论文标题
用更快的键扩展范围安全加密
Entropically secure encryption with faster key expansion
论文作者
论文摘要
熵安全的加密是一种用小键加密大型明文，并且仍然具有信息理论安全性，因此，在某种意义上，Shannon的结果表明了完美的加密要求至少要比宣传镜的熵至少要具有钥匙。熵安全的加密不是完美的，并且仅当在明文的熵上已知下限时才起作用。典型的实现是将短键扩展到明文的大小，例如通过使用公共随机字符串乘法，然后使用一次性PAD加密。这在经典和量子设置中起作用。在本文中，我们引入了一种比现有的新密钥扩展方法更快。我们证明它具有相同的安全性。当关键长度是消息长度的相当一部分时，速度增益最为明显。特别是，在量子状态的近似随机化的情况下，获得了2个因子。
Entropically secure encryption is a way to encrypt a large plaintext with a small key and still have information-theoretic security, thus in a certain sense circumventing Shannon's result that perfect encryption requires the key to be at least as long as the entropy of the plaintext. Entropically secure encryption is not perfect, and it works only if a lower bound is known on the entropy of the plaintext. The typical implementation is to expand the short key to the size of the plaintext, e.g. by multiplication with a public random string, and then use one-time pad encryption. This works in the classical as well as the quantum setting. In this paper, we introduce a new key expansion method that is faster than existing ones. We prove that it achieves the same security. The speed gain is most notable when the key length is a sizeable fraction of the message length. In particular, a factor of 2 is gained in the case of approximate randomization of quantum states.
