[CHEF-5356-gcm] Chef::EncryptedDataBagItem Version3 implementation using GCM

3 files changed, 134 insertions, 11 deletions

diff --git a/lib/chef/encrypted_data_bag_item/decryptor.rb b/lib/chef/encrypted_data_bag_item/decryptor.rb
index 69b8d62e3b..82d04c0d67 100644
--- a/lib/chef/encrypted_data_bag_item/decryptor.rb
+++ b/lib/chef/encrypted_data_bag_item/decryptor.rb
@@ -45,6 +45,8 @@ class Chef::EncryptedDataBagItem
       format_version = format_version_of(encrypted_value)
       assert_format_version_acceptable!(format_version)
       case format_version
+      when 3
+        Version3Decryptor.new(encrypted_value, key)
       when 2
         Version2Decryptor.new(encrypted_value, key)
       when 1
@@ -83,6 +85,11 @@ class Chef::EncryptedDataBagItem
         @key = key
       end
 
+      # Returns the used decryption algorithm
+      def algorithm
+        ALGORITHM
+      end
+
       def for_decrypted_item
         YAML.load(decrypted_data)
       end
@@ -102,7 +109,7 @@ class Chef::EncryptedDataBagItem
 
       def openssl_decryptor
         @openssl_decryptor ||= begin
-          d = OpenSSL::Cipher::Cipher.new(ALGORITHM)
+          d = OpenSSL::Cipher::Cipher.new(algorithm)
           d.decrypt
           d.pkcs5_keyivgen(key)
           d
@@ -110,7 +117,7 @@ class Chef::EncryptedDataBagItem
       end
     end
 
-    class Version1Decryptor
+    class Version1Decryptor < Version0Decryptor
 
       attr_reader :encrypted_data
       attr_reader :key
@@ -149,8 +156,9 @@ class Chef::EncryptedDataBagItem
       def openssl_decryptor
         @openssl_decryptor ||= begin
           assert_valid_cipher!
-          d = OpenSSL::Cipher::Cipher.new(ALGORITHM)
+          d = OpenSSL::Cipher::Cipher.new(algorithm)
           d.decrypt
+          # We must set key before iv: https://bugs.ruby-lang.org/issues/8221
           d.key = Digest::SHA256.digest(key)
           d.iv = iv
           d
@@ -159,11 +167,11 @@ class Chef::EncryptedDataBagItem
 
       def assert_valid_cipher!
         # In the future, chef may support configurable ciphers. For now, only
-        # aes-256-cbc is supported.
+        # aes-256-cbc and aes-256-gcm are supported.
         requested_cipher = @encrypted_data["cipher"]
-        unless requested_cipher == ALGORITHM
+        unless requested_cipher == algorithm
           raise UnsupportedCipher,
-            "Cipher '#{requested_cipher}' is not supported by this version of Chef. Available ciphers: ['#{ALGORITHM}']"
+            "Cipher '#{requested_cipher}' is not supported by this version of Chef. Available ciphers: ['#{ALGORITHM}', '#{AEAD_ALGORITHM}']"
         end
       end
     end
@@ -197,5 +205,32 @@ class Chef::EncryptedDataBagItem
         valid == 0
       end
     end
+
+    class Version3Decryptor < Version1Decryptor
+
+      # Returns the used decryption algorithm
+      def algorithm
+        AEAD_ALGORITHM
+      end
+
+      def auth_tag
+        auth_tag_b64 = @encrypted_data["auth_tag"]
+        if auth_tag_b64.nil?
+          raise DecryptionFailure, "Error decrypting data bag value: invalid authentication tag. Most likely the data is corrupted"
+        end
+        Base64.decode64(auth_tag_b64)
+      end
+
+      def openssl_decryptor
+        @openssl_decryptor ||= begin
+          d = super
+          d.auth_tag = auth_tag
+          d.auth_data = ''
+          d
+        end
+      end
+
+    end
+
   end
 end
diff --git a/lib/chef/encrypted_data_bag_item/encryption_failure.rb b/lib/chef/encrypted_data_bag_item/encryption_failure.rb
new file mode 100644
index 0000000000..380e9bc1f7
--- /dev/null
+++ b/lib/chef/encrypted_data_bag_item/encryption_failure.rb
@@ -0,0 +1,22 @@
+#
+# Author:: Xabier de Zuazo (<xabier@onddo.com>)
+# Copyright:: Copyright (c) 2014 Onddo Labs, SL.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+class Chef::EncryptedDataBagItem
+  class EncryptionFailure < StandardError
+  end
+end
diff --git a/lib/chef/encrypted_data_bag_item/encryptor.rb b/lib/chef/encrypted_data_bag_item/encryptor.rb
index 9686e84b34..a3f3011c21 100644
--- a/lib/chef/encrypted_data_bag_item/encryptor.rb
+++ b/lib/chef/encrypted_data_bag_item/encryptor.rb
@@ -22,6 +22,7 @@ require 'openssl'
 require 'ffi_yajl'
 require 'chef/encrypted_data_bag_item'
 require 'chef/encrypted_data_bag_item/unsupported_encrypted_data_bag_item_format'
+require 'chef/encrypted_data_bag_item/encryption_failure'
 
