摘要：We look at various ways of enhancing the strength of conventional cryptosystems such as DES by building a new system which has longer keys and which uses the original system as a building block. We propose a new variant of two-key triple encryption which is not vulnerable to the meet in the middle attack by van Oorschot and Wiener. Under an appropriate assumption on the security of DES, we can prove that our system is at least as hard to break as single DES.
