MessageVerifier
makes it easy to generate and verify messages
which are signed to prevent tampering.
This is useful for cases like remember-me tokens and auto-unsubscribe links where the session store isn't suitable or available.
Remember Me:
cookies[:remember_me] = @verifier.generate([@user.id, 2.weeks.from_now])
In the authentication filter:
id, time = @verifier.verify(cookies[:remember_me]) if time < Time.now self.current_user = User.find(id) end
By default it uses Marshal to serialize the message. If you want to use another serialization method, you can set the serializer in the options hash upon initialization:
@verifier = ActiveSupport::MessageVerifier.new('s3Krit', serializer: YAML)
# File lib/active_support/message_verifier.rb, line 30 def initialize(secret, options = {}) raise ArgumentError, 'Secret should not be nil.' unless secret @secret = secret @digest = options[:digest] || 'SHA1' @serializer = options[:serializer] || Marshal end
# File lib/active_support/message_verifier.rb, line 53 def generate(value) data = encode(@serializer.dump(value)) "#{data}--#{generate_digest(data)}" end
# File lib/active_support/message_verifier.rb, line 37 def verify(signed_message) raise InvalidSignature if signed_message.nil? || !signed_message.valid_encoding? || signed_message.blank? data, digest = signed_message.split("--") if data.present? && digest.present? && ActiveSupport::SecurityUtils.secure_compare(digest, generate_digest(data)) begin @serializer.load(decode(data)) rescue ArgumentError => argument_error raise InvalidSignature if argument_error.message =~ %r{invalid base64} raise end else raise InvalidSignature end end
# File lib/active_support/message_verifier.rb, line 63 def decode(data) ::Base64.strict_decode64(data) end
# File lib/active_support/message_verifier.rb, line 59 def encode(data) ::Base64.strict_encode64(data) end
# File lib/active_support/message_verifier.rb, line 67 def generate_digest(data) require 'openssl' unless defined?(OpenSSL) OpenSSL::HMAC.hexdigest(OpenSSL::Digest.const_get(@digest).new, @secret, data) end