Remarks on the Cryptographic Primitive of Attribute-based Encryption

TL;DR

This paper discusses the fundamental limitations of attribute-based encryption (ABE), highlighting the difficulty in truly excluding unintended recipients due to key exchange among users, which challenges its cryptographic assumptions.

Contribution

It provides a critical analysis of ABE's core primitive, emphasizing inherent practical limitations in achieving perfect recipient exclusion.

Findings

ABE cannot reliably exclude unintended recipients due to key exchange

The flaw questions the security assumptions underlying ABE systems

Highlights the need for revisiting ABE's cryptographic foundations

Abstract

Attribute-based encryption (ABE) which allows users to encrypt and decrypt messages based on user attributes is a type of one-to-many encryption. Unlike the conventional one-to-one encryption which has no intention to exclude any partners of the intended receiver from obtaining the plaintext, an ABE system tries to exclude some unintended recipients from obtaining the plaintext whether they are partners of some intended recipients. We remark that this requirement for ABE is very hard to meet. An ABE system cannot truly exclude some unintended recipients from decryption because some users can exchange their decryption keys in order to maximize their own interests. The flaw discounts the importance of the cryptographic primitive.