's database id in a session is common
+  practice.
+
+* Session cookies do not invalidate themselves and can be maliciously
+  reused. It may be a good idea to have your application invalidate old
+  session cookies using a stored timestamp.
+
+The `CookieStore` uses the
+[encrypted](http://api.rubyonrails.org/classes/ActionDispatch/Cookies/ChainedCookieJars.html#method-i-encrypted)
+cookie jar to provide a secure, encrypted location to store session
+data. Cookie-based sessions thus provide both integrity as well as
+confidentiality to their contents. The encryption key, as well as the
+verification key used for
+[signed](http://api.rubyonrails.org/classes/ActionDispatch/Cookies/ChainedCookieJars.html#method-i-signed)
+cookies, is derived from the `secret_key_base` configuration value.
+
+As of Rails 5.2 encrypted cookies and sessions are protected using AES
+GCM encryption. This form of encryption is a type of Authenticated
+Encryption and couples authentication and encryption in single step
+while also producing shorter ciphertexts as compared to other
+algorithms previously used. The key for cookies encrypted with AES GCM
+are derived using a salt value defined by the
+`config.action_dispatch.authenticated_encrypted_cookie_salt`
+configuration value.
+
+Prior to this version, encrypted cookies were secured using AES in CBC
+mode with HMAC using SHA1 for authentication. The keys for this type of
+encryption and for HMAC verification were derived via the salts defined
+by `config.action_dispatch.encrypted_cookie_salt` and
+`config.action_dispatch.encrypted_signed_cookie_salt` respectively.
+
+Prior to Rails version 4 in both versions 2 and 3, session cookies were
+protected using only HMAC verification. As such, these session cookies
+only provided integrity to their content because the actual session data
+was stored in plaintext encoded as base64. This is how `signed` cookies
+work in the current version of Rails. These kinds of cookies are still
+useful for protecting the integrity of certain client-stored data and
+information.
+
+__Do not use a trivial secret for the `secret_key_base`, i.e. a word
+from a dictionary, or one which is shorter than 30 characters! Instead
+use `rails secret` to generate secret keys!__
+
+It is also important to use different salt values for encrypted and
+signed cookies. Using the same value for different salt configuration
+values may lead to the same derived key being used for different
+security features which in turn may weaken the strength of the key.
 
-* Cookies imply a strict size limit of 4kB. This is fine as you should not store large amounts of data in a session anyway, as described before. _Storing the current user's database id in a session is usually ok_.
+In test and development applications get a `secret_key_base` derived from the app name. Other environments must use a random key present in `config/credentials.yml.enc`, shown here in its decrypted state:
 
-* The client can see everything you store in a session, because it is stored in clear-text (actually Base64-encoded, so not encrypted). So, of course, _you don't want to store any secrets here_. To prevent session hash tampering, a digest is calculated from the session with a server-side secret (`secrets.secret_token`) and inserted into the end of the cookie.
+    secret_key_base: 492f...
 
-In Rails 4, encrypted cookies through AES in CBC mode with HMAC using SHA1 for
-verification was introduced. This prevents the user from accessing and tampering
-the content of the cookie. Thus the session becomes a more secure place to store
-data. The encryption is performed using a server-side `secret_key_base`.
-Two salts are used when deriving keys for encryption and verification. These
-salts are set via the `config.action_dispatch.encrypted_cookie_salt` and
-`config.action_dispatch.encrypted_signed_cookie_salt` configuration values.
+If you have received an application where the secret was exposed (e.g. an application whose source was shared), strongly consider changing the secret.
 
-Rails 5.2 uses AES-GCM for the encryption which couples authentication
-and encryption in one faster step and produces shorter ciphertexts.
+### Rotating Keys for Encrypted and Signed Cookies
 
-Encrypted cookies are automatically upgraded if the
-`config.action_dispatch.use_authenticated_cookie_encryption` is enabled.
+It is possible to rotate the `secret_key_base` as well as the salts,
+ciphers, and digests used for both encrypted and signed cookies. Rotating
+the `secret_key_base` is necessary if the value was exposed or leaked.
+It is also useful to rotate this value for other more benign reasons,
+such as an employee leaving your organization or changing hosting
+environments.
 
-_Do not use a trivial secret, i.e. a word from a dictionary, or one which is shorter than 30 characters! Instead use `rails secret` to generate secret keys!_
+Key rotations can be defined through the
+`config.action_dispatch.cookies_rotations` configuration value. This
+value is set to an instance of
+[RotationConfiguration](http://api.rubyonrails.org/classes/ActiveSupport/RotationConfiguration.html)
+which provides an interface for rotating signed and encrypted cookie
+keys, salts, digests, and ciphers.
 
