Add config options
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Jorge Manrubia
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@ -5,7 +5,7 @@ Active Record Encryption
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This guide covers encrypting your database information using Active Record.
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After reading this guide, you will know:
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After reading this guide you will know:
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* How to set up database encryption with Active Record.
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* How to migrate unencrypted data
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@ -15,7 +15,7 @@ After reading this guide, you will know:
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--------------------------------------------------------------------------------
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Active Record supports application-level encryption. It works by declaring which attributes should be encrypted and seamlessly encrypting and decrypting them when necessary. The encryption layer is placed between the database and the application. The application will access unencrypted data, but the database will store it encrypted.
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Active Record supports application-level encryption. To use by declaring which attributes should be encrypted and seamlessly encrypting and decrypting them when necessary. The encryption layer is placed between the database and the application. The application will access unencrypted data but the database will store it encrypted.
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## Basic usage
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@ -33,21 +33,21 @@ active_record.encryption:
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key_derivation_salt: xEY0dt6TZcAMg52K7O84wYzkjvbA62Hz
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```
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NOTE: These generated keys and salt are 32 bytes in length. If you generate these yourself, the minimum size you should use are 12 bytes for the master key (this will be used to derive the AES 32 bytes key) and 20 bytes for the salt.
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NOTE: These generated keys and salt are 32 bytes length. If you generate these yourself, the minimum lengths you should use are 12 bytes for the master key (this will be used to derive the AES 32 bytes key) and 20 bytes for the salt.
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### Declaration of encrypted attributes
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Encryptable attributes are defined at the model level. These are regular active record attributes backed by a column with the same name.
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Encryptable attributes attributes are defined the model level. These are regular active record attributes backed by a column with the same name.
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```ruby
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class Article < ApplicationRecord
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encrypts :title
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end
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````
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The library will transparently encrypt these attributes before saving them into the database, and will decrypt them when retrieving their values:
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```
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The library will transparently encrypt these attributes before saving them into the database and will decrypt them when retrieving their values:
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```ruby
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article = Article.create title: "Encrypt it all!"
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article.title # => "Encrypt it all"
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```
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@ -58,13 +58,13 @@ But, under the hood, the executed SQL would look like this:
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INSERT INTO `articles` (`title`) VALUES ('{\"p\":\"n7J0/ol+a7DRMeaE\",\"h\":{\"iv\":\"DXZMDWUKfp3bg/Yu\",\"at\":\"X1/YjMHbHD4talgF9dt61A==\"}}')
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```
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Encryption takes additional space in the column. You can estimate the worst-case overload in around 250 bytes when the built-in envelope encryption key provider is used. For medium and large text columns, this overload is negligible, but for `string` columns of 255 bytes, you should increase their limit accordingly (510 is recommended).
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Encryption takes additional space in the column. You can estimate the worst-case overload in around 250 bytes when the built-in envelope encryption key provider is used. For medium and large text columns this overload is negligible, but for `string` columns of 255 bytes, you should increase their limit accordingly (510 is recommended).
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NOTE: The reason for the additional space is that values are encoded in Base 64 and, also, that additional metadata is stored with the encrypted values.
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NOTE: The reason for the additional space is that values are encoded in Base 64 and, also, that additional metadata is stored with the encrypted values.
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### Deterministic and non-deterministic encryption
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By default, Active Record Encryption uses a non-deterministic approach to encryption. This means that encrypting the same content with the same password twice will result in different ciphertexts. This is good for security since it makes crypto-analysis of encrypted content much harder. But it makes querying the database impossible.
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By default, Active Record Encryption uses a non-deterministic approach to encryption. This means that encrypting the same content with the same password twice will result in different ciphertexts. This is good for security, since it makes crypto-analysis of encrypted content much harder. But it makes querying the database impossible.
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You can use the `:deterministic` option to generate initialization vectors in a deterministic way, effectively enabling querying encrypted data.
