# File lib/gpgr.rb, line 160
    def self.installed_public_keys
      keys = []
      email_regexp = /\<(.*@.*)\>/

      # Select the output to grep for, which is different depending on the version
      # of GPG installed. This is tested on 1.4 and 2.1.
      #
      if `#{Gpgr.command} --version | grep GnuPG`.include?('1.')
        grep_for = 'pub'
      else
        grep_for = 'uid'
      end

      `#{Gpgr.command} --list-public-keys --with-colons | grep #{grep_for}`.split("\n").each do |key| 
        keys << email_regexp.match(key)[1].upcase
      end

      keys.uniq
    end