-In test and development applications get a `secret_key_base` derived from the app name. Other environments must use a random key present in `config/credentials.yml.enc`, shown here in its decrypted state:
+For example, suppose we want to rotate out an old `secret_key_base`, we
+can define a signed and encrypted key rotation as follows:
 
-    secret_key_base: 492f...
+```ruby
+config.action_dispatch.cookies_rotations.rotate :encrypted,
+  cipher: "aes-256-gcm",
+  secret: Rails.application.credentials.old_secret_key_base,
+  salt: config.action_dispatch.authenticated_encrypted_cookie_salt
 
-If you have received an application where the secret was exposed (e.g. an application whose source was shared), strongly consider changing the secret.
+config.action_dispatch.cookies_rotations.rotate :signed,
+  digest: "SHA1",
+  secret: Rails.application.credentials.old_secret_key_base,
+  salt: config.action_dispatch.signed_cookie_salt
+```
+
+Multiple rotations are possible by calling `rotate` multiple times. For
+example, suppose we want to use SHA512 for signed cookies while rotating
+out SHA256 and SHA1 digests using the same `secret_key_base`
+
+```ruby
+config.action_dispatch.signed_cookie_digest = "SHA512"
+
+config.action_dispatch.cookies_rotations.rotate :signed,
+  digest: "SHA256",
+  secret: Rails.application.credentials.secret_key_base,
+  salt: config.action_dispatch.signed_cookie_salt
+
+config.action_dispatch.cookies_rotations.rotate :signed,
+  digest: "SHA1",
+  secret: Rails.application.credentials.secret_key_base,
+  salt: config.action_dispatch.signed_cookie_salt
+```
+
+For more details on key rotation with encrypted and signed messages as
+well as the various options the `rotate` method accepts, please refer to
+the
+[MessageEncryptor API](api.rubyonrails.org/classes/ActiveSupport/MessageEncryptor.html)
+and
+[MessageVerifier API](api.rubyonrails.org/classes/ActiveSupport/MessageVerifier.html)
+documentation.
 
 ### Replay Attacks for CookieStore Sessions
 
diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index abfec90b6d..24f5eeae87 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -259,8 +259,12 @@ module Rails
           "action_dispatch.encrypted_cookie_salt" => config.action_dispatch.encrypted_cookie_salt,
           "action_dispatch.encrypted_signed_cookie_salt" => config.action_dispatch.encrypted_signed_cookie_salt,
           "action_dispatch.authenticated_encrypted_cookie_salt" => config.action_dispatch.authenticated_encrypted_cookie_salt,
+          "action_dispatch.use_authenticated_cookie_encryption" => config.action_dispatch.use_authenticated_cookie_encryption,
+          "action_dispatch.encrypted_cookie_cipher" => config.action_dispatch.encrypted_cookie_cipher,
+          "action_dispatch.signed_cookie_digest" => config.action_dispatch.signed_cookie_digest,
           "action_dispatch.cookies_serializer" => config.action_dispatch.cookies_serializer,
-          "action_dispatch.cookies_digest" => config.action_dispatch.cookies_digest
+          "action_dispatch.cookies_digest" => config.action_dispatch.cookies_digest,
+          "action_dispatch.cookies_rotations" => config.action_dispatch.cookies_rotations
         )
       end
     end
diff --git a/railties/test/application/middleware/cookies_test.rb b/railties/test/application/middleware/cookies_test.rb
index 23f1ec3e35..932a6d0e77 100644
--- a/railties/test/application/middleware/cookies_test.rb
+++ b/railties/test/application/middleware/cookies_test.rb
@@ -1,10 +1,12 @@
 # frozen_string_literal: true
 
 require "isolation/abstract_unit"
+require "rack/test"
 
 module ApplicationTests
   class CookiesTest < ActiveSupport::TestCase
     include ActiveSupport::Testing::Isolation
+    include Rack::Test::Methods
 
     def new_app
       File.expand_path("#{app_path}/../new_app")
@@ -15,6 +17,10 @@ module ApplicationTests
       FileUtils.rm_rf("#{app_path}/config/environments")
     end
 
