No reduction from Selective Security to CP-ABE: IND-CPA Security
A reduction of class unstated from Selective Security to CP-ABE: IND-CPA Security would imply a contradiction.
Statement
Migrated verbatim from attribute-based-encryption:
KP-ABE and CP-ABE are syntactically dual: swapping the roles of and converts one definition into the other. This structural observation is useful for intuition but does not give a black-box security reduction. In particular, a selective KP-ABE security proof does not imply adaptive CP-ABE security via the syntactic swap, because the two games have different admissibility constraints and different distributions of challenge objects.
Notes
source: folklore: the claim carried no citation on the page it was
migrated from, and none was invented.
Recorded during migration and not fixed — these are claims about the source text, not changes to it:
- NO CITATION. States a negative result (‘does NOT give a black-box security reduction’) with a reason but no source. This is the classic ‘no black-box reduction’ claim shape and needs either a citation or a folklore marker.
- The justification given (‘the two games have different admissibility constraints and different distributions of challenge objects’) is an argument sketch, not a proof, and is presented as settled.
- Related claim at line 108 (‘the conversion for CP-ABE can incur exponential loss in the formula size’) is a second uncited barrier-flavoured statement on the same page.