ad20d9e7ec
The documentation on ActiveSupport::MessageVerifier used the “sensitive data” string as an example; that wording might induce the developer to think we’re dealing with encryption, while the payload is actually only Base64 encoded and is not protected at all. We also improve the documentation on ActiveRecord::SignedId, which uses MessageVerifier and thereby will also expose the ID as encoded cleartext, making explicit that it’s not encryption, only signing. Lastly, we refer the developer to MessageEncryptor if the payload needs to be encrypted.
369 lines
15 KiB
Ruby
369 lines
15 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
require "openssl"
|
|
require "base64"
|
|
require "active_support/core_ext/object/blank"
|
|
require "active_support/security_utils"
|
|
require "active_support/messages/codec"
|
|
require "active_support/messages/rotator"
|
|
|
|
module ActiveSupport
|
|
# = Active Support Message Verifier
|
|
#
|
|
# +MessageVerifier+ makes it easy to generate and verify messages which are
|
|
# signed to prevent tampering.
|
|
#
|
|
# In a \Rails application, you can use +Rails.application.message_verifier+
|
|
# to manage unique instances of verifiers for each use case.
|
|
# {Learn more}[link:classes/Rails/Application.html#method-i-message_verifier].
|
|
#
|
|
# This is useful for cases like remember-me tokens and auto-unsubscribe links
|
|
# where the session store isn't suitable or available.
|
|
#
|
|
# First, generate a signed message:
|
|
# cookies[:remember_me] = Rails.application.message_verifier(:remember_me).generate([@user.id, 2.weeks.from_now])
|
|
#
|
|
# Later verify that message:
|
|
#
|
|
# id, time = Rails.application.message_verifier(:remember_me).verify(cookies[:remember_me])
|
|
# if time.future?
|
|
# self.current_user = User.find(id)
|
|
# end
|
|
#
|
|
# === Signing is not encryption
|
|
#
|
|
# The signed messages are not encrypted. The payload is merely encoded (Base64 by default) and can be decoded by
|
|
# anyone. The signature is just assuring that the message wasn't tampered with. For example:
|
|
#
|
|
# message = Rails.application.message_verifier('my_purpose').generate('never put secrets here')
|
|
# # => "BAhJIhtuZXZlciBwdXQgc2VjcmV0cyBoZXJlBjoGRVQ=--a0c1c0827919da5e949e989c971249355735e140"
|
|
# Base64.decode64(message.split("--").first) # no key needed
|
|
# # => 'never put secrets here'
|
|
#
|
|
# If you also need to encrypt the contents, you must use ActiveSupport::MessageEncryptor instead.
|
|
#
|
|
# === Confine messages to a specific purpose
|
|
#
|
|
# It's not recommended to use the same verifier for different purposes in your application.
|
|
# Doing so could allow a malicious actor to re-use a signed message to perform an unauthorized
|
|
# action.
|
|
# You can reduce this risk by confining signed messages to a specific +:purpose+.
|
|
#
|
|
# token = @verifier.generate("signed message", purpose: :login)
|
|
#
|
|
# Then that same purpose must be passed when verifying to get the data back out:
|
|
#
|
|
# @verifier.verified(token, purpose: :login) # => "signed message"
|
|
# @verifier.verified(token, purpose: :shipping) # => nil
|
|
# @verifier.verified(token) # => nil
|
|
#
|
|
# @verifier.verify(token, purpose: :login) # => "signed message"
|
|
# @verifier.verify(token, purpose: :shipping) # => raises ActiveSupport::MessageVerifier::InvalidSignature
|
|
# @verifier.verify(token) # => raises ActiveSupport::MessageVerifier::InvalidSignature
|
|
#
|
|
# Likewise, if a message has no purpose it won't be returned when verifying with
|
|
# a specific purpose.
|
|
#
|
|
# token = @verifier.generate("signed message")
|
|
# @verifier.verified(token, purpose: :redirect) # => nil
|
|
# @verifier.verified(token) # => "signed message"
|
|
#
|
|
# @verifier.verify(token, purpose: :redirect) # => raises ActiveSupport::MessageVerifier::InvalidSignature
|
|
# @verifier.verify(token) # => "signed message"
|
|
#
|
|
# === Expiring messages
|
|
#
|
|
# By default messages last forever and verifying one year from now will still
|
|
# return the original value. But messages can be set to expire at a given
|
|
# time with +:expires_in+ or +:expires_at+.
|
|
#
|
|
# @verifier.generate("signed message", expires_in: 1.month)
|
|
# @verifier.generate("signed message", expires_at: Time.now.end_of_year)
|
|
#
|
|
# Messages can then be verified and returned until expiry.
|
|
# Thereafter, the +verified+ method returns +nil+ while +verify+ raises
|
|
# +ActiveSupport::MessageVerifier::InvalidSignature+.
|
|
#
|
|
# === Rotating keys
|
|
#
|
|
# MessageVerifier also supports rotating out old configurations by falling
|
|
# back to a stack of verifiers. Call +rotate+ to build and add a verifier so
|
|
# either +verified+ or +verify+ will also try verifying with the fallback.
|
|
#
|
|
# By default any rotated verifiers use the values of the primary
|
|
# verifier unless specified otherwise.
|
|
#
|
|
# You'd give your verifier the new defaults:
|
|
#
|
|
# verifier = ActiveSupport::MessageVerifier.new(@secret, digest: "SHA512", serializer: JSON)
|
|
#
|
|
# Then gradually rotate the old values out by adding them as fallbacks. Any message
|
|
# generated with the old values will then work until the rotation is removed.
|
|
#
|
|
# verifier.rotate(old_secret) # Fallback to an old secret instead of @secret.
|
|
# verifier.rotate(digest: "SHA256") # Fallback to an old digest instead of SHA512.
|
|
# verifier.rotate(serializer: Marshal) # Fallback to an old serializer instead of JSON.
|
|
#
|
|
# Though the above would most likely be combined into one rotation:
|
|
#
|
|
# verifier.rotate(old_secret, digest: "SHA256", serializer: Marshal)
|
|
class MessageVerifier < Messages::Codec
|
|
prepend Messages::Rotator
|
|
|
|
class InvalidSignature < StandardError; end
|
|
|
|
SEPARATOR = "--" # :nodoc:
|
|
SEPARATOR_LENGTH = SEPARATOR.length # :nodoc:
