On the Information-theoretic Security of Combinatorial All-or-nothing Transforms

• Main Authors: Akao, S. (Author), Esfahani, N.N (Author), Gu, Y. (Author), Miao, Y. (Author), Sakurai, K. (Author)
• Format: Article
• Language: English
• Published: Institute of Electrical and Electronics Engineers Inc. 2022
• Subjects: All or nothings; Brute-force attack; Cryptography; Electronic mail; Information security; Information- theoretic securities; Information theory; Perfect securities; Pre-processing techniques; Probability distribution; Probability distributions; Probability: distributions; Random variables; Security; Security of data; Security properties; Transforms; Unconditionally secure; Upper bound; Upper Bound
• Online Access: View Fulltext in Publisher

 All-or-nothing transforms (AONTs) were proposed by Rivest as a message preprocessing technique for encrypting data to protect against brute-force attacks, and have numerous applications in cryptography and information security. Later the unconditionally secure AONTs and their combinatorial characterization were introduced by Stinson. Informally, a combinatorial AONT is an array with the unbiased requirements and its security properties in general depend on the prior probability distribution on the inputs s-tuples. Recently, it was shown by Esfahani and Stinson that a combinatorial AONT has perfect security provided that all the inputs s-tuples are equiprobable, and has weak security provided that all the inputs s-tuples are with non-zero probability. This paper aims to explore on the gap between perfect security and weak security for combinatorial (t, s, v)-AONTs. Concretely, we consider the typical scenario that all the s inputs take values independently (but not necessarily identically) and quantify the amount of information H(X|Y) about any t inputs X that is not revealed by any s – t outputs Y. In particular, we establish the general lower and upper bounds on H(X|Y) for combinatorial AONTs using information-theoretic techniques, and also show that the derived bounds can be attained in certain cases. Furthermore, the discussions are extended for the security properties of combinatorial asymmetric AONTs. IEEE