A Modular Approach to Registered ABE for Unbounded Predicates Crypto 2024
Prior constructions and motivations for a modular approach to Registered ABE for unbounded predicates in the field of cryptography. The work addresses limitations in pairing-based Reg-ABEs and presents solutions for large universes, unbounded policy size, multi-use attributes, and more. Comparisons are made among different schemes for security assumptions. Emphasis is placed on achieving non-monotone, adaptive, and composite-order group structures.
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A Modular Approach to Registered ABE for Unbounded Predicates Crypto 2024 NuttapongAttrapadung1, Junichi Tomida2 1AIST 2NTT Social Informatics Laboratories
Prior Constructions Pairings [HLWW23, ZZGQ23, FFMMRV23 (RIPE), ZLZGQ24 (R-IPFE)] Obfuscation/WE [HLWW23, FWW23, FFMMRV23 (RFE), DPY23 (RFE)] Bounded User Quadratic (structured) CRS Boolean Formulas Black Box/Concrete Efficiency Unbounded User Unstructured CRS Circuits Non-black box Our work 2
Motivation ("Biology" AND "Ph.D.") OR ("Art History" AND ("Ph.D." OR "Master")) "Biology , Master Multi-use Attribute size Policy size "Biology , "Art History , Ph.D. , Master ? Attribute universe In previous pairing-based Reg-ABEs, we have the following limitations: Small universe Bounded policy size Bounded multi-use Bounded attribute size We solved these limitations! 3
Our Work ("Biology" AND "Ph.D.") OR ("Art History" AND ("Ph.D." OR "Master")) "Biology , Master NOT Multi-use Attribute size Policy size "Biology , "Art History , Ph.D. , Master ? Attribute universe = 0,1 We present pairing-based Reg-ABE with Large universe Unbounded policy size Unbounded multi-use Unbounded attribute size Non-monotone 4
Comparison among Reg-ABE Large universe Unbounded policy size Unbounded multi-use Unbounded attribute size Non- Scheme Security Assumption monotone HLWW23 N/A Adaptive SD ZZGQ23 N/A Adaptive DDH Ours Adaptive MDDH Composite-order groups 5
Comparison among Black-Box Reg-ABE Large universe Unbounded policy size Unbounded multi-use Unbounded attribute size Non- Scheme Security Assumption monotone HLWW23 N/A Adaptive SD ZZGQ23 N/A Adaptive DDH Ours Adaptive MDDH BDHE variant SD, Prog-free ind GLWW24-1* Static GLWW24-2* N/A Adaptive Composite-order groups *Concurrent work, small CRS 6
Comparison among Black-Box Reg-ABE Large universe Unbounded policy size Unbounded multi-use Unbounded attribute size Non- Scheme Security Assumption monotone HLWW23 N/A Adaptive SD ZZGQ23 N/A Adaptive DDH Ours Adaptive MDDH BDHE variant SD, Prog-free ind GLWW24-1* Static GLWW24-2* N/A Adaptive Composite-order groups Unbounded predicates *Concurrent work, small CRS 7
High Level Strategy A modular approach to vanilla ABE with unbounded predicates by [Attrapadung19, AT20]. We adapted it to registered ABE. 9
Modular Approach by [Attrapadung19, AT20] IBE* ABE for an unbounded predicate* A series of ABE transformations* Proving each transformation preserves security is sufficient. This is easier than directly analyzing ABE. *Precisely, they considered corresponding PESs and PES transformations. 10
Our Approach Reg-IBE* Reg-ABE for an unbounded predicate* A series of Reg-ABE transformations* We need that each transformation preserves well-formedness as well as security. We devised a new series of transformations. *Precisely, we considered corresponding PESs and PES transformations. 11
Well-formedness in Reg-ABE Is it trivial? curator mpk aggregate Well-formedness Every attribute meets a certain pk sk attribute form so that they can be aggregated correctly. 12
Summary We presented Reg-ABE for unbounded predicates. - Large universe, unbounded policy size, multi-use, attribute size, etc. We adapted the modular framework in vanilla ABE by [Attrapadung19, AT20] to Reg-ABE. The main difference from [Attrapadung19, AT20] is that we need to handle well-formedness in reg-ABE. 13