|
|
|
|
# Initialize a new MessageVerifier with a secret for the signature.
|
|
#
|
|
# ==== Options
|
|
#
|
|
# [+:digest+]
|
|
# Digest used for signing. The default is <tt>"SHA1"</tt>. See
|
|
# +OpenSSL::Digest+ for alternatives.
|
|
#
|
|
# [+:serializer+]
|
|
# The serializer used to serialize message data. You can specify any
|
|
# object that responds to +dump+ and +load+, or you can choose from
|
|
# several preconfigured serializers: +:marshal+, +:json_allow_marshal+,
|
|
# +:json+, +:message_pack_allow_marshal+, +:message_pack+.
|
|
#
|
|
# The preconfigured serializers include a fallback mechanism to support
|
|
# multiple deserialization formats. For example, the +:marshal+ serializer
|
|
# will serialize using +Marshal+, but can deserialize using +Marshal+,
|
|
# ActiveSupport::JSON, or ActiveSupport::MessagePack. This makes it easy
|
|
# to migrate between serializers.
|
|
#
|
|
# The +:marshal+, +:json_allow_marshal+, and +:message_pack_allow_marshal+
|
|
# serializers support deserializing using +Marshal+, but the others do
|
|
# not. Beware that +Marshal+ is a potential vector for deserialization
|
|
# attacks in cases where a message signing secret has been leaked. <em>If
|
|
# possible, choose a serializer that does not support +Marshal+.</em>
|
|
#
|
|
# The +:message_pack+ and +:message_pack_allow_marshal+ serializers use
|
|
# ActiveSupport::MessagePack, which can roundtrip some Ruby types that are
|
|
# not supported by JSON, and may provide improved performance. However,
|
|
# these require the +msgpack+ gem.
|
|
#
|
|
# When using \Rails, the default depends on +config.active_support.message_serializer+.
|
|
# Otherwise, the default is +:marshal+.
|
|
#
|
|
# [+:url_safe+]
|
|
# By default, MessageVerifier generates RFC 4648 compliant strings which are
|
|
# not URL-safe. In other words, they can contain "+" and "/". If you want to
|
|
# generate URL-safe strings (in compliance with "Base 64 Encoding with URL
|
|
# and Filename Safe Alphabet" in RFC 4648), you can pass +true+.
|
|
#
|
|
# [+:force_legacy_metadata_serializer+]
|
|
# Whether to use the legacy metadata serializer, which serializes the
|
|
# message first, then wraps it in an envelope which is also serialized. This
|
|
# was the default in \Rails 7.0 and below.
|
|
#
|
|
# If you don't pass a truthy value, the default is set using
|
|
# +config.active_support.use_message_serializer_for_metadata+.
|
|
def initialize(secret, **options)
|
|
raise ArgumentError, "Secret should not be nil." unless secret
|
|
super(**options)
|
|
@secret = secret
|
|
@digest = options[:digest]&.to_s || "SHA1"
|
|
end
|
|
|
|
# Checks if a signed message could have been generated by signing an object
|
|
# with the +MessageVerifier+'s secret.
|
|
#
|
|
# verifier = ActiveSupport::MessageVerifier.new("secret")
|
|
# signed_message = verifier.generate("signed message")
|
|
# verifier.valid_message?(signed_message) # => true
|
|
#
|
|
# tampered_message = signed_message.chop # editing the message invalidates the signature
|
|
# verifier.valid_message?(tampered_message) # => false
|
|
def valid_message?(message)
|
|
!!catch_and_ignore(:invalid_message_format) { extract_encoded(message) }
|
|
end
|
|
|
|