 class Chef::EncryptedDataBagItem
 
@@ -40,9 +41,11 @@ class Chef::EncryptedDataBagItem
         Version1Encryptor.new(value, secret, iv)
       when 2
         Version2Encryptor.new(value, secret, iv)
+      when 3
+        Version3Encryptor.new(value, secret, iv)
       else
         raise UnsupportedEncryptedDataBagItemFormat,
-          "Invalid encrypted data bag format version `#{format_version}'. Supported versions are '1', '2'"
+          "Invalid encrypted data bag format version `#{format_version}'. Supported versions are '1', '2', '3'"
       end
     end
 
@@ -65,6 +68,11 @@ class Chef::EncryptedDataBagItem
         @iv = iv && Base64.decode64(iv)
       end
 
+      # Returns the used encryption algorithm
+      def algorithm
+        ALGORITHM
+      end
+
       # Returns a wrapped and encrypted version of +plaintext_data+ suitable for
       # using as the value in an encrypted data bag item.
       def for_encrypted_item
@@ -72,7 +80,7 @@ class Chef::EncryptedDataBagItem
           "encrypted_data" => encrypted_data,
           "iv" => Base64.encode64(iv),
           "version" => 1,
-          "cipher" => ALGORITHM
+          "cipher" => algorithm
         }
       end
 
@@ -88,11 +96,12 @@ class Chef::EncryptedDataBagItem
       # it for the specified iv and encryption key.
       def openssl_encryptor
         @openssl_encryptor ||= begin
-          encryptor = OpenSSL::Cipher::Cipher.new(ALGORITHM)
+          encryptor = OpenSSL::Cipher::Cipher.new(algorithm)
           encryptor.encrypt
+          # We must set key before iv: https://bugs.ruby-lang.org/issues/8221
+          encryptor.key = Digest::SHA256.digest(key)
           @iv ||= encryptor.random_iv
           encryptor.iv = @iv
-          encryptor.key = Digest::SHA256.digest(key)
           encryptor
         end
       end
@@ -125,7 +134,7 @@ class Chef::EncryptedDataBagItem
           "hmac" => hmac,
           "iv" => Base64.encode64(iv),
           "version" => 2,
-          "cipher" => ALGORITHM
+          "cipher" => algorithm
         }
       end
 
@@ -138,5 +147,62 @@ class Chef::EncryptedDataBagItem
         end
       end
     end
+
+    class Version3Encryptor < Version1Encryptor
+
+      def initialize(plaintext_data, key, iv=nil)
+        super
+        @auth_tag = nil
+      end
+
+      # Returns a wrapped and encrypted version of +plaintext_data+ suitable for
+      # using as the value in an encrypted data bag item.
+      def for_encrypted_item
+        {
+          "encrypted_data" => encrypted_data,
+          "iv" => Base64.encode64(iv),
+          "auth_tag" => Base64.encode64(auth_tag),
+          "version" => 3,
+          "cipher" => algorithm
+        }
+      end
+
+      # Returns the used encryption algorithm
+      def algorithm
+        AEAD_ALGORITHM
+      end
+
+      # Returns a wrapped and encrypted version of +plaintext_data+ suitable for
+      # Returns the auth_tag.
+      def auth_tag
+        # Generated auth_tag comes from OpenSSL::Cipher::Cipher#auth_tag
+        # This must be generated after the data is encrypted
+        if @auth_tag.nil?
+          raise EncryptionFailure, "Internal Error: GCM authentication tag read before encryption"
+        end
+        @auth_tag
+      end
+
+      # Generates (and memoizes) an OpenSSL::Cipher::Cipher object and configures
+      # it for the specified iv and encryption key using AEAD
+      def openssl_encryptor
+        @openssl_encryptor ||= begin
+          encryptor = super
+          encryptor.auth_data = ''
+          encryptor
+        end
+      end
+
+      # Encrypts, Base64 encodes +serialized_data+ and gets the authentication tag
+      def encrypted_data
+        @encrypted_data ||= begin
+          enc_data_b64 = super
+          @auth_tag = openssl_encryptor.auth_tag
+          enc_data_b64
+        end
+      end
+
+    end
+
   end
 end