class ActiveSupport::MessageEncryptor

Experimental RBS support (using type sampling data from the `type_fusion` project).

# sig/active_support/message_encryptor.rbs

class ActiveSupport::MessageEncryptor < ActiveSupport::Messages::Codec
  def initialize: (String secret, ?nil sign_secret, **Hash options) -> void
end

crypt.rotate old_secret, cipher: “aes-256-cbc”
the above should be combined into:
Though if both the secret and the cipher was changed at the same time,
crypt.rotate cipher: “aes-256-cbc” # Fallback to an old cipher instead of aes-256-gcm.
crypt.rotate old_secret # Fallback to an old secret instead of @secret.
generated with the old values will then work until the rotation is removed.
Then gradually rotate the old values out by adding them as fallbacks. Any message
crypt = ActiveSupport::MessageEncryptor.new(@secret, cipher: “aes-256-gcm”)
You’d give your encryptor the new defaults:
encryptor unless specified otherwise.
By default any rotated encryptors use the values of the primary
so decrypt_and_verify will also try the fallback.
back to a stack of encryptors. Call rotate to build and add an encryptor
MessageEncryptor also supports rotating out old configurations by falling
=== Rotating keys
Thereafter, verifying returns nil.
Then the messages can be verified and returned up to the expire time.
crypt.encrypt_and_sign(doowad, expires_at: Time.now.end_of_year)
crypt.encrypt_and_sign(parcel, expires_in: 1.month)
time with :expires_in or :expires_at.
return the original value. But messages can be set to expire at a given
By default messages last forever and verifying one year from now will still
=== Making messages expire
crypt.decrypt_and_verify(token) # => “the conversation is lively”
crypt.decrypt_and_verify(token, purpose: :scare_tactics) # => nil
token = crypt.encrypt_and_sign(“the conversation is lively”)
a specific purpose.
Likewise, if a message has no purpose it won’t be returned when verifying with
crypt.decrypt_and_verify(token) # => nil
crypt.decrypt_and_verify(token, purpose: :shipping) # => nil
crypt.decrypt_and_verify(token, purpose: :login) # => “this is the chair”
Then that same purpose must be passed when verifying to get the data back out:
token = crypt.encrypt_and_sign(“this is the chair”, purpose: :login)
confined to a specific :purpose.
By default any message can be used throughout your app. But they can also be
=== Confining messages to a specific purpose
crypt.decrypt_and_verify(‘not encrypted data’) # => ActiveSupport::MessageEncryptor::InvalidMessage
provided cannot be decrypted or verified.
ActiveSupport::MessageEncryptor::InvalidMessage exception if the data
The decrypt_and_verify method will raise an
crypt.decrypt_and_verify(encrypted_data) # => “my secret data”
encrypted_data = crypt.encrypt_and_sign(‘my secret data’) # => “NlFBTTMwOUV5UlA1QlNEN2xkY2d6eThYWWh…”
crypt = ActiveSupport::MessageEncryptor.new(key) # => #<ActiveSupport::MessageEncryptor …>
key = ActiveSupport::KeyGenerator.new(‘password’).generate_key(salt, len) # => “x89xE0x156xAC…”
salt = SecureRandom.random_bytes(len)
len = ActiveSupport::MessageEncryptor.key_len
where you don’t want users to be able to determine the value of the payload.
This can be used in situations similar to the MessageVerifier, but
to you.
The cipher text and initialization vector are base64 encoded and returned
somewhere you don’t trust.
MessageEncryptor is a simple way to encrypt values which get stored
= Active Support Message Encryptor

def self.key_len(cipher = default_cipher)

Given a cipher, returns the key length of the cipher to help generate the key of desired size

def self.key_len(cipher = default_cipher)
  OpenSSL::Cipher.new(cipher).key_len
end

def create_message(value, **options) # :nodoc:

:nodoc:

def create_message(value, **options) # :nodoc:
  sign(encrypt(serialize_with_metadata(value, **options)))
end

def decrypt(encrypted_message)

def decrypt(encrypted_message)
  cipher = new_cipher
  encrypted_data, iv, auth_tag = extract_parts(encrypted_message)
  # Currently the OpenSSL bindings do not raise an error if auth_tag is
  # truncated, which would allow an attacker to easily forge it. See
  # https://github.com/ruby/openssl/issues/63
  if aead_mode? && auth_tag.bytesize != AUTH_TAG_LENGTH
    throw :invalid_message_format, "truncated auth_tag"
  end
  cipher.decrypt
  cipher.key = @secret
  cipher.iv  = iv
  if aead_mode?
    cipher.auth_tag = auth_tag
    cipher.auth_data = ""
  end
  decrypted_data = cipher.update(encrypted_data)
  decrypted_data << cipher.final
rescue OpenSSLCipherError => error
  throw :invalid_message_format, error
end

def decrypt_and_verify(message, **options)

encryptor.decrypt_and_verify(message, purpose: "greeting") # => nil
encryptor.decrypt_and_verify(message) # => "bye"
message = encryptor.encrypt_and_sign("bye")

encryptor.decrypt_and_verify(message) # => nil
encryptor.decrypt_and_verify(message, purpose: "greeting") # => "hello"
message = encryptor.encrypt_and_sign("hello", purpose: "greeting")

match, +decrypt_and_verify+ will return +nil+.
The purpose that the message was generated with. If the purpose does not
[+:purpose+]