# Decodes the signed message using the +MessageVerifier+'s secret.
|
|
#
|
|
# verifier = ActiveSupport::MessageVerifier.new("secret")
|
|
#
|
|
# signed_message = verifier.generate("signed message")
|
|
# verifier.verified(signed_message) # => "signed message"
|
|
#
|
|
# Returns +nil+ if the message was not signed with the same secret.
|
|
#
|
|
# other_verifier = ActiveSupport::MessageVerifier.new("different_secret")
|
|
# other_verifier.verified(signed_message) # => nil
|
|
#
|
|
# Returns +nil+ if the message is not Base64-encoded.
|
|
#
|
|
# invalid_message = "f--46a0120593880c733a53b6dad75b42ddc1c8996d"
|
|
# verifier.verified(invalid_message) # => nil
|
|
#
|
|
# Raises any error raised while decoding the signed message.
|
|
#
|
|
# incompatible_message = "test--dad7b06c94abba8d46a15fafaef56c327665d5ff"
|
|
# verifier.verified(incompatible_message) # => TypeError: incompatible marshal file format
|
|
#
|
|
# ==== Options
|
|
#
|
|
# [+:purpose+]
|
|
# The purpose that the message was generated with. If the purpose does not
|
|
# match, +verified+ will return +nil+.
|
|
#
|
|
# message = verifier.generate("hello", purpose: "greeting")
|
|
# verifier.verified(message, purpose: "greeting") # => "hello"
|
|
# verifier.verified(message, purpose: "chatting") # => nil
|
|
# verifier.verified(message) # => nil
|
|
#
|
|
# message = verifier.generate("bye")
|
|
# verifier.verified(message) # => "bye"
|
|
# verifier.verified(message, purpose: "greeting") # => nil
|
|
#
|
|
def verified(message, **options)
|
|
catch_and_ignore :invalid_message_format do
|
|
catch_and_raise :invalid_message_serialization do
|
|
catch_and_ignore :invalid_message_content do
|
|
read_message(message, **options)
|
|
end
|
|
end
|
|
end
|
|
end
|
|
|
|
# Decodes the signed message using the +MessageVerifier+'s secret.
|
|
#
|
|
# verifier = ActiveSupport::MessageVerifier.new("secret")
|
|
# signed_message = verifier.generate("signed message")
|
|
#
|
|
# verifier.verify(signed_message) # => "signed message"
|
|
#
|
|
# Raises +InvalidSignature+ if the message was not signed with the same
|
|
# secret or was not Base64-encoded.
|
|
#
|
|
# other_verifier = ActiveSupport::MessageVerifier.new("different_secret")
|
|
# other_verifier.verify(signed_message) # => ActiveSupport::MessageVerifier::InvalidSignature
|
|
#
|
|
# ==== Options
|
|
#
|
|
# [+:purpose+]
|
|
# The purpose that the message was generated with. If the purpose does not
|
|
# match, +verify+ will raise ActiveSupport::MessageVerifier::InvalidSignature.
|
|
#
|
|
# message = verifier.generate("hello", purpose: "greeting")
|
|
# verifier.verify(message, purpose: "greeting") # => "hello"
|
|
# verifier.verify(message, purpose: "chatting") # => raises InvalidSignature
|
|
# verifier.verify(message) # => raises InvalidSignature
|
|
#
|
|
# message = verifier.generate("bye")
|
|
# verifier.verify(message) # => "bye"
|
|
# verifier.verify(message, purpose: "greeting") # => raises InvalidSignature
|
|
#
|
|
def verify(message, **options)
|
|
catch_and_raise :invalid_message_format, as: InvalidSignature do
|
|
catch_and_raise :invalid_message_serialization do
|
|
catch_and_raise :invalid_message_content, as: InvalidSignature do
|
|
read_message(message, **options)
