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看来很难给公开密钥密码学的计算保密性下一个正式定义。定义了一种稍有不同的概念,称为瞬时密钥密码学,并给出了它抗选取明文攻击的保密性的自然定义。这里所提出的主要结果是:存在一种计算的相对模型,在这种模型下,确实存在保密的瞬时密钥密码体制。实际上,存在一种可计算的oracle(神谕机或外部信息源),密码人员可以用它有效地加、解密消息,而对企图解出不是给他本人的消息的密码分析人员却毫无帮助。作为推论,还存在一种长度不变的置换,在其定义域的大多数元素上都难于求其逆置换,即使函数本身允许免费任意求值。
It seems hard to give the next official definition of cryptographic secrecy for public-key cryptography. Defines a slightly different concept called instantaneous key cryptography and gives its natural definition of the confidentiality of anti-selective plaintext attacks. The main result presented here is that there is a computational relative model in which there is indeed a secret instantaneous key cryptosystem. In fact, there is a computable oracle (clergy machine or external source) that cryptographers can use to efficiently encrypt and decrypt messages, but nothing to the cryptanalyst who attempts to find out what is not for himself help. As a corollary, there is also a constant-length permutation that is difficult to find in most of its domain elements, even if the function itself allows free arbitrary evaluation.