==== Options

avoid padding attacks. Reference: https://www.limited-entropy.com/padding-oracle-attacks/.
Decrypt and verify a message. We need to verify the message in order to

def decrypt_and_verify(message, **options)
  catch_and_raise :invalid_message_format, as: InvalidMessage do
    catch_and_raise :invalid_message_serialization, as: InvalidMessage do
      catch_and_ignore :invalid_message_content do
        read_message(message, **options)
      end
    end
  end
end

def default_cipher # :nodoc:

:nodoc:

def default_cipher # :nodoc:
  if use_authenticated_message_encryption
    "aes-256-gcm"
  else
    "aes-256-cbc"
  end
end

def encrypt(data)

def encrypt(data)
  cipher = new_cipher
  cipher.encrypt
  cipher.key = @secret
  # Rely on OpenSSL for the initialization vector
  iv = cipher.random_iv
  cipher.auth_data = "" if aead_mode?
  encrypted_data = cipher.update(data)
  encrypted_data << cipher.final
  parts = [encrypted_data, iv]
  parts << cipher.auth_tag(AUTH_TAG_LENGTH) if aead_mode?
  join_parts(parts)
end

def encrypt_and_sign(value, **options)

(See #decrypt_and_verify.)
specified when verifying the message; otherwise, verification will fail.
The purpose of the message. If specified, the same purpose must be
[+:purpose+]

encryptor.decrypt_and_verify(message) # => nil
# 24 hours later...
encryptor.decrypt_and_verify(message) # => "hello"
message = encryptor.encrypt_and_sign("hello", expires_in: 24.hours)

elapsed, verification of the message will fail.
The duration for which the message is valid. After this duration has
[+:expires_in+]

encryptor.decrypt_and_verify(message) # => nil
# 24 hours later...
encryptor.decrypt_and_verify(message) # => "hello"
message = encryptor.encrypt_and_sign("hello", expires_at: Time.now.tomorrow)

verification of the message will fail.
The datetime at which the message expires. After this datetime,
[+:expires_at+]

==== Options

padding attacks. Reference: https://www.limited-entropy.com/padding-oracle-attacks/.
Encrypt and sign a message. We need to sign the message in order to avoid

def encrypt_and_sign(value, **options)
  create_message(value, **options)
end

def extract_part(encrypted_message, rindex, length)

def extract_part(encrypted_message, rindex, length)
  index = rindex - length
  if encrypted_message[index - SEPARATOR.length, SEPARATOR.length] == SEPARATOR
    encrypted_message[index, length]
  else
    throw :invalid_message_format, "missing separator"
  end
end

def extract_parts(encrypted_message)

def extract_parts(encrypted_message)
  parts = []
  rindex = encrypted_message.length
  if aead_mode?
    parts << extract_part(encrypted_message, rindex, length_of_encoded_auth_tag)
    rindex -= SEPARATOR.length + length_of_encoded_auth_tag
  end
  parts << extract_part(encrypted_message, rindex, length_of_encoded_iv)
  rindex -= SEPARATOR.length + length_of_encoded_iv
  parts << encrypted_message[0, rindex]
  parts.reverse!.map! { |part| decode(part) }
end

def initialize(secret, sign_secret = nil, **options)

Experimental RBS support (using type sampling data from the `type_fusion` project).

def initialize: (String secret, ?nil sign_secret, **cipher | String | serializer | Module options) -> void

This signature was generated using 1 sample from 1 application.

+config.active_support.use_message_serializer_for_metadata+.
If you don't pass a truthy value, the default is set using

was the default in \Rails 7.0 and below.
message first, then wraps it in an envelope which is also serialized. This
Whether to use the legacy metadata serializer, which serializes the
[+:force_legacy_metadata_serializer+]

pass +true+.
Encoding with URL and Filename Safe Alphabet" in RFC 4648), you can
If you want to generate URL-safe strings (in compliance with "Base 64
which are not URL-safe. In other words, they can contain "+" and "/".
By default, MessageEncryptor generates RFC 4648 compliant strings
[+:url_safe+]

Otherwise, the default is +:marshal+.
When using \Rails, the default depends on +config.active_support.message_serializer+.