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@ -76,7 +76,7 @@ end
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Author.find_by_email("some@email.com") # You can query the model normally
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```
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NOTE: In non-deterministic mode, encryption is done using AES-GCM with a 256-bits key and a random initialization vector. In deterministic mode, it uses AES-GCM too, but the initialization vector is generated as an HMAC-SHA-256 digest of the key and contents to encrypt.
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NOTE: In non-deterministic mode, encryption is done using AES-GCM with a 256-bits key and a random initialization vector. In deterministic mode, it uses AES-GCM too but the initialization vector is generated as a HMAC-SHA-256 digest of the key and contents to encrypt.
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## Features
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@ -84,7 +84,7 @@ NOTE: In non-deterministic mode, encryption is done using AES-GCM with a 256-bit
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You can encrypt action text attributes by passing `encrypted: true` in their declaration.
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```ruby
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```
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class Message < ApplicationRecord
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has_rich_text :content, encrypted: true
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end
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@ -106,44 +106,35 @@ When enabled, all the encryptable attributes will be encrypted according to the
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`active_record.encryption` will serialize values using the underlying type before encrypting them, but *they must be serializable as strings*, as that will be the value that the library will encrypt. Structured types like `serialized` are supported out of the box.
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If you need to support a custom type, the recommended way is using a [serialized attribute](https://api.rubyonrails.org/classes/ActiveRecord/AttributeMethods/Serialization/ClassMethods.html). The declaration of the serialized attribute should go **before** the encryption declaration:
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If you need to support a custom type, the recommended way is using a [serialized attribute](https://api.rubyonrails.org/classes/ActiveRecord/AttributeMethods/Serialization/ClassMethods.html). The declaration of the serialized attribute should go **before** the encryption declaration:
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```ruby
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# GOOD
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class Article < ApplicationRecord
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serialize :title, Title
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encrypts :title
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serialize :title, Title
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encrypts :title
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end
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# WRONG
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class Article < ApplicationRecord
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encrypts :title
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serialize :title, Title
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encrypts :title
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serialize :title, Title
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end
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```
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### Support for unencrypted data
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To ease migrations of unencrypted data, the library includes the option `config.active_record.encryption.support_unencrypted_data`. When set to `true`:
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* Trying to read encrypted attributes that are not encrypted will work without raising any error
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* Queries with deterministically-encrypted attributes will include the "clear text" version of them to support finding both encrypted and unencrypted content.
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**This option is meant to be used in transition periods** while clear data and encrypted data need to coexist. Its value is `false` by default, which is the recommended goal for any application: errors will be raised when working with unencrypted data.
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### Ignoring case
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You might need to ignore case when querying deterministically encrypted data. There are two options that can help you here.
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You can use the `:downcase` when declaring the encrypted attribute. This will downcase the value before being encrypted.
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You can use the option `:downcase` when declaring the encrypted attribute. This will make that content is downcased before being encrypted.
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```ruby
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class Person
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encrypts :email_address, deterministic: true, downcase: true
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encrypts :email_address, deterministic: true, downcase: true
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end
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```
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When using `:downcase` the original case is lost. There might be cases where you need to preserve the original case when reading the value, but you need to ignore the case when querying. For those cases you can use the option `:ignore_case`, which requires you to add a new column named `original_<column_name>` to store the content with the case unchanged:
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When using `:downcase` the original case is lost. There might be cases where you need to preserve the original case when reading the value, but you need to ignore the case when querying. For those cases you can use the option `:ignore_case` which requires you to add a new column named `original_<column_name>` to store the content with the case unchanged:
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```ruby
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class Label
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@ -151,9 +142,18 @@ class Label
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end
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```
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### Support for unencrypted data
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To ease migrations of unencrypted data, the library includes the option `config.active_record.encryption.support_unencrypted_data`. When set to `true`:
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* Trying to read encrypted attributes that are not encrypted will work normally, without raising any error
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* Queries with deterministically-encrypted attributes will include the "clear text" version of them, to support finding both encrypted and unencrypted content. You need to set `config.active_record.encryption.extend_queries = true` to enable this.
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**This options is meant to be used in transition periods** while clear data and encrypted data need to coexist. Their value is `false` by default, which is the recommended goal for any application: errors will be raised when working with unencrypted data.
