A Better Key Schedule for DES-like Ciphers
Uri Blumenthal, Steven M. Bellovin · 1996
Several DES-like ciphers aren't utilizing their full potential strength, because of the short key and linear or otherwise easily tractable algorithms they use to generate their key schedules. Using DES as example, we show a way to generate round subkeys to increase the cipher strength substantially by making relations between the round subkeys practically intractable.