keys_for (Net::SSH::KnownHosts)

    # File lib/net/ssh/known-hosts.rb, line 56
        def keys_for(host)
          keys = []
          hosts = Array(host)

          File.open(source) do |file|
            scanner = StringScanner.new("")
            file.each_line do |line|
              scanner.string = line

              scanner.skip(/\s*/)
              next if scanner.match?(/$|#/)

              hostlist = scanner.scan(/\S+/)
              next if (hostlist.split(/,/) & hosts).empty?

              scanner.skip(/\s*/)
              type = scanner.scan(/\S+/)
              scanner.skip(/\s*/)
              blob = scanner.rest.unpack("m*").first
              keys << Net::SSH::Transport::OSSL::Buffer.new(blob).read_key
            end
          end

          keys
        rescue SystemCallError
          return []
        end