+    def app
+      Rails.application
+    end
+
     def teardown
       teardown_app
       FileUtils.rm_rf(new_app) if File.directory?(new_app)
@@ -44,5 +50,142 @@ module ApplicationTests
       require "#{app_path}/config/environment"
       assert_equal false, ActionDispatch::Cookies::CookieJar.always_write_cookie
     end
+
+    test "signed cookies with SHA512 digest and rotated out SHA256 and SHA1 digests" do
+      key_gen_sha1 = ActiveSupport::KeyGenerator.new("legacy sha1 secret", iterations: 1000)
+      key_gen_sha256 = ActiveSupport::KeyGenerator.new("legacy sha256 secret", iterations: 1000)
+
+      verifer_sha1 = ActiveSupport::MessageVerifier.new(key_gen_sha1.generate_key("sha1 salt"), digest: :SHA1)
+      verifer_sha256 = ActiveSupport::MessageVerifier.new(key_gen_sha256.generate_key("sha256 salt"), digest: :SHA256)
+
+      app_file "config/routes.rb", <<-RUBY
+        Rails.application.routes.draw do
+          get  ':controller(/:action)'
+          post ':controller(/:action)'
+        end
+      RUBY
+
+      controller :foo, <<-RUBY
+        class FooController < ActionController::Base
+          protect_from_forgery with: :null_session
+
+          def write_raw_cookie_sha1
+            cookies[:signed_cookie] = "#{verifer_sha1.generate("signed cookie")}"
+            head :ok
+          end
+
+          def write_raw_cookie_sha256
+            cookies[:signed_cookie] = "#{verifer_sha256.generate("signed cookie")}"
+            head :ok
+          end
+
+          def read_signed
+            render plain: cookies.signed[:signed_cookie].inspect
+          end
+
+          def read_raw_cookie
+            render plain: cookies[:signed_cookie]
+          end
+        end
+      RUBY
+
+      add_to_config <<-RUBY
+        config.action_dispatch.cookies_rotations.rotate :signed,
+          digest: "SHA1", secret: "legacy sha1 secret", salt: "sha1 salt"
+
+        config.action_dispatch.cookies_rotations.rotate :signed,
+          digest: "SHA256", secret: "legacy sha256 secret", salt: "sha256 salt"
+
+        config.action_dispatch.signed_cookie_digest = "SHA512"
+        config.action_dispatch.signed_cookie_salt = "sha512 salt"
+      RUBY
+
+      require "#{app_path}/config/environment"
+
+      verifer_sha512 = ActiveSupport::MessageVerifier.new(app.key_generator.generate_key("sha512 salt"), digest: :SHA512)
+
+      get "/foo/write_raw_cookie_sha1"
+      get "/foo/read_signed"
+      assert_equal "signed cookie".inspect, last_response.body
+
+      get "/foo/read_raw_cookie"
+      assert_equal "signed cookie", verifer_sha512.verify(last_response.body)
+
+      get "/foo/write_raw_cookie_sha256"
+      get "/foo/read_signed"
+      assert_equal "signed cookie".inspect, last_response.body
+
+      get "/foo/read_raw_cookie"
+      assert_equal "signed cookie", verifer_sha512.verify(last_response.body)
+    end
+
+    test "encrypted cookies with multiple rotated out ciphers" do
+      key_gen_one = ActiveSupport::KeyGenerator.new("legacy secret one", iterations: 1000)
+      key_gen_two = ActiveSupport::KeyGenerator.new("legacy secret two", iterations: 1000)
+
+      encryptor_one = ActiveSupport::MessageEncryptor.new(key_gen_one.generate_key("salt one", 32), cipher: "aes-256-gcm")
+      encryptor_two = ActiveSupport::MessageEncryptor.new(key_gen_two.generate_key("salt two", 32), cipher: "aes-256-gcm")
+
+      app_file "config/routes.rb", <<-RUBY
+        Rails.application.routes.draw do
+          get  ':controller(/:action)'
+          post ':controller(/:action)'
+        end
+      RUBY
+
+      controller :foo, <<-RUBY
+        class FooController < ActionController::Base
+          protect_from_forgery with: :null_session
+
+          def write_raw_cookie_one
+            cookies[:encrypted_cookie] = "#{encryptor_one.encrypt_and_sign("encrypted cookie")}"
+            head :ok
+          end
+
+          def write_raw_cookie_two
+            cookies[:encrypted_cookie] = "#{encryptor_two.encrypt_and_sign("encrypted cookie")}"
+            head :ok
+          end
+
+          def read_encrypted
+            render plain: cookies.encrypted[:encrypted_cookie].inspect
+          end
+
+          def read_raw_cookie
+            render plain: cookies[:encrypted_cookie]
+          end
+        end
+      RUBY
+
+      add_to_config <<-RUBY
+        config.action_dispatch.use_authenticated_cookie_encryption = true
+        config.action_dispatch.encrypted_cookie_cipher = "aes-256-gcm"
+        config.action_dispatch.authenticated_encrypted_cookie_salt = "salt"
+
+        config.action_dispatch.cookies_rotations.rotate :encrypted,
+          cipher: "aes-256-gcm", secret: "legacy secret one", salt: "salt one"
+
+        config.action_dispatch.cookies_rotations.rotate :encrypted,
+          cipher: "aes-256-gcm", secret: "legacy secret two", salt: "salt two"
+      RUBY
+
+      require "#{app_path}/config/environment"
+
+      encryptor = ActiveSupport::MessageEncryptor.new(app.key_generator.generate_key("salt", 32), cipher: "aes-256-gcm")
+
+      get "/foo/write_raw_cookie_one"
+      get "/foo/read_encrypted"
+      assert_equal "encrypted cookie".inspect, last_response.body
+
+      get "/foo/read_raw_cookie"
+      assert_equal "encrypted cookie", encryptor.decrypt_and_verify(last_response.body)
+
+      get "/foo/write_raw_cookie_sha256"
+      get "/foo/read_encrypted"
+      assert_equal "encrypted cookie".inspect, last_response.body
+
+      get "/foo/read_raw_cookie"
+      assert_equal "encrypted cookie", encryptor.decrypt_and_verify(last_response.body)
+    end
   end
 end