Paper 2018/1095

Scalable One-Time Pad --- From Information Theoretic Security to Information Conservational Security

Wen-Ran Zhang

Abstract

Whereas it is widely deemed an impossible task to scale down One-Time Pad (OTP) key length without sacrificing information theoretic security or network traffic, this project started with the attempt to develop a paradigm of Scalable One-Time Pad (S-OTP) ciphers based on information conservational computing/cryptography (ICC). This line of research, however, hits a dead-end at the limitation of computational precision for full information conservation when long messages are transmitted. The deadend suggests a 2-phase study. First, to explore the boundaries of scalability with data compression to reduce a long message to a tiny minimum but assuming only partial information conservation. Second, to explore the possibility of scalability with full information conservation but with limited increase of network traffic for transmitting long messages with information theoretic security. This paper reports results of the first phase. It is proven that OTP key length can only be scaled down for partial information conservation on IEEE binary64, 128, and 256. Significant traffic and key reduction is possible but only at the expense of information loss. It is suggested that minimal partial information of a long message may only show the document size and layout. This study suggests two future directions of ICC: (1) scale down OTP key length at the expense of limited increase of network traffic for full information conservation; (2) develop a type of quantum crypto machine for full information conservation. Some mysteries and challenges are discussed.