Use OpenSSL::Digest.const(...).new instead of OpenSSL::Digest::Digest.new(...)

activesupport/lib/active_support/message_verifier.rb

@@ -53,7 +53,7 @@ def secure_compare(a, b)
 
       def generate_digest(data)
         require 'openssl' unless defined?(OpenSSL)
-        OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new(@digest), @secret, data)
+        OpenSSL::HMAC.hexdigest(OpenSSL::Digest.const_get(@digest).new, @secret, data)
       end
   end
 end