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### Support for previous encrypting schemes
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Changing encryption properties of attributes can break existing data. For example, imagine you wan to make a "deterministic" attribute ""non-deterministic. If you just change the model's declaration, reading existing ciphertexts will fail because they are different now.
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Changing encryption properties of attributes can break existing data. For example, imagine you wan to make a "deterministic" attribute "not deterministic". If you just change the declaration in the model, reading existing ciphertexts will fail because they are different now.
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To support these situations, you can use `:previous` to declare previous encryption schemes:
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@ -165,7 +165,7 @@ end
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This declaration has 2 effects:
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* When reading encrypted data, Active Record Encryption will try previous encryption schemes if the current scheme doesn't work.
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* When querying deterministic data, it will add ciphertexts using previous schemes to the queries, so it works seamlessly with data encrypted with different schemes.
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* When querying deterministic data, it will add ciphertexts using previous schemes to the queries so that queries work seamlessly with data encrypted with different scheme. You need to set `config.active_record.encryption.extend_queries = true` to enable this.
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### Filtering params named as encrypted columns
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@ -179,13 +179,13 @@ In case you want exclude specific columns from this automatic filtering, add the
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## Key management
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Key management strategies are implemented by key providers. You can configure key providers globally or on a per attribute basis.
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Key management strategies are implemented by key providers. You can configure key providers globally or on a per-attribute basis.
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### Built-in key providers
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#### DerivedSecretKeyProvider
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A key provider that will serve keys derived from the provided passwords using PBKDF2.
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A key provider that will serve keys derived from the provided passwords using PBKDF2.
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```ruby
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config.active_record.encryption.key_provider = ActiveRecord::Encryption::DerivedSecretKeyProvider.new(["some passwords", "to derive keys from. ", "These should be in", "credentials"])
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@ -265,11 +265,11 @@ The key will be used internally to derive the key used to encrypt and decrypt th
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- All the keys will be tried when decrypting content, until one works.
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```yml
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active_record_encryption:
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master_key:
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- bc17e7b413fd4720716a7633027f8cc4 # Active, encrypts new content
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- a1cc4d7b9f420e40a337b9e68c5ecec6 # Previous keys can still decrypt existing content
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key_derivation_salt: a3226b97b3b2f8372d1fc6d497a0c0d3
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active_record.encryption:
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master_key:
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- bc17e7b413fd4720716a7633027f8cc4 # Active, encrypts new content
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- a1cc4d7b9f420e40a337b9e68c5ecec6 # Previous keys can still decrypt existing content
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key_derivation_salt: a3226b97b3b2f8372d1fc6d497a0c0d3
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```
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This enabled workflows where you keep a short list of keys, by adding new keys, re-encrypting content and deleting old keys.
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@ -277,23 +277,23 @@ This enabled workflows where you keep a short list of keys, by adding new keys,
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This works consistently across the built-in key providers. Also, when using a deterministic encryption strategy, you can set a list of keys in `active_record.encryption.deterministic_key`.
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```yaml
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active_record_encryption:
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active_record.encryption:
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deterministic_key:
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- dd9e4ffef6eced8317667d70df7c75eb # Active, encrypts new content
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- 6940371df37f040e0e8a12948bb31cda # Previous keys can still decrypt existing content
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- dd9e4ffef6eced8317667d70df7c75eb # Active, encrypts new content
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- 6940371df37f040e0e8a12948bb31cda # Previous keys can still decrypt existing content
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```
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NOTE: Active Record Encryption doesn't provide automatic management of key rotation processes yet. All the pieces are there, but this hasn't been implemented yet.
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NOTE: Active Record Encryption doesn't provide automatic management of key rotation processes yet. All the pieces are there, but this hasn't been implemented yet.
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### Storing key references
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There is a setting `active_record.encryption.store_key_references` you can use to make `active_record.encryption` store a reference to the encryption key in the encrypted message itself.
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There is a setting `active_record.encryption.store_key_references` you can use to make `active_record.encryption` store a reference to the encryption key in the encrypted message itself.
