# File lib/mcollective/ssl.rb, line 195
    def self.base64_decode(string)
      # The Base 64 character set is A-Z a-z 0-9 + / =
      # Also allow for whitespace, but raise if we get anything else
      if string !~ /^[A-Za-z0-9+\/=\s]+$/
        raise ArgumentError, 'invalid base64'
      end
      Base64.decode64(string)
    end