|
|
end
|
|
end
|
|
end
|
|
end
|
|
|
|
# Generates a signed message for the provided value.
|
|
#
|
|
# The message is signed with the +MessageVerifier+'s secret.
|
|
# Returns Base64-encoded message joined with the generated signature.
|
|
#
|
|
# verifier = ActiveSupport::MessageVerifier.new("secret")
|
|
# verifier.generate("signed message") # => "BAhJIhNzaWduZWQgbWVzc2FnZQY6BkVU--f67d5f27c3ee0b8483cebf2103757455e947493b"
|
|
#
|
|
# ==== Options
|
|
#
|
|
# [+:expires_at+]
|
|
# The datetime at which the message expires. After this datetime,
|
|
# verification of the message will fail.
|
|
#
|
|
# message = verifier.generate("hello", expires_at: Time.now.tomorrow)
|
|
# verifier.verified(message) # => "hello"
|
|
# # 24 hours later...
|
|
# verifier.verified(message) # => nil
|
|
# verifier.verify(message) # => raises ActiveSupport::MessageVerifier::InvalidSignature
|
|
#
|
|
# [+:expires_in+]
|
|
# The duration for which the message is valid. After this duration has
|
|
# elapsed, verification of the message will fail.
|
|
#
|
|
# message = verifier.generate("hello", expires_in: 24.hours)
|
|
# verifier.verified(message) # => "hello"
|
|
# # 24 hours later...
|
|
# verifier.verified(message) # => nil
|
|
# verifier.verify(message) # => raises ActiveSupport::MessageVerifier::InvalidSignature
|
|
#
|
|
# [+:purpose+]
|
|
# The purpose of the message. If specified, the same purpose must be
|
|
# specified when verifying the message; otherwise, verification will fail.
|
|
# (See #verified and #verify.)
|
|
def generate(value, **options)
|
|
create_message(value, **options)
|
|
end
|
|
|
|
def create_message(value, **options) # :nodoc:
|
|
sign_encoded(encode(serialize_with_metadata(value, **options)))
|
|
end
|
|
|
|
def read_message(message, **options) # :nodoc:
|
|
deserialize_with_metadata(decode(extract_encoded(message)), **options)
|
|
end
|
|
|
|
def inspect # :nodoc:
|
|
"#<#{self.class.name}:#{'%#016x' % (object_id << 1)}>"
|
|
end
|
|
|
|
private
|
|
def sign_encoded(encoded)
|
|
digest = generate_digest(encoded)
|
|
encoded << SEPARATOR << digest
|
|
end
|
|
|
|
def extract_encoded(signed)
|
|
if signed.nil? || !signed.valid_encoding?
|
|
throw :invalid_message_format, "invalid message string"
|
|
end
|
|
|
|
if separator_index = separator_index_for(signed)
|
|
encoded = signed[0, separator_index]
|
|
digest = signed[separator_index + SEPARATOR_LENGTH, digest_length_in_hex]
|
|
end
|
|
|
|
unless digest_matches_data?(digest, encoded)
|
|
throw :invalid_message_format, "mismatched digest"
|
|
end
|
|
|
|
encoded
|
|
end
|
|
|
|
def generate_digest(data)
|
|
OpenSSL::HMAC.hexdigest(@digest, @secret, data)
|
|
end
|
|
|
|
def digest_length_in_hex
|
|
# In hexadecimal (AKA base16) it takes 4 bits to represent a character,
|
|
# hence we multiply the digest's length (in bytes) by 8 to get it in
|
|
# bits and divide by 4 to get its number of characters it hex. Well, 8
|
|
# divided by 4 is 2.
|
|
@digest_length_in_hex ||= OpenSSL::Digest.new(@digest).digest_length * 2
|
|
end
|
|
|
|
def separator_at?(signed_message, index)
|
|
signed_message[index, SEPARATOR_LENGTH] == SEPARATOR
|
|
end
|
|
|
|
def separator_index_for(signed_message)
|
|
index = signed_message.length - digest_length_in_hex - SEPARATOR_LENGTH
|
|
index unless index.negative? || !separator_at?(signed_message, index)
|
|
end
|
|
|
|
def digest_matches_data?(digest, data)
|
|
data.present? && digest.present? && ActiveSupport::SecurityUtils.secure_compare(digest, generate_digest(data))
|
|
end
|
|
end
|
|
end
|