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```ruby
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config.active_record.encryption.store_key_references = true
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```
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This makes for more performant decryption since, instead of trying lists of keys, the system can now locate keys directly. The price to pay is storage: encrypted data will be a bit bigger in size.
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This makes for a more performant decryption since, instead of trying lists of keys, the system can now locate keys directly. The price to pay is storage: encrypted data will be a bit bigger in size.
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## API
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@ -326,7 +326,7 @@ An encryption context defines the encryption components that are used in a given
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```ruby
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ActiveRecord::Encryption.with_encryption_context(encryptor: ActiveRecord::Encryption::NullEncryptor.new) do
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...
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...
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end
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```
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@ -341,7 +341,7 @@ ActiveRecord::Encryption.without_encryption do
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...
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end
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```
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This means that reading the encrypted text will return the ciphertext, and saved content will be stored unencrypted.
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This means that reading encrypted text will return the ciphertext and saved content will be stored unencrypted.
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#### Protect encrypted data
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@ -349,16 +349,36 @@ You can run code without encryption but preventing overwriting encrypted content
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```ruby
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ActiveRecord::Encryption.protecting_encrypted_data do
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...
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...
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end
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```
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This can be handy if you want to protect encrypted data while still letting someone run arbitrary code against it (e.g: in a Rails console).
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## Configuration
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### Configuration options reference
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### Configuration options
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### Advanced configuration
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You can configure Active Record Encryption options by setting them in your `application.rb` for setting them across environments (most common scenario) or in a specific environment config file `config/environments/<env name>.rb` if you want to set them on a per-environment basis.
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NOTE: It's important to use safe serializers that can't deserialize arbitrary objects. A common supported scenario is encrypting existing unencrypted data. An attacker can leverage this to enter a tampered payload before encryption takes place and perform RCE attacks. This means custom serializers should avoid `Marshal`, `YAML.load` (use `YAML.safe_load` instead) or `JSON.load` (use `JSON.parse` instead).
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All the config options are namespaced in `active_record.encryption.config`. For example:
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```ruby
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config.active_record.encryption.key_provider = ActiveRecord::Encryption::EnvelopeEncryptionKeyProvider.new
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config.active_record.encryption.store_key_references = true
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config.active_record.encryption.extend_queries = true
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```
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The available config options are:
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| Key | Value |
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| ------------------------------------------------------------ | ------------------------------------------------------------ |
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| `support_unencrypted_data` | When true, unencrypted data can be read normally. When false, it will raise. Default: false. |
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| `extend_queries` | When true, queries referencing deterministically encrypted attributes will be modified to include additional values if needed. Those additional values will be the clean version of the value, when `support_unencrypted_data` is true) and values encrypted with previous encryption schemes if any (as provided with the `previous:` option). Default: false (experimental). |
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| `encrypt_fixtures` | When true, encryptable attributes in fixtures will be automatically encrypted when those are loaded. Default: false. |
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| `store_key_references` | When true, a reference to the encryption key is stored in the headers of the encrypted message. This makes for a faster decryption when multiple keys are in use. Default: false. |
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| `add_to_filter_parameters` | When true, encrypted attribute names are added automatically to the [list of filtered params](https://guides.rubyonrails.org/configuring.html#rails-general-configuration) that won't be shown in logs. Default: true. |
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| `excluded_from_filter_parameters` | You can configure a list of params that won't be filtered out when `add_to_filter_parameters` is true. Default: []. |
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| `validate_column_size` | Adds a validation based on the column size. This is recommended to prevent storing huge values using highly compressible payloads. Default: true. |
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| `master_key` | The key or lists of keys that is used to derive root data-encryption keys. They way they are used depends on the key provider configured. It's preferred to configure it via a credential `active_record_encryption.master_key`. |
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| `deterministic_key` | The key or list of keys used for deterministic encryption. It's preferred to configure it via a credential `active_record_encryption.deterministic_key`. |
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| `key_derivation_salt` | The salt used when deriving keys. It's preferred to configure it via a credential `active_record_encryption.key_derivation_salt`. |
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