these require the +msgpack+ gem.
not supported by JSON, and may provide improved performance. However,
ActiveSupport::MessagePack, which can roundtrip some Ruby types that are
The +:message_pack+ and +:message_pack_allow_marshal+ serializers use

possible, choose a serializer that does not support +Marshal+.
attacks in cases where a message signing secret has been leaked. If
not. Beware that +Marshal+ is a potential vector for deserialization
serializers support deserializing using +Marshal+, but the others do
The +:marshal+, +:json_allow_marshal+, and +:message_pack_allow_marshal+

to migrate between serializers.
ActiveSupport::JSON, or ActiveSupport::MessagePack. This makes it easy
will serialize using +Marshal+, but can deserialize using +Marshal+,
multiple deserialization formats. For example, the +:marshal+ serializer
The preconfigured serializers include a fallback mechanism to support

+:json+, +:message_pack_allow_marshal+, +:message_pack+.
several preconfigured serializers: +:marshal+, +:json_allow_marshal+,
object that responds to +dump+ and +load+, or you can choose from
The serializer used to serialize message data. You can specify any
[+:serializer+]

'aes-256-gcm'.
Digest used for signing. Ignored when using an AEAD cipher like
[+:digest+]

Default is 'aes-256-gcm'.
Cipher to use. Can be any cipher returned by +OpenSSL::Cipher.ciphers+.
[+:cipher+]

==== Options

ActiveSupport::MessageEncryptor.new('secret', 'signature_secret')

data. Ignored when using an AEAD cipher like 'aes-256-gcm'.
MessageVerifier. This allows you to specify keys to encrypt and sign
The first additional parameter is used as the signature key for

derivation function.
key by using ActiveSupport::KeyGenerator or a similar key
bits. If you are using a user-entered secret, you can generate a suitable
the cipher key size. For the default 'aes-256-gcm' cipher, this is 256
Initialize a new MessageEncryptor. +secret+ must be at least as long as

def initialize(secret, sign_secret = nil, **options) super(**options) @secret = secret @cipher = options[:cipher] || self.class.default_cipher @aead_mode = new_cipher.authenticated? @verifier = if !@aead_mode MessageVerifier.new(sign_secret || secret, **options, serializer: NullSerializer) end end

def inspect # :nodoc:

:nodoc:

def inspect # :nodoc: "#<#{self.class.name}:#{'%#016x' % (object_id << 1)}>" end

def join_parts(parts)

def join_parts(parts) parts.map! { |part| encode(part) }.join(SEPARATOR) end

def length_after_encode(length_before_encode)

def length_after_encode(length_before_encode) if @url_safe (4 * length_before_encode / 3.0).ceil # length without padding else 4 * (length_before_encode / 3.0).ceil # length with padding end end

def length_of_encoded_auth_tag

def length_of_encoded_auth_tag @length_of_encoded_auth_tag ||= length_after_encode(AUTH_TAG_LENGTH) end

def length_of_encoded_iv

def length_of_encoded_iv @length_of_encoded_iv ||= length_after_encode(new_cipher.iv_len) end

def new_cipher

def new_cipher OpenSSL::Cipher.new(@cipher) end

def read_message(message, **options) # :nodoc:

:nodoc:

def read_message(message, **options) # :nodoc: deserialize_with_metadata(decrypt(verify(message)), **options) end

def sign(data)

def sign(data) @verifier ? @verifier.create_message(data) : data end

def verify(data)

def verify(data) @verifier ? @verifier.read_message(data) : data end

Namespace

ActiveSupport

Classes in this namespace

ActiveSupport::MessageEncryptor::InvalidMessage

Parent class

ActiveSupport::Messages::Codec

Class Methods

:: key_len

Instance Methods

# create_message

# decrypt

# decrypt_and_verify

# default_cipher

# encrypt

# encrypt_and_sign

# extract_part

# extract_parts

# initialize

# inspect

# join_parts

# length_after_encode

# length_of_encoded_auth_tag

# length_of_encoded_iv

# new_cipher

# read_message

# sign

# verify

Defined in

lib/active_support/message_encryptor.rb

class ActiveSupport::MessageEncryptor

Experimental RBS support (using type sampling data from the type_fusion project).

def self.key_len(cipher = default_cipher)

def create_message(value, **options) # :nodoc:

def decrypt(encrypted_message)

def decrypt_and_verify(message, **options)

def default_cipher # :nodoc:

def encrypt(data)

def encrypt_and_sign(value, **options)

def extract_part(encrypted_message, rindex, length)

def extract_parts(encrypted_message)

def initialize(secret, sign_secret = nil, **options)

Experimental RBS support (using type sampling data from the type_fusion project).

def inspect # :nodoc:

def join_parts(parts)

def length_after_encode(length_before_encode)

def length_of_encoded_auth_tag

def length_of_encoded_iv

def new_cipher

def read_message(message, **options) # :nodoc:

def sign(data)

def verify(data)

Namespace

Classes in this namespace

Parent class

Class Methods

Instance Methods

Defined in

Experimental RBS support (using type sampling data from the `type_fusion` project).

Experimental RBS support (using type sampling data from the `type_fusion` project).