Clean room implementation of MD5, for use under fips-140 usage.
There are incendents where we need a md5 hash that isnt related to
communications, such as web server etags.

see test/test.rb for example usage

to patch for rails
require 'openssl'
if OpenSSL.fips_mode
  require 'digest/md5'
  require 'md5fips'
  class Digest::MD5
    class << self
      Digest::MD5.public_methods.each do |method|
        define_method method do |*args, &block|
          Digest::MD5Fips.new.send(method, *args, &block)
        end
      end
    end
  end
end
This will get around using MD5 for cache keys not crypto functions for fips.