We consider the problem of constructing an unconditionally secure cipher for the case when the key length is less than the length of the encrypted message. (Unconditional security means that a computationally unbounded adversary cannot obtain information about the encrypted message without the key.) In this article, we propose data compression and randomization techniques combined with entropically-secure encryption. The resulting cipher can be used for encryption in such a way that the key length does not depend on the entropy or the length of the encrypted message; instead, it is determined by the required security level.

翻译：我们考虑了当关键长度低于加密电文长度时,为案件构建一个无条件安全的密码的问题。 (无条件安全意味着一个没有计算约束的对手不能在没有钥匙的情况下获得加密电文的信息。 ) 在本篇文章中,我们提出了数据压缩和随机化技术,同时使用非自然安全加密。 由此产生的密码可用于加密,使关键长度不取决于加密电文的长度或加密电文的长度;相反,它由所需的安全级别决定。