class Net::SSH::KnownHosts

def known_host_hash?(hostlist, entries, scanner)
  if hostlist.size == 1 && hostlist.first =~ /\A\|1(\|.+){2}\z/
    chunks = hostlist.first.split(/\|/)
    salt = Base64.decode64(chunks[2])
    digest = OpenSSL::Digest.new('sha1')
    entries.each do |entry|
      hmac = OpenSSL::HMAC.digest(digest, salt, entry)
      return true if Base64.encode64(hmac).chomp == chunks[3]
    end
  end
  false
end